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from e31faq.com

As part of the CARB/OBD regulations the engine control module must determine if misfire is occurring and also identify the specific cylinder(s) and the severity of the misfire event, and whether it is emissions relevant or catalyst damaging. In order to accomplish these tasks the control module monitors the crankshaft for acceleration losses during firing segments of each cylinder based on firing order.

The process of misfire detection continues well after the diagnostic drive cycle requirements have been completed. Misfire detection is an on-going monitoring process that is only discontinued under certain conditions.

Misfire detection is only disabled under the following conditions:

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Misfire Detection Example: M52 (6 Cyl.) with Siemens System

The misfire/engine roughness calculation is derived from the differences in the period duration (T) of individual increment gear segments. Each segment period consist of an angular range of 120° crank angle that starts 78° before Top Dead Center (TDC).

Increment gear wheel segment period measurement:

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• If the combustion process in all cylinders is functioning correctly, the period duration of each segment will be identical (i.e. T0 = T1 = T2 = T3 = T4 = T5).

• If a misfire is encountered in a cylinder, the period duration (T) of that cylinder will be extended by a fraction of a millisecond (i.e. T3 > T0, T1, T2, T4, T5).

• All measured values of T are evaluated within the DME, corrected based on sensor adaptation and compared to a set of predetermined values that are dependent on engine speed, load and engine temperature.

If the expected period duration is greater than the permissible value a misfire fault for the particular cylinder is stored in the fault memory of the DME. Depending on the level of misfire rate measured the control unit will illuminate the “Check Engine” light, may cut-off fuel to the particular cylinder and may switch lambda operation to open-loop. All misfire faults are weighted to determine if the misfire is emissions relevant or catalyst damaging.

Emissions Relevant:

During an interval of 1000 crankshaft revolutions the misfire events of all cylinders are added and if the sum is greater than a predetermined value a fault will be set identifying the particular cylinder(s). The Check Engine light will be illuminated during after the second cycle if the fault is again present.

Catalyst Damaging:

During an interval of 200 crankshaft revolutions the misfire events of all cylinders are added and if the sum is greater than a predetermined value a
fault will be set identifying the particular cylinder(s). The “Check Engine” lamp:

• On vehicles with a Siemens Control Module (M52 engines) - the lamp will immediately go to a steady illumination since fuel to the injector(s) is removed. Fuel cut-off to the cylinder will resume after several (≈ 7) periods of decel if crankshaft sensor adaptation is successfully completed or the engine is shut-off and restarted.

• On vehicles with a Bosch Control Module (M44, M62 & M73 engines) - the lamp will blink as long as the vehicle is operated within the specific criteria under which the fault occurred. Fuel to the misfiring cylinder is not cut-off as long as the “Check Engine” light is blinking. In each case the number of misfire events permitted is dependent on engine speed, load and temperature map.

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Crankshaft Sensor/Flywheel Adaptation:

In order to eliminate misfire faults that can occur as a result of varying flywheel tolerances (manufacturing process) an internal adaptation of the flywheel is made. The adaptation is made during periods of decel fuel cut-off in order to avoid any rotational irregularities which the engine can cause during combustion. (i.e. Crankshaft sensor adaptation displayed on M73 with DIS 12.0)

In order to establish crankshaft sensor adaptation 7 periods of decel fuel cut-off are required. This adaptation is used to correct segment duration periods (time from TDC1 to TDC2, to TDC3, etc.) prior to evaluating for a misfire event.

If the sensor wheel adaptation has not been completed the misfire thresholds are limited to engine speed dependent values only and misfire detection is less sensitive. The crankshaft sensor adaptation is stored internally and is not displayed via DIS or MODIC. If the adaptation limit is exceeded a fault will be set (M52 only).

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ENGINE MISFIRE DIAGNOSIS

(OBD II monitoring criteria considered)

Engine Misfire is the result of inefficient combustion in one or more cylinders. The causes of Engine Misfire are extensive but can be grouped into the following sub-systems. Consider the charts below as an additional diagnostic aid once the DIS is connected, the correct fault symptom has been chosen and the fault memory has been interrogated. Follow the Test Module as displayed by the DIS.

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from e31faq

Project Overview

Vehicle Information: US Spec 2000 (05/99 build) 750iL (M73 V12)

This was my second teardown of the intake to correct leaking valve cover gaskets.

Tools Used/needed (Not an exhaustive list)

• 10mm Socket • 8mm Socket

• 8mm Hexhead or starhead

• 10mm open ended wrench

• A least three 6 inch 3/8” extensions

• Flexible 3/8” extension

• Flexible 3/8” joint

• Magnetic wand

• A good torque wrench

Other

• Hylomar HPF Sealer

• New spark plugs (Recommended)

• New Crank Case Ventilation valves and boots (Recommended)

• BMW TIS (I do not recommend you undertake this without a copy of the TIS)

• Lots of latex gloves Notes Don’t force anything. Things that break will be expensive.

Credits

• http://bmwe32.student.utwente.…V12_QuickRoughIdleFix.htm

• http://bimmerboard.com/forums/e38/

Disclaimer

This document is based on my experience only and does not constitute a guide or how to on performing a valve cover replacement. You assume any and all liability for any work performed on your vehicle. If you don’t know what you are doing, you probably shouldn’t be doing it.

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Figure 1– starting point

Top side preparation

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Figure 2

• Remove front and rear brackets The front bracket requires the bolts to be removed (10mm) The rear bracket only needs the bolts loosened (8mm)

• Loosen all of the support bolts for the injector sound barrier Move each barrier by sliding it towards the vendors

• Remove the two throttle body electrical connectors These “turn” counter clock-wise to loosen and remove

• Remove BATT+ connector box This lifts straight-up and off the metal support bracket. Careful: The plastic is brittle and breaks easily. See:Detail Image 2– BATT+ connector removal

• Now is a good time to remove air intake hoses and air-cleaner boxes

Removal: Drivers side wiring Loom

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Figure 3

• Remove the marked connectors above Five connectors in total to free to drivers side wiring loom See: Detail Image 1 – Connector removal

• The ignition coil may have a wire tie holding the slide in place. Cut the wire tie to remove connector

• The connector on the alternator is much easier to access once the airbox housing is removed.

WARNING: Mark or otherwise note which connector goes where. Several of these connectors are identical and interchangeable at the plug level. That does not mean the BMW computer thinks they are interchangeable. Getting them back in the right place is critical to your car running correctly!

Removal: Passenger side wiring loom

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Figure 4

• Remove the connector just below the intake rail next to the oil dipstick

• Remove the diagnostic plug This unclips via the small plastic tab on the backside of the plug

• Remove the plug to the coil Located under the diagnostic plus

• The wiring harness has two connectors under the car.

