Getting a compression test...

[Brett Garret]

I'm currently preping my car for the cam I just bought. One of the things I have been interested in doing is running a compression test. The engine is entering its mid mileage area. Take in mind I'm not very keen on internal engine measurements. My questions: Where is a good place to have it tested? What's a good price? And last, would someone mind explaining what is good or bad for a 3.4L to run? Thanks guys. -B

[PiercedJD]

I don't know what kind of numbers you'd look for on your particular engine ( they will be listed in a haynes or chiltons manual for your car), but why bother paying anyone to do it?

you can get a compression tester for like $30 bucks at any auto parts store. all you do to do a compression test is:

a) disable the fuel pump
b) unscrew the spark plug on the cylinder you plan to test
c) screw the tester in in place of the spark plug
d) while holding the throttle plate wide open blip the throttle until you reach the compression stroke on the cylinder being tested. ( you will know because the needle will jump).
e) blip the throttle a few more times to get a final number, while taking note of how much the needle move during compression stroke.

move to the next cylinder and repeat.

if your compression is low, drop a little oil into the cylinder and test again. If it's a ring problem then the oil will usually seal the gap between the piston and the cylinder wall and drive the compression up a bit.

if the numbers dont come up with oil in the cylinder, then it's very possible you have a blown headgasket and/or bad valves/guides/seals