Help Locating Source of Oil Leak

[gulfcoastbeemer]

I'm having difficulty determining the source of a oil leak on my R1200RT.

Outwardly, there is a light -- not dripping, but accumulating, film of oil that seems to emanate from the top forward area of the transmission case -- which I believe, coincidently, is the location of a case vent.

In my attempt to find the source, I removed the body panels, but stopped short of removing the air box. I don't think you can see this vent without removing the air box -- but, I'm not sure.

Of course with the influence of gravity, the oil finds it way down to the base of the engine; but the fact that there is oil all the way to the top of the transmission case leads me to believe the source of the oil might be the transmission/gear case vent.

Does anyone have experience with this problem? What would cause oil to find it's way out of this vent in sufficient quantity to have it accumulate on the sides and bottom of the transmission case, and then down to the engine base?

I using BMW Synthetic Gear Oil 75W140 in the gear case. When I opened the fill plug, I noted the gear oil level had dropped slightly over the last 12,000 miles. I was able to add several ounces of oil -- perhaps, the same few ounces that puked out the vent.

Any thoughts?

I'm hoping this oil leak isn't one of the main seals, and I'm a little doubtfully that it is given that the oil seems to start up to the top of the transmission case.

[mtboulder]

What year is your RT? I've seen oil leaking from a '05 R1200GS through the top vent on the gearbox. The top of the gearbox was basically coated in dirty gear oil but did not leak enough to drip on the ground. I've heard that BMW made a change to this setup to prevent further leaking. There is a rubber push on vent cap on top of the gear box about 3/4" square (although the vent is more rounded in shape). If it's gear oil that's leaking the other possibilities are:

1) rear seal where the clutch slave cylinder attaches. On the '05 GS this was also leaking.

2) Rear output shaft seal. This would cause leaking inside the front rubber boot where the driveshaft housing attaches to the gearbox.

3) Input shaft seal which is located in the front of the gearbox. If this where leaking then it would likely contaminate the clutch.


4) There's another seal in the front of the gearbox. I forget what it's for but it would also leak in the clutch area and likely effect the clutch.

Sounds like yours is either the vent on top of the clutch slave cylinder seal.

If it's the vent on top you might try switching to 75W/90 gear oil to see if that helps. I think the (less than clear) spec calls for 90W and not 140W although I run 75W/140 with no issues in my '06 RT.

[dzimbric]

I noticed a similar condition on my '05 R1200GS. Had it in the shop and they said it was not coming from the trans or getting on the clutch so maybe I have a vent issue.

What is the fix. I just clean mine when it starts to bug me. Have not hasd to add any fluids.

[tbryant]

My 06 RT was thought to have the dreaded trans input seal leaking, which isn't uncommon for I believe 05 thru early 06. I've cleaned it well and 7K miles later is still clean. Dealer said there were some vent issues and could have been the cause. It appeared as a "beard" of black greasy dirt along the seam at eng/trans. Has never come back but I keep an eye on it.

Terry