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Figure 5 – Oil pan view from passenger side front

• The last two connections on the passengers side are located under the car This requires removal of the plastic airflow pan See: Detail Image 3

• These connectors free up the passenger side wiring harness

Wiring box additional connections

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Figure 6

• Remove the oil fill cover and oil drip plate by prying it away from the front of the engine See: Detail Image 4 – Oil drip catch

• Unclip the two connectors located under the oil entry spout

• The first connector (show above under the coolant hose) is a standard clip. To undo, see: Detail Image 1 – Connector removal

• The connector under the oil spout is more difficult. The easiest method seems to be a flat blade screwdriver between the receptacle and the plug. Slowly (carefully) twist flat blade to pry the connector off.

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Figure 6

• Disconnect the fuel injector connectors. This works best with a long, narrow flat blade screw driver. Push the holding ping gently toward the connector and gently pull up. See: Detail Image 1 – Connector removal

• Disconnect knock sensor plugs. A small flat blade screwdriver can be used to (carefully) pry the connectors apart.

• Remove the holding nut located near the firewall on the passenger side. This requires a flexible extension.

• Remove other connectors as necessary. These may be in various locations depending on your build date.

• Pull the vacuum lines away from the wiring box

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Figure 7

• Loosen/unbolt the vacuum value (2) and holder. This is bolted (2 bolts) to the auto-level/power steering reservoir NOTE: This is required to free the two vacuum lines (shown in Figure 7). These two vacuum lines are connected to the underside of each intake manifold. Disconnecting them from the valves will make it much easier to remove the manifolds.

• The wiring box is now free. Push (carefully) back toward firewall and lift the front upwards. Secure to hood.

Fuel Rail Removal

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Figure 8

• Loosen and disconnect the inbound/outbound fuel lines (two) by loosing the fuel rail clips.

• Remove the hex bolts (4) from the fuel rails.

• Carefully pry the two fuel rails out. The rails can be removed together.

NOTE: Once the hex bolts are removed, the rails are held in place by the rubber O-rings sealing the injectors to the intake manifold carefully pry at various points on the two rails. It takes a little upward force to get the injector seals to break loose.

OPTIONAL

You may choose to remove the throttle body assembly at this point. This may make it easier to handle the vacuum lines attached underneath each. I didn’t remove them during this teardown.

Intake Removal

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Figure 9

• Remove the two nuts. These hold the ignition wiring harness and vacuum line routing clips to the intake. Pull the tabs off the bolts once the nuts are removed

• Remote the two vacuum connections

NOTE: The rear vacuum connection may be easier to remove once the intake is loosened and partially removed.

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Figure 10

• Remove the upper and lower nuts (10mm) Upper nuts are fairly easy to reach Lower nuts require at least 14” of ¼” extension and a flexible attachment NOTE: There is no easy way to remove the lower nuts. This process takes time and patience. Use a magnetic wand and/or magnetic socket to prevent nut loss when removing

• Carefully remove the intake by pulling out and up. This takes some care and patience as there is a vacuum hose connected to the underside and there is very little room to work in.

NOTE: Be aware the crankcase ventilation valve is mounted on the rear of the intake and is also connected to the valve cover. The seal should break when the intake is lifted up and out. See: Detail Image 5 – Removed intake manifold See: Detail Image 6 – Engine without intake manifolds

• Repeat process for other side of engine.

Valve Cover Removal

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Figure 11

• Remove valve cover nuts to remove valve covers.

The Oil Leak

Once under the intake manifold, I discovered the leak was not the valve cover gaskets (a darn good thing as I had replaced them about 6 months prior to this project due to an oil leak). The oil leak was from the driver’s side Crank Case Ventilation valve boot. This boot marries up the valve covers to the actual CCV valve. I must have damaged it during my last teardown exercise.

See: Detail Image 7 – The cause of the oil leak

Putting it all back together

This is pretty much “reverse the steps above”.

Again, the hardest part is putting the nuts back on for the intake manifold. A magnetic wand to start the nut seems to be the easiest method. This simply takes time and patience.

Coat all seals with Hylomar HPF sealer

Torque settings used for my vehicle

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Detail Images

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Detail Image 1 – Connector removal

• Push the metal clip towards the plug.

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Detail Image 2– BATT+ connector removal

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Detail Image 3 – Engine pan

• Each screw requires about one turn to loosen.

NOTE: screws do not need to be removed from the plastic pan.

Push the pan toward back of car to unclip and remove.

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Detail Image 4 – Oil drip catch

• The oil catch unclips (with a little help) Use a flathead screwdriver to carefully pry the catch pan out.

NOTE: do not hit the fan blade when removing. Damage to the fan blade could result in the infamous “exploding fan” problem.

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Detail Image 5 – Removed intake manifold

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Detail Image 6 – Engine without intake manifolds

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Detail Image 7 – The cause of the oil leak

from e31faq.com

Every time somebody complains about rough running, everybody else chimes in "clean your DKs."

Why?

My DK motors have not been touched since new. They work fine, only thrown an EML light once with some pretty ancient batteries.

A bad DK will manifest itself either with

1. An EML light and possibly a bank shutdown, and

2.) A VERY characteristic and slight grinding sensation during idle indicating the banks are not mass airflow balanced and thus in need of synching. That's it. Given a few minutes with a warmed up engine, EML will balance the banks automatically during an extended idle - no need for a coast-down.

EML performs a series of power-up and continuous checks against the pedal position sensor and DKs to ensure they're within mechanical limits. Given the age of the design, it's pretty sophisticated and mandated by both the FMVSS and TUV for fail-safe operation. If there were mechanical lash or feedback issues, the comparator function within EML would find it way before you could.

There's a reason Bosch doesn't offer a field reconditioning kit for their DKs. Even though it's a mechanically simple design (for safety's sake), there's a lot to go wrong during reassembly, including destroying the feedback wiper and disc.

I'd rather see folks direct their attention to the more problematic fuel pumps, coils, and plugs. A good fuel pressure check is relative easy, cheap, and informative.

So, check everything else FIRST, and do the DKs LAST. And only if they're throwing an EML light, repeatedly.

Mark in SBA

from http://www.e31faq.com

Installation instruction

Chip in BMW Motronic
For model E31 / E32 with M70 Motor (12 Cyl.)

PLEASE READ THIS INSTRUCTION TO THE VERY END BEFORE STARTING THE JOB !

This is an installation instruction describing the exchange of the original chip with a reprogrammed high performance chip.

The pictures are partially taken from a BMW E34 / 540i, but can also be referred to for other BMW model’s ECUs.

Necessary tools

Size 2 Philips head screwdriver, thin pliers or 3/8“ ratchet with 10mm nut (see text), screwdriver about 5mm wide, screwdriver about 3mm and eventually a torx screwdriver (see text), normal pliers.

Location of the ECU

In the E31 the ECUs (the M70 engine has two ECUs, one per cylinder bank) are located under a large black plastic cap right in front of the bulkhead. This plastic cap is secured with 4 large Philips head screws.

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What are the functions of the various ECUs?

Under the plastic cap you find three units at the 850i/Ci.

