Jesse729

iTrader: (2)

So I wanted to get some opinions on whether or not I would need a new engine or if someone can come up with some theory's to the problem of the oil burning and where the problem is.

The story. (2007 TL Type S 6MT)

A few months ago I had a spark plug, threads and all get, dislodged from the head. Cylinder #4 front passenger side. (Don't ask I guess it happens some times over torqued under torqued who knows) I took it to the dealership and they were able to heilicoil the head without removing it pretty affordably. They checked compression drove it and rechecked compression. They said compression checked out. The car seemed fine still seemed to be fine no issues and power seemed to be right where it always was.

The problem

It starts buring oil about a quart every 1500 miles which has now increased to about a quart every 500 less miles. I also am starting to get symptoms of lost compression. Loss of power at low RPMS and a little loss at WOT. It also smokes (Oil burning) at WOT but only sometimes. It does not smoke at startup

My findings
I did a compression test cyl #4 (bad cylinder) found a couple of things.

1. #4 had oil in the spark plug opening only but not much. (Where the ignition coil sits) (Oil returns quickly after only about 10 miles but it doesn't not seem to fill up the spark plug opening. (Only the bottom 1/2 inch of the coil seems to have oil on it )

2. I could not get the compression tester to seal on the cylinder air was leaking. Depending on if I got the tool just right I could get up to 150-160psi with a lot of audible leaking

3. Compression testing Cyl #5 (good cylinder) got 220-240psi tightening the compression tool the same way I got no leaks. As I was testing #5 I could hear the air leak in #4 with the spark plug torqued to spec.

4. Spark Plug in #4 is in good shape and is not oil fowled

5. Car doesn't leak oil

6. Replaced PCV valve which was clogged but no change in oil burning.

So I obviously know the the helicoil did not hold and is leaking and there is oil in the spark plug opening so it could have a bad valve cover gasket around the spark plug. I need to fix the head and get a good seal in my spark plug.

The problem is why is it burning oil? and is the compression low because the head is leaking around the spark plug or because the piston rings are worn and I am getting oil blow by in #4? I would hate to replace the front cylinder head and find that the piston rings are bad on #4 and have to replace the whole engine anyways. From what I have read 160psi on #4 could be acceptable on some engines and it must be lower to get oil blow by. Plus the tool is leaking so I would like to think that the piston rings are ok. It's impossible to tell how many psi is leaking from the head.

My only theory, and it is a stretch, is that because of oil leak around the spark plug and because oil is in the spark plug opening oil is sucked into the engine during vacuum and burned.

MarcDavidoff

Sorry to hear of your issue. Would it be possible that when that spark plug pulled the threads out of the head, that some metal bits could have gone down in the cylinder and did some scoring of the cylinder walls? And maybe that cylinder is now burning oil?

Adobeman

I don't think your theory is a stretch. Oil would get sucked in and burned. As to how it's getting in the tube it could be the suction is overcoming the tube seal and/or the tube seal is bad. Yeah, it could be rings but my money would be on the head. So I doubt it is a whole motor you need. With any luck it the insert can somehow be removed/repaired but I wouldn't be to optimistic about that. My guess is the head has to come out and be further repaired or replaced.