| markrQ7 |
02-04-2017 01:22 PM |
Old/compressed gasket on PCV causing oil leak??
I have a 2007 Q7 4.2FSI with 70k miles and in the past few months, I've been churning through half a quart or more every tank of gas. The indy shop replaced the oil pan gasket for $1250 but it didn't solve the problem. I found many videos showing that the oil filter housing gaskets can be a huge problem so I figured I'd be in for another $500-$1000 job. In my case, I used a long lead USB camera to check the bottom of the oil filter housing and it's very clean down there. So I bought a new PCV valve (by the way, mine was covered in oil) and when I took it off I noticed how much play there was at the gasket by the pressure limiting valve where it attaches with two torx bolts. Comparing the new PCV and its gasket to the old one was like night and day -- the new red gasket was maybe 3 times thicker than the 10yr old one. I think the bad seal was allowing air to enter the system at that point and the whole crankcase ventilation system was no longer working -- the PCV was not depressurizing the crankcase. My oil was sludging up and there was no sign of fresh oil going down the flex tube that attaches to the bottom of the PCV (below the fine oil separator) -- that tube was totally dry. And I think that was allowing too much pressure in the crankcase which ended up pushing oil past the pan gasket. Should be a few days til I know for sure (we'll see it on the garage floor!), but it makes the most sense to me. Even the new oil pan gasket ($1250 wasted) is wet again which tells me the system was not working. Hope this fix works.... if it does not, perhaps that tube below the fine oil separator is clogged? If that's not it, I'm starting over.
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