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850i/ci from left :

EML - DME1 – DME2. DME (Digital Motor Electronic) is a more specific expression for ECU (Electronic Control unit). The transmission ECU is located somewhere else.

EML is the electronic throttle control unit.

How to take out the DME and where to find the Motronic (DME) number?

All ECUs are either secured with M6 nuts (earlier models) or secured with special clamps (later models).
Prior to unmounting the units detach the big black connectors and carefully bend them aside.

On the DME one can find several stickers. Only the large one is of any relevance carrying the number 0 261 200

xxx XXX stands for either 156 or 352.

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Opening the DME

After having taken out the DME the unit needs to be taken apart in order to change the socketed chip.
First of all the cover carrying the number sticker needs to be taken off. On later units the aluminium cover is secured with additional torx screws which need to be taken out first.

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Afterwards loosen the clamps on the back side of the unit. This is easiest with the 5mm wide screwdriver. It’s a total of 6 clamps which like to break off on the aluminium covers which isn’t a big dilemma though. The torx screws are strong enough to hold the cover.

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Now the cover can be taken off and the one of the main differences between the 156 and the 352 ECUs becomes obvious:
The 156 ECU has two PCBs (printed circuit board) while the later 352 has only one.
The next steps describe how to take apart a 156 ECU. If you have a 352 unit you can jump to the section describing the removal of the chip.

Detaching the two PCBs from eachother (DME 156)

The chip is located on the upper PCS hidden under an either black or white plastic cap. In order to get access to the chip you need to detach the two PCBs from each other which is a bit tricky. For this exercise you need both screwdrivers (3mm and 5mm) as well as the torx driver.

The PCBs are attached to each other at five points:
Via a torx screw, two plastic connectors in the back of the unit and in the front where the electric connections are. This is the tricky part because here the connection is over the full width of the unit plus additional clamping on each side. The fifth point is in the middle of the unit (white spot in the above picture).

First step is to unscrew the torx screw securing the PCB to the unit’s case. Next open the little white plastic connector in the middle of the PCB (see picture) connecting the two PCBs.

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After this open the rear two plastic connectors by pulling them apart:

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Now on the front side open the left and right plastic clamp:

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Just bend them open with the 5mm screwdriver. Normally they stay in this position afterwards:

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Now the horizontal clamping needs to be opened, which is tricky but possible…

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…if you push the upper PCB backwards at the same time. Once you have achieved this it looks like on the below picture:

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Now you can flip it open which looks like below:

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After removing the plastic cap (the white one in the above picture, can be black as well) it looks like below:

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Carefully remove the chip from the socket by using the 3mm screwdriver. Please note that the chip has a little marking (slot) on one of the short sides pointing to where the finger is on the above picture. When installing the new chip make 100% sure the mark shows
in the same direction.

MOUNTING THE CHIP THE WRONG WAY AROUND CAN KILL IT !!!

IMPORTANT INFO REGARDING THE M70 ENGINE:

The M70 is controlled via two DME.

The DME 0 261 200 156 has two PCBs with identical chips. These chips are interchangeable.

The DME 0 261 200 352 has only one PCB and the two DMEs have DIFFERENT chips despite identical stickers on the original chips!!!

Therefore the performance chips are also NOT IDENTICAL and must not be exchanged with each other.

The performance chips are marked accordingly. If you exchange them by accident the engine won’t even start. Also make sure NOT TO EXCHANGE the DMEs. If it should happen accidentally you won’t damage the engine, but you’ll recognize a serious loss of performance.

The Top speed limitation (Vmax) is NOT programmed into the DME chips but in the EML chip. In order to get rid of this limitation the EML chip needs to be replaced as well. The mechanical construction of the EML ECU is similar to the 156 DME. The necessary steps to open the EML ECU are according to the ones described before for the 156 DME.

from e31faq.com

I've just got around to changing the fluid, filter and flushing the trans on my 1991 850i. It's been about 60,000 Km since it was done previously but the results as far as improvement in shift-smoothness have made it very worthwhile and made me think I should post the process for other's enjoyment.

It is quite a simple job for someone who has reasonable mechanical aptitude and a reasonable selection of tools. Takes 2-3 hours. Most important is a clean place to do the job, auto transmissions have little tolerance for dirt and, as changing the filter means removing the oil pan, you don't want any dirt to be blowing around while it's opened up. Also make sure you have lots of rags around to wipe your hands continuously, it's VERY important to keep any dirt, dust or grit out of the trans.

Before you start, you will need a new pan gasket and a filter and O ring set, these are all available after-market for around US$20ish. Plus you'll need about 10 liters of Dexron 3 ATF. It's also worthwhile to give the underside of your car in the trans area a high pressure wash, as it will make the job a lot cleaner, especially if it's greasy under there.

1. Take the car for a run so the trans fluid is warm and well stirred up, you want any contaminants to be well mixed in the fluid, so they drain out readily.

2. Raise the front of the car up on stands or ramps (apply common sense safety precautions when working under your car), so you can crawl under and get to the trans area. Make sure your work area is clean and there is no dirt or dust likely to be blowing around.

3. Loosen (because it will be on real tight) the huge bolt holding the dipstick tube to the front of the oil pan. Also loosen the trans cooler return pipe where it connects to the bottom of the trans, just forward of the oil pan (19mm spanner) The reason for doing these 2 steps now is that they are the most likely to trip you up. If you cannot budge either of these then you're best to enlist help.

4. Remove the drain plug from the centre of the transmission pan, there will be 4-5 liters of fluid that will come out, so be prepared, it may also be scalding hot. Once it's drained completely, reinstall the drain plug.

5. Remove the huge nut and then dipstick tube from the front of the oil pan. No need to remove the upper dipstick tube mounting, as there's enough movement to swing the tube away from the pan with this in place. There will be a little fluid that comes out when you do this, so have your drainage container underneath.

6. Place a good thick mat of newspaper on the floor under the oil pan. This will catch and contain any drips and spills that will occur in subsequent steps.

6. Loosen the 6 x 10mm bolts holding the oil pan to the trans body by turn at a time, so as not to put uneven stress on the pan. To make this job less messy, I recommend loosening them all a few more turns then giving the pan a good whack with your hand to un-stick the gasket and pan from the body of the trans. This will allow a "controlled descent" of the pan, which will still contain some residual fluid. When the pan is loose from the trans body, next remove the 4 bolts holding it in the corners. Finally remove the final 2 bolts along each side, while holding the pan up with your other hand. Lower the pan, keeping it level but with rear end slightly lower, so the residual fluid doesn't come out the hole where the dipstick attaches.

7. Place your drainage container under the trans to catch the continual drips that will be falling. Resist the urge to wipe the internals of the transmission to clear these away. The reason for this is 2 fold - firstly any lint or fluff on your shop rag will end up inside the trans (not good) and 2ndly it will continue to drip no matter how much you wipe!

