Strange Leak Down and Compression
Thread Starter
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
Strange Leak Down and Compression New LS6 motor with JE pistons and Total seal rings, gapless top ring.
Five hours on it, including one SCCA race weekend. It runs great, plenty of power, idles good.
Here are the leak down numbers and compression test.
1. 5% 130lb
2. 3% 140
3. 3% 140
4. 5% 135
5. 22% 130
6. 5% 140
7. 9% 125
8. 7% 110
I freaked when I saw 22% leak on #5. I'm thinking broken ring. Then the compression test shows that it is not the worst cylinder. The leak test was with a warm motor, the compression was cold. Which one do I believe? Do I run it, or pull the heads. I set the lifters today before the compression test, and checked for broken valve springs.
What's up
Five hours on it, including one SCCA race weekend. It runs great, plenty of power, idles good.
Here are the leak down numbers and compression test.
1. 5% 130lb
2. 3% 140
3. 3% 140
4. 5% 135
5. 22% 130
6. 5% 140
7. 9% 125
8. 7% 110
I freaked when I saw 22% leak on #5. I'm thinking broken ring. Then the compression test shows that it is not the worst cylinder. The leak test was with a warm motor, the compression was cold. Which one do I believe? Do I run it, or pull the heads. I set the lifters today before the compression test, and checked for broken valve springs.
What's up
If anything cylinders 7 and 8 look down compared to the rest. Do the leakdown on 5 again to make sure it wasn't a fluke. Anything under 10% is usually deemed acceptable.
http://www.carcraft.com/techarticles...ak/index1.html
Notice what they say about a 20% leak
http://www.carcraft.com/techarticles...ak/index1.html
Notice what they say about a 20% leak
Thread Starter
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
That's good input. I did check the #5 two times, then again after I adjusted the valves.
It's still over 20%. I wish I would have known that tap on the valve trick when I had the valve cover off, I will try that one. Maybe drive it more and test again. I'm going to call the Total Seal guy tomorrow to get his input also.
Anybody else have good numbers from Total Seal rings, is this just a rare case of bad numbers? Thanks
It's still over 20%. I wish I would have known that tap on the valve trick when I had the valve cover off, I will try that one. Maybe drive it more and test again. I'm going to call the Total Seal guy tomorrow to get his input also.
Anybody else have good numbers from Total Seal rings, is this just a rare case of bad numbers? Thanks
