Smoke from gearbox after hard acceleration

V8 or V12?
4.0 or 4.4l 5.0l, 5.4l, CSi.
Manual, auto, 4 speed, 5-speed, tiptronic.

Need more specific info on what car you have before anyone can help.

More info required......840/850, auto/manual?

If you overfilled the engine oil, why leave it? That can cause all sorts of major problems.

8Tech.

Zitat von Matt;101524

Sorry

5.0L V12 92' 850i

Well that narrows it down a bit.

Overfilled engine oil can blow sump gaskets, oil seals and throw oil straight into intakes.

8Tech.

Zitat von Matt;101521

On my 20-30min trip to and fro from work, I am finding that if I have accelerated hard to overtake someone at any point, when I get home and park the car, I get smoke coming form underneath the car around the gearbox area!!!
am wondering if i may have over filled it and possibly blown a seal etc?

Any ideas?

Look at the colour of the oil on the floor
Might be easier to dab it with a finger or white cloth
New engine oil would be almost clear or black with use
Auto fluid would be red
Either or is dripping onto the exhaust and burning as the exhaust gets hotter from use of the right foot
Should point to the culprit if nothing else

If you guys would have been more creative you'd have had a look at the few threads in the statistics of Matt, on the other hand, Matt, we are no visionarys
Beeing a victim of several M70 oil leak issues over the years I bet it's not a 4hp24-auto-tranny prob but a M70 gasket prob.
AND I bet that it is an upper oil pan gasket issue - bussines as usual

Unless you have a serious overfilled engine you're ok.
a moderate overfill (less than 0.5 liter) should not hurt at all.
As mentioned the crank case ventilation will send the oil into your intakes, which you would have seen on the exhaust if there was enough of it.

I would not worry unless you have overfilled the max mark with a liter or more.

I overfilled my gearbox by 0.5 liters a few years back, and it did not hurt that either, I asked a senior BMW tech and he said if you overfilled it would probably start shifting pretty hard, but should not damage anything.

I was thinking oil colour too, but I think the transmission oil I used the last time was brown too.

If it's smoking it's probably dripping on the exhaust, so that kind of excludes the gearbox as there is no place that can leak directly above the exhaust.

Oil pan seals won't have a leak that will drip on the exhaust either.
I'd check the rear of my heads, first the cam cover, as there are a few cracks it can leak from, the oil can then leak from the heads, run down the back of the engine and onto the exhaust.
the head covers has a rubber seal, so pressure may force the oil out just when you get to high RPM.

try to start your engine and pull the dip stick, if oil shoots out of it you will have a lot of pressure in your engine, and at high RPM it may be enough to force oil out through the seals.
There are small check valves on the DK-motors for the crank case ventilation, these are notorious to fail and cause over pressured engines.
Worth checking out.

Zitat von Noggie;101532

Oil pan seals won't have a leak that will drip on the exhaust either.

sorry Egil, my high-speed-experiences are different...

Apart from the fact that the visuals might give a clue about the origin of the oil I´m in with Harry. Oil pan leaks are just too common in the M70 and oil goes wherever the wind blows...

Cheers
Reinhard

Zitat von 8Harry8;101533

sorry Egil, my high-speed-experiences are different...

I've had oil on my exhaust at high speeds, but then we are talking 200+++kph.

Zitat von Noggie;101558

...but then we are talking 200+++kph.

correct!
Must have been in 2007 with about 155.000 km on the clock( guess so, I'm not a nitpicker) when the R129 CL500 that I had passed before @ 240 km/h or so could not be viewed in the mirror because of an oil fog cloud... - upper oil pan, what else

Living in Germany 200 +++ km/h isn't utopia, it's(still) business as usual!

Zitat von 8Harry8;101562

Living in Germany 200 +++ km/h isn't utopia, it's(still) business as usual!

It is in the UK too isn't it??

8Tech.

Anyone paid to have it done
How much does it cost to change a upper sump gasket ?

Over here it was a 2k job a couple of years ago in a 100+/hr workshop.
It is a bit involved and requires IIRC gearbox out, front axle (partially down) due to inaccessible bolts. Some US guys just pull the whole engine train.
Nothing you´d want to do on just a pair of jacks in your driveway.

Cheers
Reinhard

alternatively... - the holes are a bit big here but this method saves lots of money(if you find a dealer like mine is) and/or time.

Smaller holes here!