8. Remove the filter from the bottom of the trans. This is held in place by 3 x Size 27 Torx head screws. When it comes away, there will be a fair bit of fluid inside it, so be ready with your drainage container. There is also an O ring which seals the filter outlet with the valve body in the trans. Make sure it comes away with the filter, else remove it from the valve body. Your new filter kit will come with a replacement O ring. You will notice that the old filter is covered in a very fine black film, this is normal and does not mean your trans is on it's way out.

9. Remove the plastic wrapping and the plastic protector ring from the new filter. Install the new O ring on the new filter, the lip on the filter, around which the O ring locates is sharp, so take care not to damage the O ring or your fingers.

10. Locate the new filter complete with O ring on the bottom of the trans, ensuring it is correctly seated and the O ring is in place and not pinched. Secure it with the 3 x Torx head screws and tighten them snugly. Always be careful not to over tighten screws and bolts.

11. Now have a look in the oil pan. When you drain the remaining fluid from it, check if there's any sediment in the bottom. Apart from the thin black film, it should be fairly clean. If there are metal bits, lumps or sludge in significant quantity you could be in trouble. Note there are 2 magnets in the pan to collect metals from the fluid. It's normal to find these covered in a black sludge, which will feel smooth like grease. If it's gritty or there are bits of metal in there, again you could be in trouble. Thoroughly clean the pan internally and externally and clean the magnets. Make sure everything is spotless. Ensure the magnets are put back in their circles inside the pan. Check the sealing edge of the pan to ensure it's free of any damages. If you have had fluid leaks from the oil pan previously, check that the pan is not bent or warped. Best way to do this is to place the pan on a sheet of glass (even if it's still in a window!) It should sit flat with no significant gaps anywhere around the edge.

12. Back under the car, clean the lower face of the trans against where the oil pan seals using some lint free rag and solvent (petrol works well) Ensure this face is spotless and free of any damage, this will allow the pan to seal leak free.

13. Install the new pan gasket on the pan. Do NOT use any gasket sealant! The gasket doesn't stay put very well, so take care not to dislodge it when you reinstall the pan on the bottom of the trans. As before, hold the pan in place with one hand while you reinstall the 2 bolts and pan retaining fittings in the middle of each side of the oil pan. Leave these loose at this stage while installing the final 4 bolts in the corners. Once all 6 bolts are loosely installed, carefully check that the gasket is correctly positioned around the entire circumference of the pan. If it doesn't look right, remove the pan and reinstall the gasket correctly. Once you are happy that the gasket and pan are correctly installed, progressively tighten, in a zigzag pattern, the 6 securing bolts. Finally, only tighten these enough to bring the pan retaining blocks into contact with the trans body. These are designed to put exactly the right amount of pressure on the pan and gasket to ensure it seals - do NOT over tighten.

14. Reinstall the dipstick tube on the front of the oil pan. Wipe the outside of the pan so it's clean and dry, this will make checking for leaks easier when you refill it in the next step.

15. Refill the trans through the dipstick tube; note this will need a long funnel or a funnel with a piece of tubing on the end of it. Fill it slowly (this bit can be tedious) as the dipstick tube takes the fluid very slowly and has a tendency to overflow at the slightest provocation. What I did was to get a piece of plastic tubing that fitted tightly inside the dipstick tube and also fitted tightly around the outside of my funnel, therefore there was no chance of overflowing around the dipstick tube. Ensure the funnel and tubing is spotlessly clean before using them. At this stage you need to put 5 liters of fluid in the trans. While and after filling, check for any leaks around the pan and dipstick attachment to the pan. If there is any seepage at all, fix it before proceeding. This may mean draining out your new fluid and removing the pan again.

16. Now we're going to prepare for the flushing of the torque converter. A bit of transmission theory here... when you drain the oil pan as you have just done, you only remove about 4 of the total of 8.1 liters of fluid from the transmission. The remaining 4 liters is in the torque converter. Every time the transmission shifts gears, a very small amount of friction material wears off the clutches. This friction material stays in suspension in the fluid. The fluid is pumped around the trans, through the torque converter and then through the trans cooler in the radiator before being returned back to the oil pan. Flushing the converter ensures that as much of the old fluid, contaminated with friction material, is replaced with new clean fluid.

17. Assuming your oil pan is leak free; loosen the securing bolt that holds the trans oil cooler pipes along the side of the engine. This bolt is right below the starter motor. This will allow some freedom to remove the cooler return pipe.

18. Next, remove the cooler return pipe from the bottom of the trans, just in front of the oil pan (19mm spanner). Have your drainage container there, as fluid will leak out. Note, there is an O ring on this pipe where it fits into the transmission housing. Be careful with this O-ring, because you're going to re use it - unless you have another handy (12mm O ring).

19. Fluid will be dribbling out of this tube continuously and you need to attach a length of drain tube to it, so you can direct the outlet of this tube into a container. I used a piece of garden hose, as it seemed to fit perfectly and secured it with a hose clamp. You will also need to plug the transmission body from where this pipe was removed. I used a synthetic cork from a wine bottle, which I was able to screw into the threads in the pipefitting. If you don't plug this hole, your new fluid will come out in step 23, as I found out the hard way!

20. Now you need to measure the quantity of fluid that you have drained out of the transmission in total thus far. This will help guide how much is left in the torque converter and needs to be flushed out. I had drained about 4.5 liters from mine by this time. Meaning there was 3-4 liters (trans and converter hold 8.1 liters in total) remaining to be flushed.

21. Place your drain tube into a suitable container that will allow you to measure how much you flush out - I used an old 5-liter oil container, with graduations on the side. 21. Add some more fluid to the trans via the dipstick tube, you will need at least 6 liters in the trans when you start the flushing process, yes it will be overfilled but don't worry at this stage.

22. Make sure you have a drain pan under the trans, in case any of your plumbing springs a leak. You also need to have an assistant at this time to help you.

23. Now start the engine and run at idle in Park. When you do this the transmission will pump the remaining old fluid out of the torque converter and into the container you allocated at step 21. It pumps it out by replacing it with the new fluid you have just put in the oil pan. Watch the container and switch the engine off once it contains the quantity determined in step 20. In my case I drained a further 4 liters. You could get keen and flush a bit more through but you need to be mindful that you only have around 6 liters in the trans to work with, so you may need to add more new fluid during the process, or do it in stages (not ideal in stages as the old and new are more likely to mix in the converter). Also keep an eye on your plumbing during the flush and switch off the engine if you get any significant leaks in your drain hose or plug you have installed in the bottom of the trans body.

24. When you have completed your flush, remove your drain hose and reinstall the cooler return line to the transmission body, don't forget to have the O ring on the end of this tube before you install it. Ensure this tube is correctly located in the transmission body before you start screwing in the 19mm securing nut. It should be possible to do this nut all the way up with only fingers, if you have correctly seated and aligned this pipe in the transmission housing, before finally tightening with a spanner in step 25.

25. Reinstall the cooler line clamp below the starter motor before you finally tighten the 19mm nut securing the cooler return line into the body of the transmission.

