Comression test numbers
 

I have a quick question for the brain trust...
I just ran a compression test and got the following:
#1 155 psi
#2 160 psi
#3 140 psi
#4 155 psi
The difference between highest 160 psi and lowest 140 psi is 12.5%, which is higher than 10% (number quoted often as being in specs).
My question is do I really need to tear into the head gasket/vales ect. for this differential ?
I don't wanna :(
Sox

Throw some oil in number 3 and report back.

Two things: Was the conmpression test done on a warm motor? Have you considered a leak-down test (will tell where compression is being lost)?

Peter

Did the "wet" teaspoon of oil in the cylinder, compression went up to 180 psi...
Looks like piston rings ??
Sox

Test was done on a cold motor, Will do a leak down test next.
Sox

Yeah. Rings are a little worn… almost a 40 year engine…

What’s your oil pressure? Burns oil?

Is a waste if you got your compression up on a wet compression test. You know you don’t have a bad HG or burnt valves….

concur, Will run a hot engine compression test after the car is running again.
Thanks
Sox

Is it running badly? If not... let sleeping dogs lie.

It's running fine, just chasing a 12psi boost issue...used to be 14psi.
Sox

i'm pretty sure the lower boost is not because of the compression issue because i've seen 951's with even lower compression making over 21psi of boost.

Nize, you are correct, it is not likely. I was just doing a general health check on the car. I also am getting the injectors cleaned and refurbished at the same time.
I am pretty sure the missing 2 psi are related to the massive leak at the ICV.
Sox

I just inked a deal on a new to me 89. I had compression testing done on it and it came back within 1% thank god. Gonna have a mechanic tear into it yet? ��