I rebuilt my engine last winter. After the initial break in, I noticed a small leak from where the engine case and transmission join together. I assumed it was a rear main seal leak. I drove it for about 100 miles since it wasn't to bad, hoping it would clear- it didn't. I took out the transmission and inspected the rms. It was perfectly alinged and I did not see any source for the leak. I replaced the RMS since I was in there. Even after the RMS replacement- it still leaks slightly. It hasn't been a huge deal. I have never noticed a decrease in oil level on the dipstick- its just very annoying cause it drips on my headers.

A few notes-
-definitely engine oil leak- oil is green, I am using Brad Penn oil
-oil galley plugs were replaced during the engine build and are bone dry
-engine runs extremely well
-case was check and within specs prior to rebuild.

Any ideas on what could cause this chronic leak? Is it possible that my schadeck 30mm pump is making the oil pressure too high and therefore causing a slow leak?

Did you put the o ring on the flywheel?

O-ring?

021 105 279, it goes on the flywheel by the RMS.

#3

The o ring is in there. It's not twisted either. When I replaced the rms I also re replaced the o ring.

Did you put sealant around the RMS before you seated it? Can you tell where the oil is coming from? Is it from the ID or OD of the RMS? Not coming from between the case halves?

Appears to be from id of the rms. od seems pretty dry for the most part. It doesn't look to be from the case halves.

I had the same sort of problem with the rear seal on my last engine rebuild. A new Victor Reinz seal solved my leak.

There is a bus supply (Westy?) that sells a rms that is slightly larger. $49 + shpg

Dr. - where did you get that cool exploded view pic with torque numbers?

That's from the T2 Robert Bentley manual. Pretty good for T4 engine work. It's the VW Factory authorized book.

The Cap'n

The rear main seal isn't directly exposed to pressurized oil, so high oil pressure isn't likely to be an issue there. I've seen engines where the drain passage behind the seal is filled with whatever sealant was used on the case halves and doesn't allow the non-pressurized oil behind the seal to drain back into the sump. Assembling a case without paying particular attention to that passage is a good way to create a mystery leak.

The Cap'n