26. Work out in total how much fluid you have drained from the transmission, this will allow you to work out how much to put back in at this stage. In my example, I had drained a total of 9 liters, so I put back 8 liters at this stage. I did this because this would be sufficient to check the level using the dipstick and add exactly the right amount to fill the trans to the correct level. It’s easier than overfilling and draining out the excess.

27. Run the engine again after reconnecting up the cooler return line and roughly topping up the fluid to check for leaks. Also move the gear selector into each position to confirm the car engages gear correctly (keep the brakes applied hard if the back wheels are on the ground!). Fix any leaks or seepage from the connections before lowering the car to the ground. If the car doesn't engage gear (i.e.: you don't feel the characteristic "bump" when you go into D or R). Make sure you have sufficient fluid in the trans (i.e.: recheck how much you have drained in total vs. how much you have poured back in). Do not rev the engine during this test, or if it fails to engage gear.

28. Lower the car to the ground and check the fluid level as normal. Add more fluid until correct. Test-drive the car - I did and gear changes were now VERY smooth, especially at light throttle openings. After a test drive, re-check the fluid level again. Note, it is almost as bad for the trans to be over filled, as it is to not be full enough, so spend some time here and get it spot on.

29. During the next week or so of use, check daily under the car that there is no evidence of leaks from the transmission. It should be dry.

Hopefully this is a useful guide to those keen DIYer's to do this job. Happy to answer any questions or fill in gaps in the above.

Good luck, Richard.
(RAC69 on http://www.clube31.com)

from http://www.e31faq.com

I finally got into my glove box yesterday, so I thought I'd share a bit. The problem was that both the upper and lower glove box hatches were locked, even though the locking mechanism was unlocked. This had happened after the glove boxes had been locked for the first time in about three years.

I started by "picking" the upper door. Take a very thin flat-blade screwdriver and insert it into the slot between the doors where the catch mechanisms are (approximately in the middle). You can find this spot by running the blade lightly between the doors. Once you've found the spot, put the blade in on a low angle from the right side with the flat of the blade angled slightly up. Poke around in there, you'll find a hard stop against some metal, and then you'll want to pull the blade toward the seat slightly and see if you can go in further. It takes some patience (singing "Popeye the Sailor Man" may or may not be the key, but it worked for me), but eventually you'll slide the blade in and hear a nice click and the upper door will raise.

Do not be tempted to try the same thing on the lower door. The angles are not there, and the mechanism is rotated 90 degrees, making the pick damn near impossible. The upper door is MUCH easier - it took me about 15 minutes, and I had no clue what I was doing.

Once you've got the upper door open, gently remove the rubber gasket material between the doors (it's got a short fabric nap on the facing surface). It may have some double sided tape holding it down, but on my car it was all dried out so the gasket camp up pretty easily. It's a strong piece of rubber, so don't worry too much.

Once the gasket is up you'll see two screws holding the latch mechanism in place. Remove those and you'll see that the mechanism can be moved slightly from side to side. Move the mechanism as far to the left as you can and hold it in place with one hand. Now move the bottom door as far to the right as you can (it's got some play in it) and pull gently down. The striker in the door should now slide around the catch and the door will be open. If it binds, pull the door down in the middle with some force and see if it releases. There's nothing you can break, so try a real tug. Just be sure to stop pulling when the door releases or you'll pull it through it's stops.

If the bottom catch cannot be jimmied as described above, you should be able to pop the mechanism straight back out. Then you can unlock the mechanism manually. After the two screws are out, the only thing holding the mechanism is a small press-fit plastic piece, which would be difficult to break as long as you pull straight out on the mechanism. Be careful when you pull, there are two pieces of plastic that may come free.

If you are able to get the door open without pulling the mechanism, you now get to pull the mechanism anyway. Just pull straight out on it. Watch for loose plastic.

Once the mechanism is out, you will need to remove the upper glove box liner (4 screws) to gain access to the back of the bulkhead, where the lock position switch is located. When you pulled the mechanism, the two pieces of plastic that may have come free are the keeper that goes on the front side of the bulkhead and a cammed disc on a shaft. Go ahead and re-install the keeper on the position switch. There's a tab on the inside ring of the keeper, it should be set at 9 o'clock.

The cammed disc goes back into the mechanism, cam side inward. Just rotate it until it sits in as far as it can.

The mechanism cover is held by two tabs on either side. The cover is also an anchor for one end of a shaft with a spring pushing on it. You can get the cover off with out the spring flying out if you're careful. Once inside you can diagnose to your heart's content. As it turned out, there was nothing wrong with the stuff under the cover on mine. The mechanism worked perfectly every time once it was out of the car.

My problem seemed to be the cammed disc. When the mechanism is locked by the key, the cams are rotated in such a way that the catches are mechanically separated from the release buttons. When the mechanism is then unlocked, the disk is supposed to rotate back so that the buttons now activate the catches. This was not happening on mine. I looked all over for something that was broken, but couldn't find a thing. The parts that were supposed to engage to rotate the disc to the unlocked position look to me like they were designed with too much slop in them. Beats me how this thing ever worked.

I put some light oil on the parts and got it to work about half the time, but it's still not reliable.

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from http://www.e31faq.com

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2 OEM BMW Lemforder arms + 750 bushings pressed

On the BMW E34, E28 and E32, upper control arms, also called thrust arms are attached to the sub frame through bushings and to the steering arms by ball joints. The bushings are well known for failure because they take most of the load in the front end under braking and may cause the car to shimmy if worn. Shaking of the front end is often cause by worn thrust arm bushings.

Please if you love your BMW use Lemforder (OEM) parts only!!!! Else you will change your arms every year...

Failure syndromes:
- The 50-60 Mph shimmy.
- Severely enhanced brake shimmy.
- Clunk noise (cause by defective ball joint).
- Bushings torn or with small cracks.

You might want to change the whole arm instead of just changing the bushing if the ball joints are worn. Bushings must be pressed into the arm.

Procedure

- 22mm wrench, socket and ratchet.

- Pickle fork (can be loaned from Pep Boys free) and hammer or tie-rod puller.

- WD 40. · Ramps to tighten the bushings.

- New self locking nuts.

1. Raise the front of the BMW E34, support with jacks and remove the wheel.

2. Break the two 22mm nut on the ball joint and on the bushing side.
I change the whole arm (I can damage the rubber boot):

3. Use a pickle fork (it works fine) to remove the ball joint. Or use a tie-rod puller.
I keep my thrust arm (I cannot damage the rubber boot):

4. This is a little bit harder, you will need to put the nut back (not all the way) to protect the threads in case of a bad blow. Use a hammer to tap the ball joint carrier while applying upward pressure to the control arm. Sounds tricky but you are not hitting the thrust rod or the ball joint but the metal were the ball joint goes through. Applying in the mean time a lot of upward pressure with a pry bar causing the ball joint to pop out. Or use a tie-rod puller. It can be done with a pickle fork, but it is hard not to damage the boot.

