How to test compression?
 

The tranny on my truck is nearly dead. The deciding factor of weather I'm going to fix it is the overall health of the engine of my truck. Since I bought it used, I have no way of knowing what condition the engine is in, but it seems to be running pretty good.

What steps are involved in testing the compression and what is a good range for the results? Harbor freight has the tool fairly cheap.

harbor freight has a diesel compression tester? you cant put a tester designed for gas engines up to the task of a ctd.
gas motors are around 150psi. the diesel is several hundred psi. the gasser model will explode.
but if its a diesel version, pull the injectors, ensure the shutoff solenoid doesnt get energized, and crank away.

Thanks for the reply. I meant to post this under 24v engine but accidentally posted here. Anyone want to move this?

you only need 2 or 3 revolutions to get your pressures. most of the time you can tell by the blowby if you dont have tons of blowby you more than likely are good on compression