exactly how to compression test pistons?

[4byRANGER]

i picked up a compression tester, i know i hook it up to the spark plug threads until semi tight.. now do i want the engine completely running or just turn in over slowely?

 

[TomB1269]

Just turn over, do not run.!!!!!!!!!!!!!

 

[Sasquatch_Ryda]

Disconnect your coil so the engine won't have spark to start. Crank it over for about 4 to 5 seconds per cylinder.

 

[4byRANGER]

awsome thanks alot guys!

 

[Rearanger]

Engine hot also.

 

[Shamus]

If you pull all of your plugs the engine will spin easier. As said above, your engine should be fully warmed up before testing. The internals will expand to give you the proper reading (high or low) and your cylinders will be oil coated for a ring seal. I am a little concerned by your statement of "semi-tight". It must be tight enough to ensure a complete seal against air escaping. Luck!