5. Undo the 22mm nut and bolt attaching the thrust arm to the frame. Remove the thrust arm.

6. If the ball joint turns while tightening the nut, use vice grips or pliers to hold the bottom of the ball joint to the steering plate.
Installation is reverse of removal but don't tighten the 22mm nut holding the arm to the frame all the way. You will need to lower the car to the ground to tighten the thrust arm bushing nut under load (127 Nm, 90 ft-lb). If you have ramps it is time to use them.

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E32 750il bushings
Thrust arm bushings should always be changed in pairs. You will need a press or find a shop with a press if you are not changing the whole arm. The BMW 750il and 850i have a stronger heavier bushing designed for the greater weight of the BMW 750 and 850 front end and engine. They give a firmer tighter suspension feel and steering response. I would not change them until you have problems with your existing bushing. If you have a fair number of miles on your car when you do change them you may as well do the arm and the bushing, since half the time the ball joint is worn also.

Note from Dan Pitts

Thanks for the information concerning how to replace thrust arms. One thing that may be helpful in the procedure is jack up the wheel to take some load off of the ball joint before trying to separate the ball joint from the wheel assembly. I had two pickle forks completely wedged under the ball joint with no movement. I reluctantly put the wheels back on (but not the 22mm nut) and backed out of the garage to prepare for a disgraced drive to the mechanic, when the ball joint popped out. I then replaced the left thrust arm and resumed work on the right side after this moment of joy, but this time I placed the jack under the control arm ball joint and took the load off of the thrust arm ball joint. This time, the ball joint came right off using the pickle fork (actually I used two due to the thickness of the boot). Anyway, thanks for the procedure and the tip on replacement parts.

Note from Dan Trevor D:
On Friday I replaced the Sway bar link, Thrust arm and Control arm on my ’89 535iA using the sections from your troubleshooting section on the thrust and control arms as a guide.
One thing that I discovered was that to remove either the Thrust arm and/or Control arm from the suspension mounting plate, the following simplifies the procedure:
Once three bolts from suspension mounting plate are removed
Remove bolts from Control arm and Thrust arm Bushes. Remove nuts from ball joints of Control arm and Thrust arm. Remove sway bar link (17mm) from mounting plate. Remove tie-rod from mounting plate with a tie-rod puller (I bought one from Repco for $30, probably cheaper in the US) Mounting plate with Control arm and Thrust arm can now be easily removed On your workbench you can now gently knock/tap out the ball joint/s from the mounting plate with a pound hammer. Reassemble. I had initially struggled to try and remove the ball joint ends of the Control arm and Thrust arm from the mounting plate while still attached to the underside of the car.
Using the above procedure I estimate the total time to replace Control arm, Thrust arm and sway bar links to be 1-1.5 hours each side.

P.S. I used a trolley jack and 4 x axel stands – 1 under each front jacking point and two under the cross member under the engine.

Part numbers:

All BMW E34s
BMW Thrust arm Left/Right: 31 12 1 141 097/098
BMW 750i bushings: 31 12 1 136 607

from http://www.e31faq.com

Submitted by: Zatman, Roadfly Member

Note: This may not apply to the V12 engine which is a lot more time consuming as it requires taking off a number of additional components to allow enough room for the radiator to come out.

Disclaimer: This is an account of my experience with replacing the radiator on my car – a 1995 840 Ci auto. Use at your own risk and exercise caution when following. Many opportunities exist to get back & eye injuries, poisoned, burnt, scratched, cut and bruised if you are not careful.

Time needed: 2.5 hours (careful & easy pace) – No lift required.

Tools needed:

1. Screw drivers
a. Phillips (+): Small, medium and large will do

b. Flat blade ( – ) ; small
2. Socket 1/4” or 1/8”

3. Short socket extension
4. Socket 8 mm

5. PTFE tape
6. Large tray to catch the coolant (I used aluminum disposable food trays from Target)
7. A bucket to put the waste coolant in temporarily
8. Some clean non-abrasive cloth to cover the headlight covers
9. Household gloves

10. General rags to mop up. Its gets messy no matter what you do.
11. Kitchen roll (absorbent strong paper)
12. Watering can or a water hose

Spares:

1. Radiator
2. Coolant neat (not the premixed version) 2 US gallons (7.6L) (I used Prestone)
3. Distilled water 2 US gallons (7.6L)
4. Expansion tank (Optional – highly recommended if you have the old style two color black/yellow tank – don’t forget 1 extra small size hose clip)

5. Radiator Cap (Optional – highly recommended if your cap doesn’t say 200 on the inside)
6. Plastic bleed screw (Optional – recommended)
7. Hose clips (Optional – 2 large, 1 medium & 1 small)

8. Hoses (Optional on condition – don’t forget the extra clips on the engine side if you decide on replacing the hoses)
9. Temperature sensor (Optional – There are two kinds available each switching at different temperatures. You only need one.)
10. Plastic clips for the air duct shroud (Optional – in case you break some when removing)

Procedure:

1. Work on a cold engine (don’t get burned). (Stretching exercises before starting also help prevent back injuries)

2. Open the hood/bonnet and cover the pop-up lights with soft cloth. You might also want to cover the front wings /fenders.

3. Remove the central plastic air duct cover by turning the 6 small plastic clips so that the – signs are parallel to the sides (¼ turn) and inserting a small flat bladed screwdriver into the three clips at the top.

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These are the middle three arrows on the picture. Lift up and back to clear the front tongues.

4. You should now see all the radiators lined up one behind another. The engine radiator is the one at the back with its top hidden under the plastic fan shroud. The smaller vertical radiator attached to it with the screws is the automatic transmission cooler.

5. Remove the radiator cap (It’s on the expansion tank). Ensure the engine is cold or you might get a face full of steam = not nice.

6. Underneath the car. Remove the lower air spoiler by unscrewing all the screws and pushing towards the back (& slightly down) to release the hidden catches. (Don’t forget the 2 middle screws and the plastic clips in addition to the 3 screws on each side)

7. Underneath the car. Remove the engine splashguard that is protecting the front end of the engine. Both steps 6 & 7 are not essential but help a lot with draining and catching the coolant.

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In the following text # followed by a number is referring to the numbers on this diagram.

8. Underneath the car. Loosen the radiator drain plastic bolt (#2) with a large screwdriver so you don’t destroy the plastic. Don’t completely undo it yet. Get out from under the car. Replace the radiator cap and place a tray underneath the radiator drain. Reach underneath with a gloved hand and slowly unscrew the plastic bolt. Fluid will start coming out. When the coolant stream slows down remove the radiator cap and loosen the bleed valve. Let the radiator drain fully. Very little of the 13.5 liters (3.45 US gallons) comes out of the radiator (about 2 liters). Replace the drain screw and hand tighten. Empty the coolant into a bucket and reposition the tray below the expansion tank.

9. Remove the two plastic pieces (#9) at either end that are holding the radiator down by unscrewing the M8 (8mm) bolts (#12). Note that the design allows the radiator to move slightly and thus relieve stress even when the bolts are fully tightened. Use a socket extension to avoid hitting the light covers.

