cold engine compression test

[Terry_H]

I checked the compression on my 86 GN today because my neighbor bought a tester off ebay and wanted to see if it worked. Cold engine cylinder compression ranged from 97 to 86 psi. Due to a fuel pump issue still pending, I can't warm the motor. Also didn't squirt any oil into the cylinders to help the rings seal.

Do the cold readings indicate anything amiss or are they meaningless and I should wait and retest with a motor at operating temp? Guess what I'm asking is, are these low readings about normal for a cold motor?

 

[mikestertwo]

They seem kind of low to me. Try another compression gauge. That one may be toast.

 

[Terry_H]

They seem kind of low to me. Try another compression gauge. That one may be toast.

It's schrader/valve stem that is supposed to retain pressure at the gauge. If I remove the stem, the gauge reads correctly, but obviously won't hold the pressure. With the valve it causes a 30-40 psi low reading. I even changed the valve with one from a bicycle tube, same thing. Anyway, I think my car is okay.

Looks like there's some original parts changed out on his Mac Tool compression tester kit. You get what you pay for....

 

[pajo]

compression

with stock cam it should be in 130's(+-)