MrPDJ

I've done a little searching on other threads, but didn't come up with anything conclusive just yet. Hoping someone else has had prior experience and can point me in the right direction.

2011 A4 with 2.0L. 63k miles. Bone stock. Had the stage 1 oil consumption work done.

I noticed oil spots on the driveway the other day, so I started looking around for the source of the leak.

Oil does not appear to be coming from the front of the engine. That area is clear of oil. (oil filter, dipstick tube, front cover, etc.)

It looks like oil is dripping down in the middle. I see drops of oil on top of the "X" brace on the suspension. The leak/drips on the ground are about even with the sway bar/power steering rack, but no oil is present on those. It looks like oil drips down onto the lower parts of the engine and gets blown backwards onto the engine/bell housing. I removed the flywheel inspection cover and it looked very clean.

On the lower passenger side of the engine, I see some oil on the starter. Turbo lines look OK from what I can see.

Nothing is obviously leaking from the top side of the engine. Looked at PCV valve/hoses, but don't see anything obvious.

I purchased some UV dye to check it out further, but that won't arrive for a few more days. I was wondering what else I could check in the meantime.

If you have suggestions, I'd be glad to hear them.

Dr Awesome

Might be the rear main seal (aka rear crankshaft seal). Have you had a bad PCV at all? That can cause a RMS leak, sometimes it just shows up and a little oil will be seen under the rear of the engine.

MrPDJ

Looked again tonight and it definitely could be the RMS. The engine is shorter than I thought it was. I'm still puzzled that some oil is present in front of the RMS.

If if it is the RMS, it it totally shot if it is leaking or could a bad PCV be allowing the crankcase pressure to get too high and then it comes out the RMS?

Anything that can be checked on the PCV?

A few months back, the rubber diaphragm in the PCV was allowing air to get sucked in and it threw a code. I changed the diaphragm and that took care of it.

Dr Awesome

I think it is pretty much a must replace if you want the leak to stop. The PCV issue probably caused the seal to degrade, now it will leak until you get a new one unless someone gives you an alternative. I believe there are options out there for better than OEM ones (XLR8 comes to mind) to prevent the issue from coming up again, but it'll be a pain in the bum to do as you have to drop the transmission. It would be a good time to do the transmission filter if you haven't done it already since the x-brace has to come off!

MrPDJ

Providing an update in case someone sees this down the road. I had the rear main seal replaced with the XLR8 unit suggested by Dr Awesome. That stopped the leak. Hopefully won't ever have to replace it again.