I have been burning a small amount of oil lately, mostly at low loads. It will boost up to 10 psi and the power feels normal and there is not a puff of smoke behind me but at idle, I can smell it and it will let out a small puff when I give it a little gas but not every time. So I check the intercooler piping and downpipe for any signs that my turbo seals are bad and they look fine. I then run a compression test and the results are not good:

1: 180
2: 120
3: 180
4: 180

To make sure the tester wasn't bad, I ran cylinder 2 again...same result. Then I tried a wet test...same result. I figured broken ring lands but I wasn't smoking out of the valve cover.

I spent Friday afternoon breaking down the engine. The headgasket looked pretty sad since it was a reused one sprayed with copper (but I have a brand new one ready to install), but I wasn't displaying any signs of a bad headgasket. I was surprised when I pushed out the troubled piston and there was nothing wrong with it...the rings looked great and the ring lands were all intact.

So what is the problem? Valve stem seals were replaced within 10,000 miles, valves look good, turbo has less than 3,000 miles on it. I have pretty much decided that I am going to rehone, rering, replace the rod bearings, and headgasket and hope the problem goes away. Any ideas?

 

Well if all the components you mentioned were good, There are two things I would blame off the bat.

Bad headgasket, Bad valve seat and/or warped valve.

 

If it passed the wet test with the same result, then I'd be looking at a bad valve, valve seal, or headgasket. Sounds like you've already checked those off your list. I'm not sure how to check a valve seat, but since it sounds like you've got the head off already, try putting some water in the combustion chamber of cyl. #2 (head upside down obviously) and leave it for a few hours, see if any of the water (or some other fluid) leaks past the valve.

It's also a good possibility that a re-used headgasket + boost just wasn't up to the task. You could be mechanically fine, and just need to put it back together with a new HG.

 

Sounds like I need to inspect the valves a little more to see if I can rule them out. I'll try the water method and see if I have a seating problem.

Thanks for the insight, guys.