Quote:
Originally Posted by harshit
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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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.