10. Unclip the fan shroud from the side air duct guides by using a flat screwdriver to release the clips. (the outer four arrows in the picture at the top). Use a small flat screwdriver to draw back the pin (#14) that is in the expanding rivets holding the top of the fan shroud to the radiator. With both pins removed, pull back and remove the expanding rivet where the pins were placed. You might need to coax it to come out.

11. Unscrew the small hose from the upper right (looking towards the back of the car) of the radiator.

12. Loosen the expansion tank bottom hose clip and move it towards the back. Reach in and unclip the large bottom radiator hose. Don’t pull the hose away from the radiator yet. (Depending on the position of the screw it might be easier to unscrew from under the car)

13. With a gloved hand slowly pull the expansion tank bottom hose back. Most of the coolant will come out now so you may need to hold the hose to control the flow rate so it goes in the tray and not all over the place. Some will spill – use some rags.

14. Empty the coolant into the bucket as necessary. Unclip the large top radiator hose and remove hose from the radiator. Remove the bottom radiator hose and catch the coolant in the tray. Allow to drain fully. You are unlikely to get every last drop of the coolant out. I got about 11-12 liters.

15. Stuff the expansion tank bottom hole with some paper to avoid drips.

16. Carefully lift the fan shroud with the expansion tank attached. It comes straight up and the small movement with the loose radiator is enough to let it come out without removing the fan.

17. Top of the radiator is now fully visible with the top two M8 (8mm) bolts holding the transmission radiator in place visible.

18. Look to the left side (looking towards the back of the car) of the radiator. There is a temperature sensor here (#5). Remove the electrical cable clip. (You might need to loosen the sensor slightly so it turns the cable clip upwards to make it easier.) Unscrew and remove the sensor.

19. Lift the radiator up a little with the transmission radiator attached. (Get help to avoid back strain) You will only be able to lift a couple of inches as the transmission radiator hoses start hitting the bottom of the fan. Reach down into the side of the radiator and remove the rubber foot (#8) from each side by pulling them downwards. Now you will find that you can lift the radiator slightly and push it back next to the fan. This will give you several inches of working room to remove the bottom two 8mm bolts holding the transmission radiator in place.

20. Remove the top & bottom bolts holding the transmission radiator. One of the bottom bolts will not be visible. Feel for it. The bolts are not highly torqued and come off easily. Take your time.

21. Lift the radiator straight up and out. You will see dish shaped retaining pads (#6 & #7) where the rubber feet rest.

22. From the old radiator remove the female clips (body nuts) for the transmission radiator bolts and the small rubber piece at the top of the radiator that protects the small hose from the expansion tank to the top of the radiator from chafing on the radiator metal. Place all in the same position on the new radiator. This is also a perfect opportunity to clean the area from where the radiator came out and check other hoses, connections and other fittings in this area.

23. Drop the new radiator into place next to the fan.

24. Re-attach the transmission radiator.

25. The Trickiest Step – Lift up the radiator and replace the rubber feet (#8) and drop onto the retaining pads. The pads are quite loose so be careful that they don’t move out of position and drop into an air duct or you’ll be going fishing. Additional pair of hands are useful

26. Replace the temperature sensor. I used some Teflon tape at the back of the washer to ensure a seal. Tighten and attach the cable.

27. Replace the fan shroud with the expansion tank attached. Make sure the tongues on the shroud engage in their counterparts on the radiator. (You do not want the shroud to hit the fan.) Also make sure the top small hose from the expansion tank to the top of the radiator is lying in top radiator channel and is not getting pinched. Ensure that where it moves back towards the shroud it lies over the rubber covered part of the radiator. See E31 FAQ for an excellent “How To” on expansion tank replacement. If you are going to change the expansion tank then do it while the fan shroud is outside the car – it’s so much easier!

28. Re-attach all hoses and secure with clips.

29. Remove the bleed screw from the expansion tank.

30. Fill with 1.75 US gallons (6.6L) of neat coolant. Now you have the minimum correct amount (50%) of coolant in the system. (I added almost 1.9 US gallons (7.2L) as some coolant is lost when bleeding the system. Top off & bleed with distilled water. You will need to do this whole step slowly. Take your time.

31. You won’t be able to add all of the coolant without starting the engine but don’t do it yet. Replace the bleed screw and the radiator cap and using a garden hose or a watering can thoroughly wash the whole area around the radiator. You want to dilute off and remove as much of the spilled coolant as possible so use lots of water.

32. Underneath the car. Replace the bottom plastic engine splash guard and the lower front spoiler.

33. Ensure all hose clips are tight.

34. Replace the middle air duct cover.

35. Follow the radiator bleeding procedures in the handbook and elsewhere on the Roadfly posts.

36. Inspect for leaks.

from e31faq.com

Interior:

1. Check the power seats on both sides. It's common to have the seat cable get bunched up and/or disconnect. It's a DIY or about $200 per seat, mostly labor.

2. OBC Pixels bad or missing. Also a common problem. I still haven't addressed mine. I don't use the OBC that often and can make out what is displayed. With some effort some E31 owners have been successful having BMW pick up the cost of the part and only paid installation. Some paid 50% of the part and split it with BMW.

3. On a '91 E31 the leather BMW used was very hard. The black leather esp. will look cracked and old. For about $50 a seat you can get the leather sanded and re-sprayed (dyed). I have done this to my black leather seats on the '91 I own.

4. Ashtray and coin holder lids broken or missing. Also very common. The coin holder design on the early BMWs was not very good. Fix it and don't use it. I removed my broken ashtray cover and use it as a cup holder since these cars come with very weak cup holders in the lower glove box ... which leads me to:

5. On a '91 you will have an upper and lower glove box. These are sometimes also broken at the hinge. Sometimes they are also not aligned properly. No big deal. Usually the two pop-up cup holders in the bottom glove box lid are broken and long gone... you're not missing anything.

6. Steering wheel rubber flex joint: I just learned of this myself. The E31 has a rubber joint in the steering wheel that will crack over time and allow play in the steering wheel or break entirely with potentially catastrophic results!

7. Auto up/down power steering function not working. Possibly a fuse sensor or worst case, controller.

8. Check all your switches and interior lights. Sometimes previous owners do not install BMW bulbs and use whatever they can get at the local auto parts place. For whatever reason (copper connections, etc.) the E31 is persnickety about the bulbs being only BMW. The light may work, but you may get a warning on the OBC (that is missing pixels LOL). I fought this demon myself with the brake light bulb and turn signal bulb.

9. General condition of interior. Check the headliner; open the medical kit and see if the door works, etc. You may also notice the seatbelts are integrated into the seats. The will auto adjust up and down with the movement of the seat. They will not work properly if the power seats are broken (see #1). You may also notice that the seatbelts are squeaky. Also normal. They rotate on a plastic-covered hinge that will start to get a cloudy gray film on them. The newer E31's came with a chrome-covered hinge. (Also chrome interior door handles). If the interior is in rough shape, chances are the rest of the car has not been cared for either.

