Compression testing

William Oliveri did pass the time by typing:

Dunno

You could. I usually do a quick comression test when changing plugs. Removing the plugs lets the engine crank easier.

Pull the fuse for your fuel pump.

Don't forget to disconnect the coil signal. :)

Till the numbers stop climbing (4-5 compression strokes)

fairly good although I'm not so sure about step3(running the engine with plugs loose)

Thanks,

I found in my FSM that the pressure for a 6 cylinder should be between 120 and 140 psi.

One thing I don't understand is why should the throttle be wide open position when fuel pump and coil are dis-engaged?

What does the throttle have to do with anything when testing cylinder compression?

Thanks,

Bill

here is how good ol' bob z. does a cranking compression check, but before i get into it, i would like to share something with you. a cranking compression test is just a tool used to quickly determine a difference between the cylinders. you are looking for consistency. a leak-down tester is the only way to know if you have engine or not:

1. warm the engine to operating temperature
2. pull all of the spark plugs (don't get burnt - be careful!)
3. prop the throttle wide open
4. screw the compression gage into the first cylinder
5. bump the starter over manually until the pressure peaks (a continuous cranking, approximately 3 -5 revolutions) - screwdriver laid over the posts on the solenoid or by using one of those really nice remote starter buttons (not the starter button that you use to start your car from the house)
6. record your reading
7. continue till you finish all cylinders
8. the cylinders should not vary more than 25lbs from each other.

-- bob z.

"people with less brain power than you are doing more difficult things everyday"©