I have a slow oil leak at the rear of the engine in my 2003 A4 1.8t Quattro Avant 76,000 miles. Leaves a 2" stain or two (drips from two places, a couple inches apart) wherever I park, but dipstick level remains almost completely stable — so far I haven't had to add oil.

I have been trying to track down the source of this leak. I have thoroughly cleaned the engine and undercarriage (and areas under the oil filter that were messy from oil change spillage).

There is no obvious leakage above the bell housing (valve cover gasket, head gasket, etc.), and the picture below shows where the oil is pooling and eventually dripping from.


(photo taken from underside, straight up at bottom of the front of the oil pan and part of bell housing)

I took it to a mechanic (not an Audi specialist) and he said he couldn't find the source. He thought it might be the rear main seal. My research into B6 A4s indicates this would be rare but not unheard of; however, someone in another thread/forum commented that the flywheel would be oily if it were the rear main, and the teeth I can see from the underside are dry. It doesn't seem like oil is being "thrown around" down there, although it is spread around a bit (wind? vibration?).

I'm hoping it's not the rear main, because I'm disinclined to pull the transmission for a tiny leak like this. I'll probably try BarsLeaks or similar until the thing drives me crazy. Any thoughts?

 

Hi, did you resolve the oil leak? We have exactly the same leak but Audi garage can't be sure until they take it apart! Please could you reply as soon as possible. Thanks, Peter.

 

I have the identical leak. I am going to check out the seal on the back of the camshaft as it appears to be on the starter as well.

 

my 3.0 has a valve cover gasket leaking slowly and a crossthreaded drain plug, it leaks a little but not enough to actually drip. I don't know if the turbo has anything to do with yours.

 

hey mate,

what did this end up being? I just did a clutch job and an exhaust upgrade and now left with a slow leaking trany, not sure what the issue is yet.

thanks
payam

 

NOTE: Mine is a Tiptronic.

Took it to a local mechanic, and they weren't sure if it was the rear main or the upper oil pan (both $$$ repairs). The mechanics there (very experienced Audi mechanics) said they had NEVER seen a stock rear main leak in an A4 1.8t.

When it went from a slow leak (2 drips) to a dramatic stream, I dropped it off and the plan was to do the oil pan, but they dropped the tranny and immediately found the source was the rear main.



In the end, the only two places that leak could have come from were the rear main or the area where the oil pan gasket buts up against the tranny. If you're getting oil dripping from between the transmission oil pan and the rear of the engine block, and there's no evidence of oil from above (cam seals, valve cover gasket), it might well be the rear main. I got some good advice on other forums about trying to isolate cam seal leaks, which are pretty common. I'd eliminate those as a possibility before dropping the transmission or subframe.

 

Hi, I have the same problem with my 2011 Q7. Does anyone know whether the gearbox can be removed separately to get at the rear main seal, or does the motor and trans both have to come out?