Compression test?

flattype

New Member
Joined
May 11, 2006
Did a test on my 158k lower end 86t today. Heads have been done around 110k I think. Anyway 5 were around 145 and 1 was 130. I didnt think that was too bad... Thoughts?
 
From what I remember:
Warm engine.
All plugs removed.
Throttle wide open.
All cylinders should be within 10% of each other.
 
Those numbers are normal. That's where my untouched motor was at around 120k miles. Like previously mentioned, as long as they are within 10% of each other. If one cylinder is like 50 or something stupid like that...there's a problem. Compression test doesn't always tell everything but it's a decent way of seeing if there's a major problem or not. Sometimes you can have a partially blown headgasket and it won't come up on the compression tester. When you go into boost, you are making WAY more compression than just turning the motor over on a compression test. This is where a leak down test should be performed.
 
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