Ahk noise

Zitat von bm840ci;89394

It is making an almighty noise when it comes into operation

Perhaps air in the system? Not enough pentosin? Did you bleed the system (with DIS or INPA)?

Zitat

or can it just be left off forever and ignored ??

If you don't mind having an expensive option permanently disabled, yes, it's fine to leave it off forever. When inactive, the AHK system has a mechanical lock making the rear-axle behave exactly like that of a non-AHK E31.

Mine is disabled on my csi (by Sytner), drives fine.

Zitat von bm840ci;89424

...where the hell do I take it...

Your best bet is probably to find a hydraulic systems reconditioner.

The AHK unit was (I think- check nameplate) originally made byMannesmann Rexroth and here's one that I just googled:

[INDENT]http://www.heavyparts.co.uk/rexroth.html

and aother link:

http://www.boschrexroth.com/bu…e-parts-catalog/index.jsp

[/INDENT]You could also try somewhere where they recondition power-steering systems.


(I recently bought a used unit to keep as a spare, but I might be willing to sell.)


Have you tried disconnecting the coupling arms from the suspension to see if it actually the hydraulic unit making the noise?

bm840ci: Good luck finding a place where you can have AHK diagnosed and serviced. The dealers know nothing about it. They'll just end up replacing every part of the AHK system until it works without really knowing what they are doing. While this may get the system back alive in its former glory, you'll leave with a mind-boggling bill. Sourcing parts or information through the original manufacturer, Bosch Rexroth AG, is a dead end as well - many have tried... Basically, you are pretty much on your own in diagnosing problems with the system. The hydraulic/mechanical part of AHK is no voodoo, though. As long as the electrical part works fine (which seems to be ok in your case - the slightest failure disables the system), locating issues in the hydraulic/mechanical part shouldn't be too difficult for anyone with experience in the field. Even though you will only be able to source parts through the dealer, several can be had cheaper elsewhere. You can have piping made to spec for a fraction of the cost, a good machine shop specialized in hydraulics should also be able to recondition several parts. It really, really helps when you have access to a BMW diagnostic system for AHK. That way you can test all components individually while not even moving.

Anyway, what was wrong with the AHK system in the first place? Why was it disabled or had it failed? Is there any reason to assume it has a mechanical malfunction? Are or were there any leaks in the hydraulic system around the AHK system? If the system was disabled for a very long time or hydraulic piping/filters were changed, did you properly bleed the system? If you turn the steering wheel (with the engine running) lock to lock, do you get a grinding sound from the power steering pump as well?

The actuator on the rear axle is the main component and if you remove its stainless-steel cover (4 allen screws), you will find that it contains a steel hydraulic block with 5 solenoid valves, each with two wires, all leading to the electrical connector block. The unit does not appear to contain any position sensors or other devices. The valves are screwed into the block and can be removed for cleaning (if not rusted and still in one piece). The actuator arms are partly covered by flexible rubber boots, which can be carefully removed for re-use later, but the overhaul of the unit should be reasonably staightforward (it would seem) for any experienced hydraulics workshop. However, the cleaning of parts and valves in an ultrasonic bath and the replacement of simple o-rings and seals may be the most you can expect. If there are any special seals or if the valves are damaged, then you may have a problem finding replacments.

Difficulties in dismantling may arise also if the unit is very corroded, in which case, careful sand-blasting prior to dismantling may help. I've seen some units so rusted that large bits of metal were flaking off with even the solenoid valve bodies in bad shape. (The stainless steel cover does not realy provide a seal.)

As Revtor commented, it may help to be able to operate the system through the test functions on a BMW diagnostics tester, to determine the source of the noise.

It may be that your system just needs a flush with clean oil, new filters, and proper bleeding, in which case it may be best not to dismantle the internal hydraulics, but just give it a clean and repaint. Filters and filter housings are apparently still available, but quite costly.

Quick question i couldnt find when searching; is AHK retrofittable?

Zitat von Adrian;89452

Quick question i couldnt find when searching; is AHK retrofittable?

In theory? Yes. In practice? Unless you have a donor car with AHK system in good working condition, don't even bother... If you don't have a complete system and have to buy new parts, be prepared for a shock: The actuator alone will set you back for over 6000 EUR, the control unit over 3000 EUR, the pressure accumulator over 1000 EUR,... VAT not included!

Well, I hope you can get it working. The previous owner of my csi went back to Sytners several times to try and get the fault light from coming up on the dash. They gave up after charging him lots and suggested disconnecting it, which they did! That's main dealers for you!!

bm840ci: What was wrong with the AHK system in the first place? Why was it disabled or had it failed? Did the AHK module's fault memory have any faults stored and if so, which ones? Is there any reason to assume it has a mechanical malfunction? Are or were there any leaks in the hydraulic system around the AHK system? If you turn the steering wheel (with the engine running) lock to lock, do you get a grinding sound from the power steering pump as well?