ct636

Hey all. I bought a used 2007 S6 V10 and have been chasing an oil leak. I have already replaced the valve cover gaskets and the oil cooler seals, all done by the dealer. I still have an oil leak at the rear RH (Driver) side of the motor. It is running down onto the cat and smoking. The dealer is suggesting to pull the motor to find the issue, however I really do not want to. I know the oiler filter house seals are a common source, but that they normally run to the front of the motor. Does anyone have any experience with the seals leaking and the oil running to the rear of the motor? Thanks.

raj99

might be the figure 8 o-ring as described here: https://www.audiworld.com/forums/a6-...-leak-2915411/

you'll need to remove the manifold to determine.

ct636

Does that failure present at the rear of the motor as well as the front? I am really not interested in pulling out the motor, and I know I can do the O rings with it in the car.

raj99

Did you read the link I sent in my original response? The first line says "The leak with my concern is located somewhere on the upper rear of the engine"...

ct636

I did read it. Although there is no response confirming that this was the leak he had, and confirming the replacement of the O rings fixed it.

froggers4

OP, there is no pathway for the oil to reach the back of the engine if the oil filter housing seal is leaking. If you are absolutely sure that the oil is running down the back side, then you'll need to look elsewhere. Another potential location for leaks is the upper timing chain covers on the back of the engine. These sit directly over the exhaust system. The bad news is that they require an engine pull to reseal.
However, based on the number of failures of the oil filter housing gaskets, I would still advocate for pulling the manifold, or getting a borescope to look in the valley for oil.

ct636

Well I borrowed a bore scope from a friend today, so hopefully I can have a look this weekend and see something either in the valleys or down the back side of the motor.

Mark Patterson

I too had the dreaded smoking stinking leaking onto the exhaust and cats that nearly had me sell my car. After much and I mean much disassembly and repairs the problem ended up being the cam position sensors on both sides which are placed adjacent to the oil filter housing mentioned in this post. In my experience the oil filter housing seals do leak mine did but that oil ran out the front of the engine. This leak is definitely down the back and sides of the engine onto the hot exhaust. I had thought that I could and would seal them up with the audi spec sealant that is used for the oil pan - did I mention that I sealed that up as well before I discovered the oil filter housing leak - but this did not work. Audi sells oil sealant rings for the cam position sensors for a couple of bucks each side and while they look cheap and you would assume they would not work as well as the sealant trust me you would be wrong and once the sealant is used it is a nightmare to clean off when you do decide to use the Audi rubber ring seals from the factory. After this repair I went on to replace the entire drivers side valve cover as their is a defect in it which prevents it from sealing properly after a few years of heat cycling and mine now seals properly. This can also contribute to pil leaking onto the exhaust but in ky case it was definitely the cam.position sensors. I also ended up replacing the two hair thin o rings in the balance shaft cover on the front of the engine, the front main seal which requires a special tool from Audi to install properly - don't waste the seal trying to do the repair without it I did try it and ended up with a messy leak in spite of it looking perfect once installed and last but not least the passenger side valve cover gasget which in contrast to the drivers side cover is not under a recall for cover warpage and can and does seal properly with just the replacement rubber seal go figure. If you have any other oil leak questions or any other general questions on the V10 C6 S6 I have I think at one time or another been through them so I will give you my two cents worth should you wish. Good luck with the oil seals on the cam position sensors.

Mark Patterson

Sorry but I have to follow up and correct a mistake I made in my earlier reply it has been a long day. I mentioned that it is the cam position sensors which are causing the leak you are describing and this is incorrect in name only.

It is the camshaft position adjusters which are causing the leak and not what I described earlier as the camshaft position sensors. To be clear there are camshaft position sensors on the V10 but they rarely if ever leak. It was the camshaft position adjusters that were the culprit on my engine leaking oil onto the exhaust at the back side of the engine on each cylinder bank. I actually described them in the correct position on either cylinder head bank placed on each side of the oil filter stand in the V of the engine if you are looking from the top down. The camshaft position sensors are cylindrical in shape maybe 2 and a half to 3 inches long and 1 inch across They actually use the engine oil pressure to advance or retard the timing of the camshafts and as such adjust the flow of air and fuel into the engine based on RPM and if course oil pressure.

They are accessible by removing the throttle bodies and intake manifold on my V10 but I can not be certain of where they are located exactly on any other engines. However they are always valve train related and mounted somewhere on the cylinder head usually one on each side in the valley of V shaped motors and on the side of the cylinder head close to the camshaft drive on online motors. Googling camshaft position adjusters for your particular motor will show you quickly and easily where they are located.

Please allow me to apologize again for calling them by another incorrect name. PM me if you have any other questions regarding oil leaks on the V10, my own personal experience and in wrenching on my car myself has made me somewhat of an expert on V10 engine oil leaks!!

ct636

Mark - Thanks for all the info. My issue ended up being the valve covers (replaced the driver cover and the passenger gasket). I originally had an Audi dealer do them, and continued to have smoke. After some back and forth between the dealer and I, they replaced both covers (not just the gaskets) under warranty from the first repair. I think I am going on about 3 or 4 months no with no issues.