I’m about to replace a blown head gasket and get a valve job, but I want to make sure the piston rings are ok before I remove the head. How would I do this? I’ve been driving on a blown head gasket for a while now but everything seems to be ok after about 2,500 rpms. TIA
first take a compression test on that cylinder. then take some motor oil (same rateing ur using). take like a tea spoon, just a little and dump it in the hole (spark plug). if the compression goes higher then ur rings are going. if the compression stays the same the rings are sealing fine. thats IF everything else is working fine.
All that a compression test will tell you is how much compression each cylinder has, nothing more, nothing less. It is a good way to check to see what condition your motor is in but I would recommend a leak down test over a compression test. That will tell you exactly where your problem is, if you have one and whether or not it is due to valves or piston rings.
Read this writeup on it, you will learn a lot.
Later,
BR