What could be leaking oil here?

Hi All, Please forgive me as I'm still getting familiar with all the bits and pieces of the 996 engine. I've taken a couple photos to show this leak and I'm having trouble finding a diagram of what exactly I'm looking at. So, what is it that's potentially causing this oil leak, and, how do I fix it? Thanks, Mike This is looking at the rear of the passenger's side of the engine from under the car. I had my camera in between the rear bumper and the engine block. This is trying to get a photo of the leak from the top. Unfortunately it is blocked by a large coolant hose and its hard to get good light on it....

Looks like the AOS vent valve on top of bank 2. What year is your 996?

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Thanks! 1999 C2. I just swapped out the AOS as I have the transmission out. So this is an oil hose that connects to the AOS?

Yes, part #6 (the 1st occurrence) here http://www.autoatlanta.com/porsche-p...section=104-10 Also two o-rings (Part #22) at both ends of that hose. I stole a pic from eBay

Thank you Ahsai, So it looks like replacing 6, 7, and 22 is probably I what I should do. Mike

Yes and #7 already comes with #6 (click on #6 to see its photo).

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Just a heads up, while those parts are purchasable separately i'd just purchase number 4 on the diagram as it comes with parts 6, 7, 4 and 22 (hose, seals and ends). The hose itself also becomes crusty with the heat cycles and develops holes and its near impossible to get part number 6 off the hose without breaking it. I tried to get it off my old hose and it was so brittle it cracked and fell apart breaking the old hose. The installation of #4 is quite straightforward: 1. disconnect hose from AOS 2. Remove airbox, throttle body, T plenum 3. Remove old hose 4. Cut cable tie holding hose to 2nd resonator (top of engine) 5. Undo 2 bolts on bank 4-6 6. Remove hose 7. Feed hose through left side engine and bolt to bank 4-6 8. Run AOS end through engine down past coolant tank - connect to AOS 9. Cable tie hose to 2nd resonator (smooth section of the new hose where the tie should go) - cable tie is 6mm in diameter and quite long. 10. Reassemble Tip: make sure the hose doesn't come in contact with the coolant tank sensor, I think over the years it caused a hole in mine. Alternatively you could possibly use a 997.1 hose (un-confirmed but all seems to point towards being possible) it's much more robust however is around 3x the price, I opted for the 996 hose when I did mine.

dan-189, Thanks for this. I was hoping to avoid removing the plenum, but, its probably a good idea to replace the hose... How long does it take to remove the plenum? Is it quicker to drop the engine to do this? Mike

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No problem mike, it's daunting at first to remove the plenum but soon as you've done it once it doesn't seem so bad. I had the same hesitation when I needed a new starter cable. Had the dealership do it but whilst I was poking around doing this job I saw I could have tackled it myself! Anyway back to the plenum you'll have it out in 30 mins at most. Here are the steps: - disconnect MAF (has a clip underneath squeeze the clip the cable will unplug - next undo the two clips holding the MAF cable against the airbox - difficult to see but follow the MAF cable you'll see them. They come apart by splitting them open in two. - remove the jubilee clip around the airbox to throttle body and remove rubber boot from throttle - undo the oil filler neck from the airbox - pull airbox out - unclip AOS hose to plenum - remove vaccum line to plenum - undo 4 jubilee clips for plenum - rotate plenum to break seal and gently remove one side out and the rest will follow. This is definitely an engine in place job, access is limited but it's easier than dropping the engine. Only tip is to have someone with long thin arms around to help reach the rear of the engine.

It will be interesting to see if that fixes your problem. I have the exact same leak. The dealer diagnosed #6 in the diagram had to be replaced. Seemed OK, but a while later the leak came back. Dealer said the new part was probably bad, and replaced it again (free of charge, covered under the 1 year parts warranty). Same leak occurred a few months later. Dealer said the leak is at the head, and they would need to do a re-seal for a very expensive amount. I declined, and have lived with the leak for about 4 years.

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Quite difficult to see if the hose is in good condition or not unless it's actually leaking quite badly. I have a feeling my hose had been leaking for quite awhile but never produced any drops on the floor. Was only when I was inspecting my engine mounts that I saw it was wet with oil.