Exterior:

1. The 8 sits lower than your average BMW even in stock form and the nose is quite long. The front bumper is integrated into the nose of the car. There is a black plastic lip spoiler that is at the very bottom of the car but is oddly recessed pretty far back form the nose of the car. Unless you really know the car, it's easy to rip off that spoiler on a parking curb. A valet or other non-owner driving, etc. will not know about this little detail. I have witnessed this myself as a passenger. $150 for the part and 8 sheet screws later all was back to normal.

2. Paint condition. You will be able to see very easily a re-spray on these cars since the odd angles and blending of the rubber bits with the steel are almost seamless. You will also notice a black rubber bump strip the runs down both sides of the car and blends into another bit of black seal between the plastic front bumper. Check the black strip and rubber seals for over spray or missed areas from being taped before being re-sprayed. Also check the front and rear plastic bumpers. Since they are the color of the steel body, it's a VERY tough job to match. You may notice some "stress rings" around the front Roundel. Also very common.

3. General condition. Again, lots of dents, dings, scratches, missing bits means trouble mechanically.

Mechanicals:

1. Loose steering. Could be the flex joint, steering box, adjustment nut, tie rods, any steering related bushings. The vague, loose steering is a common complaint on these older cars. It will not be as tight as your E36 as this is a GT designed for high speeds, but it should not have a lot of free-play in the steering.

2. Control arms and bushings. Very common on this and any BMW. The bushings for the E31 wear pretty quickly due to the weight of the car. It's a big girl. Heavy cars are hard on wear items. Ask if the control arms have been replaced/updated. '

3. DK Motors. Luckily (touch wood) I have not ever had any issues with these on any of my E31s. Do a search for "DK Motors" and read away. They just go bad. It's a common problem.

4. Heater Core. Check the A/C and turn it up. If you feel heat at your feet and coming through the windshield vents (either the driver's side or passenger's side) then you have a bad heater core. My last E31 had this problem. I used vent tape on the bottom vent until I came up with enough $$ to have to problem addressed.

5. Engine and transmission mounts. If the car shakes on idle but the engine is running smooth, you need to inspect the motor mounts. They are surprisingly easy to replace on the 850i. If you feel slight clunk when the car shifts (auto transmission) like the one you are looking at) then you may need transmission mounts. Again, they get old and wear. Engine is heavy, transmission is heavy. Did I mention this is a heavy GT?

6. Shocks. Not sure if this car has EDC, but regardless, if it has the original shocks then they will need to be replaced. Mine were so bad I could lift the hood on hard acceleration.

7. Headlight adjusters. The plastic adjusters WILL break if they are not already broken. Turn on the lights and check the alignment. You may be able to get BMW to replace these on their dime as well. Otherwise a member on this board sells a metal replacement similar to the upgraded metal units that BMW now uses to replace the plastic units. Do a search for headlight adjusters to get more info.

Here's a little list of what I have repaired/replaced on my "bargain" '91 850i six speed that had 104K miles on the clock. I paid $14,500 for the car in June 2004. All prices include labor or shipping.

Batteries replaced BMW OEM with labor (two in the trunk) $487.00
4 Wheel Alignment $99.95
Seat Repair and Dye (all four seats) $175.00
Black leather armrest for AutoChic $159.00 (incl. shipping)
Bilstein Sport Shocks $639 (incl. shipping) + H&R Springs (this is a mod) $176.00 + $300 install (springs and shocks)
Tie rods + Arm $523.16
Oil change (synthetic + filter) $218.04

Belts, Inspection II Service, AC compressor and retrofit kit from R12 to 134, upper control arms, lower arm bushings, radio code for radio, interior molding missing was replaced (below driver's side dash), repair sunroof not working properly, replaced A/C belts and adjuster pulley, two passenger seat cables broken, driver's side seat trim missing, installed new pieces, coin tray repaired, replaced front brake pads and rotors, replaced distributor cap due to bad fault, replaced ignition wires and ignition rotor, repaired windshield washer fluid sensor, replaced two cables in driver's seat for up and down movement, repaired vacuum leak at bank 2 with gasket for throttle body,

$4,494.05

Eisenmann Race Performance Exhaust (Round tips) $1622.22 + $200 install and custom fabrication of X-Pipe (replaced center resonator)

Replaced leaky radiator expansion tank $225.00

Full detail inside and out (the black paint was a combination of clear coat and none clear coat which suggests it has been repainted in some areas.. maybe a wreck, nothing in the history of the car. Since the clear coat black paint is just on the hood area, I think the PO just had the hood repainted to eliminate the rock chips these cars are prone to get with such a large swoop hood and nose). $125.00

Inlet hose replaced in cooling system. Had a crack and leaked. Hose, clamps, labor, etc. $107.00

BMW factory Anthracite mats front and rear for E31. $199.35

Window tint all five windows. $250.00

I have added some bits like AC aluminum shifter, factory leather shift boot, AC aluminum ebrake handle, AC aluminum pedal covers, aluminum door look knobs, and currently having a brushed aluminum dash kit installed. The black interior is really dark IMHO.

There are probably other items that I missed. Other owners can chime in and add to this list.

Bottom line is this: This is a GT! It's not going to drive/perform like your lighter and nimbler E36. This car as an 840 V8 or 850 12 cylinder has similar power and torque. One thing the 850i owners don't have the option to do is install an affordable off-the-shelf induction kit to our cars. There are some homemade options, but they are expensive. Dinan made a kit that is not even close to being affordable. The 840i however can accept a supercharger or turbo easily making it a screamer. Look up 840i supercharger for more info. The V8 in the 840i was a common cross-platform engine, so more modifications are available engine-wise. There are not any US-spec 840i E31s with a manual transmission however.

If you want a smooth, quiet, fast (not quick), unique everyday drivable exotic GT then the 8 Series is a wonderful choice. Unfortunately, this car was ahead of its’ time. There are many more high-line $100K+ GT’s to choose from these days (Bentley Continental GT, Aston Vanquish, DB7, DB9, MB SLC). The public fell in love with the looks of the E31, but not it's moderate stock performance. The looks of the car attract many buyers like you to take the plunge. Especially when the cost of these cars on the used market have reached an attainable level. The ongoing issue I see with the E31 specifically is that the new owner will not have the resources or time to restore the car to it's proper mechanical and cosmetic condition and it goes back into the used car rotation with potentially more neglect.

One last "gee Dad give me more advice" tip: If you can just barely afford to buy the car you are looking at, pay the insurance (which is quite high on the E31 by the way) and gas then I would not suggest that you purchase the 850i you are looking at. At $11,500 there are demons lying deep in the car. Trust me, I've done this 3 times now. Minimum I have spent is $5000 per car just to bring it to STOCK condition.

Good luck and ask lots of questions of the seller.

Sean