So low compression means valve issues, could be
damaged or a bad seat also could be a bad head
gasket but most of the time a bad hg will show
other symptoms excessive steam from tail pipe or
emulsified coolant and oil. Could be bad piston
rings. You can test piston rings by doing a wet
compression test on cylinder 1 first do a regular
test and then add about 2 tablespoons oil through
the spark plug port and do the compression test
again. If compression jumps then you have failing
rings on cylinder 1 and the piston needs new rings.
Those are the more common causes of low
compression
3 people found this helpful.