I just did a compression test with a piston tester. I held the check valve open like youre supposed to. I saw even pulses of 90-95 psi on all 6 faces. however both times when I let go of the check valve I saw 125 psi. how is it possible to see 125 psi if all 3 faces are putting out 90-95? is it that the bounces are just too fast to register fully on a piston tester and thats why I only see 90 - 95?

Thanks.

 

Obviously, when you're holding the valve open, you won't get a true reading, because air is constantly being vented out...so those numbers will be low. The important thing you're looking at there is that all the bounces are equal and there are no variations. Then the highest number which is what you get when you close the valve is the overall highest number for the chamber, and the number you should go by to assess overall health. IF all 3 bounces/faces were pretty equal in the first half of the test, then the highest number should be pretty much accurate for all 3 as well. BTW 125psi is excellent.