dgdsm
10+ Year Contributor
- 173
- 4
- Aug 24, 2008
-
Tarzana,
California
As part of tracking down a recent cooling systems problem that cropped up, I did an engine compression test to check the HG. The numbers came out similar to what I got last time: 200-210psi. It’s possible that I need a new compression tester, but how much is excessive cylinder compression a problem and where does this come from? I guess the shaving off of a few mm of aluminum when the head was resurfaced could be a part of this, and I think the 4g64 has normally has a slighter higher normal compression than the 4g63. One problem that is happening is that I have some leak at the spark plug well gaskets, and oil is pooling up in the spark plug wells. I usually try to soak up the excessive oil with a paper towel, but I know some is getting into the combustion chamber in the compression test. Could oil in the combustion chamber raise the compression by 50+ psi ? My LTFTs have been running at around +7 to +10 at idle, so running lean might be a bit of a problem.
The good side of this is, I’m reasonably satisfied that I don’t have a leaking HG and replacing the ECT sensor has taken care of most of the cooling system issue. It’s possible I have a cracked overflow reservoir and the engine is losing coolant there.
But I’d like to track down this possible excessive compression issue and whether it might be affecting engine performance.
The good side of this is, I’m reasonably satisfied that I don’t have a leaking HG and replacing the ECT sensor has taken care of most of the cooling system issue. It’s possible I have a cracked overflow reservoir and the engine is losing coolant there.
But I’d like to track down this possible excessive compression issue and whether it might be affecting engine performance.