Foamy transmission fluid

[coldweatherblue]

Whats up revlimited. New member, just bought my second E30 (1989 AWII Coupe).

On the way home from buying the car I noticed an oil smell in the interior that I hadn't noticed when test driving it.. got home and there's some ? fluid leaking from the rear of the transmission. (reddish, clear fluid, smells like redline) Looks like it's leaking onto the guibo/driveshaft, exhaust, and rear of transmission.

Checked the tranny oil today.. it's a bit low, but the strange thing was that the fluid from the transmission is foamy.. almost like reddish shaving cream. As I understand this is air leaking into the transmission.

So I got a couple quarts of redline on the way.. obviously not going to drive the car in this condition.

My question is: If I drain and replace the fluid, is the car safe to drive? Assuming I check the oil level regularly. I'm guessing it's the rear main seal. I checked the overflow valve on the top of the transmission and it seems to be working. I'm looking to get an idea how much it's actually leaking.. I just want to make sure that the air leaking in won't contaminate the new fluid and fry my transmission.

Any other ideas on how to approach this? prolly gonna end up taking it to a shop cause it needs some other work too that I don't have tools for..

Thanks.

[nrubenstein]

The transmission is not sealed completely. There is a vent valve at the top that allows it to breathe. Air getting in does not cause foaming.

If I had to guess, I'd say that the car sat for a while at some point and water accumulated in the trans causing it to foam up while you drove it. Change all the fluids in the car and drive it and see if this recurs.

[E30 331is]

Maybe they put ATF instead of MTL. Depends on which transmission tag is on the the cover. Doesnt ATF get foamy?

[jlevie]

ATF or MTL can foam, especially if the transmission is low on fluid. Either will work just fine in a Getrag 260. As nrubenstein pointed out, the transmission isn't sealed and has a vent at top. A leak at the rear of the transmission will be the output shaft or selector shaft seal. Of if the transmission happens to be the transition variety which can accept either the sheet metal or aluminum shift console, a missing bolt can be the cause of the loss of fluid.

Replace the seals, and plug (with short bolts no more that 1/2" long) any holes in the rear of the transmission, drain and refill with fluid and see what happens.

[coldweatherblue]

ATF or MTL can foam, especially if the transmission is low on fluid. Either will work just fine in a Getrag 260. As nrubenstein pointed out, the transmission isn't sealed and has a vent at top. A leak at the rear of the transmission will be the output shaft or selector shaft seal. Of if the transmission happens to be the transition variety which can accept either the sheet metal or aluminum shift console, a missing bolt can be the cause of the loss of fluid.

Replace the seals, and plug (with short bolts no more that 1/2" long) any holes in the rear of the transmission, drain and refill with fluid and see what happens.

Thanks a lot for the replies everyone. Jlevie, are you saying it's okay to use ATF? I have some redline MT-90 on order because that's what I used in my old E30, but if I can at least drive the car and flush it with ATF while I wait that would be great.. any brands of ATF in particular? Or anything that I can get available at an autoparts store to put in my car so I can drive it.

btw the green sticker on my trans says: "Special Oil! HWB Best. - Nr 81228407305"

fwiw, I was told by PO that the car was originally an automatic and had a 5-spd swap done ~1 year ago from a junkyard trans.. so chances are good that it sat for a while.. and that the seals were not replaced when they swapped it.. :tsk:

Thanks!

Follow up: I was looking around the net and found this info:

-------------------------------------------------------------------------------------------------------------------------------------------------
B. Synthetic transmission fluid, Mobil SHC 630 (325e/528e without dual mass flywheel, produced before mid-1986).
Manual transmissions which are filled with Mobil SHC 630 synthetic gear lube have a green label with the words
“Special Oil” located next to the oil filter plug.



Note: Mobil SHC 630 is available in 5-gallon pails or 55-gallon drums from:

Mobil Oil Corporation - Contact your local Mobil oil distributor (see Yellow Pages) or call 1-800-582-3645.

Filling BMW transmissions with unapproved synthetic gear lubes could cause the following damage:

— Premature synchromesh ring wear
— Reduced service life of bearings
— Tooth profile damage
— Faster wear of selector forks
— Damage to radial shaft oil seals

Transmission gear clashing will eventually result.

Note: Do not use synthetic fluid Mobil SHC 630 in other vehicles. The transmission synchronizers of cars other than listed above are not compatible with synthetic fluid and premature wear will result.
--------------------------------------------------------------------------------------------------------------------------------------------------

Do you guys know anything about this? Are they serious that the transmission is designed for this specific oil and I need to buy a 5 gallon drum from mobile? lol thanks.

[coldweatherblue]

I'm ordering parts today to try to fix this.. currently got the output shaft seal, shift selector seal, and guibo in my cart. Anything else to replace while the driveshaft is off? Thanks

[blocke]

You could do new tranny mounts, and while you are in there rebuild your shift linkage or go with a short shifter. All the "while you're in there" items.

[E30 331is]

everything shifter related and maybe drive shaft bearing

http://www.pelicanparts.com/cgi-bin/...289%2F89-92%29

[SlamedIAm]

I'm ordering parts today to try to fix this.. currently got the output shaft seal, shift selector seal, and guibo in my cart. Anything else to replace while the driveshaft is off? Thanks

Be sure to get new lock nuts for the guibo bolts. You'll also need a new lock washer for the output flange after replacing the output shaft seal.

Now would be a great time to swap in a new CSB (get the whole kit with new circlip, etc.) and trans mounts if oil has been leaking onto them.

You may need new nuts for where the driveshaft meets the diff but I can't remember if those were lock nuts or not. I would assume so but I'm guessing here.

[coldweatherblue]

thanks guys.

Update:

after changing the old oil out for some valvoline 75w90 gear oil, I've driven about 50 miles and haven't seen any leak. The burning oil smell is much less now, seems to be just the remnants of where it had leaked on the exhaust before. So it seems the leak has either stopped or slowed with the oil change. I'm still planning on changing the seals out and filling it with redline MT-90 (got my parts from pelican in 1 day w/ free shipping!) but good to know that the car's drivable now..

interesting how much difference new oil can make too, second gear was really notchy before and now shifts much smoother, getting better the more I drive it.

Just goes to show how important it is to check fluids in a car right after you buy it, another hundred miles and i'd probably be buying a new transmission..