Trans Breather Leak or Something Else???

#1

I got my car on the track last week for the first time after purchasing it. The car did not come with an extension tube on the trans breather nub. Previouse owner said it never puked oil out the breather for him. After the first shake down run the car quickly had a puddle of gear oil under it. Also the trans was covered including the slave cylinder. Too bad since the underside of this car was supper clean for a 20 yr old car. I also noticed it was dripping from a small opening in the bell housing. Seemed strange since its no where near the breather opening. Even after the car sat in my garage for a week it still dropped a drip or two from this opening and the rest of the trans was clean. See below for picture and finger showing the location of the drips.

The car was covered in gear oil area show below.

I added the extension tube today but am still a bit concerned since it came from the area in the bell housing. I am sure it was gear oil due to that lovely gear oil smell. I also thought I would have found more oil on top of the trans by the breather when I got my hand up there. When I checked the gear oil level today I could barely get my finger down to the level and when I dropped it I did not even get quart out. I also found lots of metal on the magnetic drain plug. Does everyone find metal on their drain plug during gear oil changes?

Could I have another problem going on I can investigate before shake down event number two? Don’t feel like spending a few hundred bucks and tow expense to have it still significantly leaking gear oil on track and puddling when I get off track. Not a good scene.

#2

Correct image for where the gear oil was dripping from.

#3

Looks like you have a leaky front output shaft seal (on tranny) or possbily rear main seal (around crankshaft). Either way, you will have to pull the tranny to fix it. If it is just a low level leak, I would wait until you have to replace the clutch, and do it then.
Ed

#4

Was the trans over filled? I think it only holds .9 quart…but I may be wrong. ed is right about the leaks, but I have never seen a front seal go on the trans…

Al

#5

What year is the transmission? Let me guess…89.

#6

Our 91 had a leaky front seal that we thought was the breather (or it may have been both). When we pulled the tranny to fix 4th the clutch was toast after being bathed in fluid for 1/2 the season.

#7

Mr. Junky has a leaky front seal. Very slow on the street. Fast on the track. Pouring out at Sebring.

Heavier gear oil (Swepco 201) helped during warm months.

#8

[quote]Looks like you have a leaky front output shaft seal (on tranny) or possbily rear main seal (around crankshaft). Either way, you will have to pull the tranny to fix it. If it is just a low level leak, I would wait until you have to replace the clutch, and do it then.
Ed [/quote]

That makes sense Ed. If I pull the slave cylinder and I get a peak in there or maybe an inspection mirror to see if its leaking from there.

No it was very under filled. I could barley get my finger deep enough into the fill / inspection hole to check the level. When I dropped the fluid it was way less than a quart. I think the trans take 1.32 qts according to Bentley so I was low to start with.

Yes it should be an 89 as the trans should be original to the car. It has the 17mm Allen plugs and no green or red stickers like others I have seen. Any issues with the 89 in general? Was it obvious its an 89 by the pictures.

Thanks for the input guys. Its a big help as I try to sort the car out.

#9

I have the breather hose in place now so I will see if that helps. I was going to put Redline MTL in but I do have a jug of Swepco 201. Maybe I will put that in to help slow it down until I can get at it this winter. Mid season trans removal is not on the to do list if possible.

Thanks,
Jason

#10

Don’t ask me why, but something about the vent on an 89 transmisson pukes oil at high rpms. For the last three years, my car has had a vent tube coming off the transmisson to a puke tank, which collects about 3/4 of the transmissions contents after a race weekend. Within the last month, I have installed a rebuilt 91 transmisson on my car. It is interesting to observe the difference in the 91 and 89 vent engineering. Obviously BMW knew they had problems to overcome, the vent is the only difference in the two model years.

#11

Gasman wrote:

I don’t know if this problem is related to the production date, or related to the condition of the transmission and/or lube.

My transmission used to leak fluid, which I’d catch by an artfully placed absorber. When I changed the engine last year I drained the drained the transmission while it and the engine were out before I looked to see if I had more Redline MTL. I had none, but did have leftover special Esso ATF as used in an E39 auto trans. I used that and haven’t lost any fluid since. Now I’m thinking that maybe Redline foams more than the Esso ATF and it is the foam that’s the problem.

#12

I hope my condition is not as bad as that but we will wait and see. Did you have the catch can in the engine compartment? It would be amazing it made it all the way up there in that quantity.

Jason

#13

The windshield washer bottle does the trick.

#14

Same leak on my transmission.

Input shaft seal has been changed twice.

It is not over full.

When the clutch starts slipping again, due to oil contanimation, I’ll check the inside of the gearbox housing for a “freeze plug” kind of fitting that seals the backside of gearbox internals as It was suggested that could be the problem.

Sounds believeable.

Regards, Robert Patton