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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Mechanical Maintenance: Break-in / Oil & Fluids / Servicing / Warranty > transmission selector shaft seal oil leak



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      05-21-2010, 11:45 AM   #1
harshit
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transmission selector shaft seal oil leak

Hi Everyone
I have a 2007 328i, manual transmission, standard suspension
Miles: 68000
Car driven for 2.5 years

On a recent regular oil change service the dealership told me that I have a transmission selector shaft seal oil leak. The dealership has quoted a price of 610$ for the repair.

Is this a common problem? Has anybody here had this problem and if so how much did you pay to repair it?
Another BMW dealership told me that BMW has 'updated' the design for this seal and they said that they would install the newly updated seal so that this does not happen again. However they are the only dealrship that has heard of this updated design, which is weird...
Also can anyone explain what and where this seal is and if its very urgent to get this repair done? I drive 85 miles everyday.
The dealership told me that the manual transmission models have no sensors to indicate how low the oil is so he told me its very urgent?
I am surprised that such a leak would happen at 68000 miles I thought that the manual transmission is more reliable.anyhow...
Any input would be much appreciated.
Thank you
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      05-22-2010, 07:18 AM   #2
ENINTY
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The selector shaft seal is a small seal about the size of a quarter. It is located behind the selector shaft coupling. The coupling is where the gearshift lever arm attaches to the transmission from the gearshift lever (the shift knob in your car). Looking from under the car the seal is located above the transmission output shaft where the driveshaft connects to the transmission. The selector shaft is very short and is mostly just the coupling (it fits over the end of the shaft) and is right up against the top of the transmission tunnel. It is a close-quarters situation that is not easily accessible. To do the repair the tech needs to remove the center exhaust pipe, remove heat shields, remove the driveshaft (or at least disconnect it and move it out of the way), remove the rear transmission mount to lower the rear of the transmission, remove the gear shift lever arm, remove the coupling, pull the seal out, replace the seal with a new one (probably using a BMW special seal installer tool - or a big socket) by lightly hammering a new one in place, and then reinstalling all the parts just mentioned. There is a chance that the new seal will not go in perfectly and start to leak again. The selector shaft does not fully rotate; it basically slides fore and aft a few millimeters and rotates left and right a few millimeters. It changes the gears in the transmission. The selector shaft is about the diameter of your finger.

I doubt it leaks very much. There is not a lot of oil pressure in a manual transmission as the oil is pulled onto the gear set by the rotation of the gears through the oil bath in the transmission sump (i.e. there is no oil pump like there is in the engine). You could probably live with the seal leaking and just keep an eye on the transmission oil level at every oil change (opening the fill plug and seeing if oil drips out - 5-minute exercise). If it were me, I'd make them put the car on the lift and show me the leak. The most you'll probably see is the rear of the transmission will be "wet" with a coating of gear lube, I'd be hard pressed not to think it was the output shaft seal rather than the selector shaft seal, as the output shaft seal is a way more common failure.

If you get it fixed, take it to an independent BMW shop. It's not rocket science to make the repair.

Last edited by ENINTY; 05-22-2010 at 07:33 AM.
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      05-23-2010, 05:43 PM   #3
harshit
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THanks for the reply Eninty
I just had a few follow up questions
1) How could the dealership have known that the reason of the leak was this seal. From your post , it seems this seal is not easily visible. The dealership told me this leak was found during a standard multi point inspection?
2) According you its easy to find if the oil is running low, but the dealership told me that there is no easy way of telling of the transmission oil was running low in a manual transmission. Is this something I can do on my own by opening the hood? Where is the fill plug located?
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      05-25-2010, 04:28 AM   #4
ENINTY
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Quote:
Originally Posted by harshit View Post
THanks for the reply Eninty
I just had a few follow up questions
1) How could the dealership have known that the reason of the leak was this seal. From your post , it seems this seal is not easily visible. The dealership told me this leak was found during a standard multi point inspection?
2) According you its easy to find if the oil is running low, but the dealership told me that there is no easy way of telling of the transmission oil was running low in a manual transmission. Is this something I can do on my own by opening the hood? Where is the fill plug located?
After I wrote my response, I actually looked at my E90 while rotating my tires on this past Sunday. My earlier response was based on my knowledge of my E30 and my wife's Z3 (where I just installed a new clutch in last week), which are slightly smaller cars than the E90. All BMW manual transmission drivelines in the 3 series are pretty much the same design. So looking at my E90, I found there is a bit more space around the rear of the transmission, so it is a bit easier to see the selector shaft. You can actually see the seal pretty well, but the repair procedure is the same as I previously described. The seal could probably be replaced without removing the driveshaft, but it would lend to increasing the chance of not seating the new seal correctly and it leaking again. My car, at 111,000 miles, has a small amount of wetness around the rear of the transmission and the selector shaft was not dry (it would of barely stained a rag had I choose to wipe it off), but there were no dripping leaks per se. Unless the seal is really leaking badly, a small occasional drip of oil off the end of the transmission is pretty much normal and it would take years for the transmission too loose enough oil to damage it. Of all the cars I've owned and other cars I've worked on (probably 20 or so), not one of them had a completely dry rear end of the transmission, and all of them, when I checked (or changed the trans oil for routine maintenance), had no perceivable drop in oil level.
The dealer is correct in that there is no way to car keeps track of the transmission oil level from a sensor (because it is just not that critical to do so). The level can be only checked visually by removing the fill plug on the side of the transmission housing and looking at the level of the oil. The level of the oil should be at the bottom of the fill hole and should slightly dribble out. It literally takes 5 minutes to check the oil level once the car is in the air on a lift for an oil change. You can’t check it from under the hood.
If I were you, and it is understandable that you are concerned, take the car to an independent BMW mechanic and ask him if he will put the car on a lift for you and let you see how bad the leak is. If there is oil all around the driveshaft tunnel, where the seal is leaking bad enough to drip onto the output shaft and get flung off onto the surrounding undercarriage then you have an issue to take care of. If everything else is dry other than the end of the transmission, then it’s probably just normal seepage from the seal. Like I said before, any decent mechanic can repair this for you. It’s best to use an independent BMW mechanic as his familiarity with BMWs is an advantage.

Last edited by ENINTY; 05-25-2010 at 05:08 AM.
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      06-29-2012, 01:03 PM   #5
dreier_guy
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Selector shaft seal e90

Same issue here. My e90 was under warranty 55K KM. I remember parking it uphill and then I started having issues shifting into 1st gear. Left the car at the dealer and picked it up with the selector shaft seal replaced and fluid topped off. Never had any issues shifting since that repair. Just don't park uphill
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