Engine oil leak on AC compressor
 

Hi Experts,
I have a slow engine oil leak on the bottom of my 3.5L air conditioner compressor.. If I park car, the oil leaks about 4 drops per day onto floor. I cleaned the bottom of compressor, restarted engine, and the oil slowly started leaking. I could see the drop forming on the bottom (see photo), but could not see the origin; I suspect oil is seeping down the mating surface of compressor housing halves from above (somewhere near alternator).
https://cimg8.ibsrv.net/gimg/maxima....c923d83990.jpg
AC Compressor bottom

The oil leak is not near the oil filter / oil cooler/ or oil pressure sensor (those all looked dry). I just changed both valve cover gaskets, and the front valve cover (next to the alternator) does not appear to be leaking

Any ideas?

is the oil for sure dripping all the way down the compressor? oil pan looks kind of wet and might be misting/splashing some oil back, hard to tell with the image

Yes the oil is dripping down the compressor. After taking the photo, I wiped all the newly leaked oil off the bottom and sides of compressor. Without starting engine, I returned today, 24 hours later and the sides and bottom of compressor were again wet with oil.

I don't see a path from oil pan to upper compressor walls, so I don't see how oil pan could be source. The engine oil dipstick is above the area that leaks, so I suspect the origin is someplace near there, but it is difficult to see below the dipstick with the a/c pipes and alternator blocking the view (fyi the engine oil level is at bottom of dipstick). There are two pipes going to compressor from above (I believe refrigerant lines), and I suspect oil is leaking onto one of those pipes from above and that's what ultimately shows up on the bottom of compressor. I would suspect the oil is coming from the valve cover, except I don't see oil leaking there, and I just changed v/c gasket, and there should not be oil in valve cover after engine has been off for 24 hours.

I chose to replace the front valve cover (nearest the radiator) gasket again, because this seemed like the most likely source of a leak. After removing most RTV from the head with a gasket scraper, I finished with scotch-brite scouring pads which worked great. Then with a new Fel-pro gasket (and the original Nissan valve cover) I was more liberal with the RTV on the valve cover to head interface, adding approx 1/8" dia RTV bead. That did the trick, no more leak!