is there a difference in psi results. cause my car been sitting in the garage for 3 weeks and i did a compression test and it was average 60 psi. is that bad or does it vary with engine temp?

 

You have to have the motor at running temp. Doing it on a cold motor is pointless since it doesn't tell you anything. 60psi would mean the motor was done if it was fully heated up. Drive for a few minutes til it's up to temp and do it again

 

because my car wont start, and i was doing it at a cold temp. so low compression would be low if its a cold engine?

 

i do my compression test with a cold engine

 

You will get different readings for warm and cold engines, but 60 psi is pretty low in either case.

Are you testing with an open throttle?

 

no throttle just cranking

 

Test it again with the throttle open.

 

Compression test is done on a hot engine. This way all the parts expand on heat and keep a better compression.

 

I understand that the compression test is better done with the engine hot but if your engine isn't starting how do you do that? I just did a test because I think my headgasket is blown. I'm getting 105psi in each cylinder and the minimum is 135. I would have thought at even at 105 it would at least start. Also, it seems odd that I have low compression in each cylinder. Any thoughts?

 

If you ran the test with an open throttle, 105 psi is pretty low, even for a cold engine. However, it should still be able to start, even though it'll run like poop.

Sounds like trouble

 

X2 and 1st time I did a motor I didnt hold it WOT and i was like **** i need a rebuild. i was pissed and walked away for a second to get a drink and ran back out dugh it has to be WOT and then it was in spec.