Jon; RE; Compression test;170 psi=good:25/40 psi=bad!!!!!!!!!
how did you do the compression test??????
I normally "run" the compression on all 8 cylinders "dry", then shoot WD-40 or a couple of squirts of engine
oil from an
oil can one cylinder at a time and re-check the compression on that cylinder.........if the reading goes up from the "dry" to "wet" run, then the problem is in the rings, if the reading stays the same and is still low, then the leakage is in the valves.................
If is was mine and you determined by the compression test that is stuck rings on cylinders 7-8, I would give it a dose of MMO and run it some miles, do this a number (5 to 10) times and re-check compression, you have nothing to lose unless you want to pull the motor and go thru it..........it may work and then again it may not, but it certainly is easier than pulling the motor and doing a rebuild................did I say I HATE pulling motors and going thru them!!!!!!!!! that's why I like to dyno my motors first or at least run them on a run-in stand before installing them, saves a lot of headache and you can find minor
oil leaks and fix them before intalling the motor in the car.............
David