Here's a quick summary. New motor, with close to 11:1 compression. Car was not boosted yet, and has approx 5k miles on it. Shot 275 across all 4 cylinders under the compression test. Car was detonating plenty, next thing we know the compression is 160 245 245 245. So I'm assuming #1 rings are gone. So we're going to just swap out all 4 rings just to be safe. The car burns up the 10w30 about a 1 1/2 quarts a week. Blown headgasket wouldn't happen minimize the compression on just 1 cylinder would it?

 

add a little oil to cylinder #1 and do another compression test. If your numbers come up you know it was the rings.

 

detonation takes out the weakest link in the sys. that it has acess to

 

thanks! going to do it now

 

Detonation will usually take out the ring lands too if its severe...so just replacing the rings wont be a viable option if thats the case(assuming that's the problem).

A failing head gasket can also be the culprit and can effect just one cylinder...

You can compression test it and it may give you an idea, but its probably going to require a tear down to be sure...

 

If you did a leak down, you would know where the problem lies.

 

Yup, just do a leak down and it'll tell you exactly where the problem is.

-Mike