How do I do a compression test on my car engine?

Question

Is there special mechnical knowlege needed?

thank you, rhythm. I have no particular problem with compression that I am aware of. But I do have an
straight 6 (ford 300) with 150K and
I'm merely curious. However, I do have a problem with the lifters clacking for a few moments after first
starting a cold engine.

Answer 1

Not if all spark plug sockets are easily accessable.

Buy a compression meter, find a way to disable your vehicle so that it wont start (wire to distributor for example) Unplug plug #1 and insert compression meter. Have a friend watch the meter, crank the motor until the needle stops going up. (takes a few seconds) Replace #1 plug and move on to #2 and so on....

Check a manual for allowed deviation between cylinders. They should all be fairly close.... if one is definatly out of range you have found your problem. (all cars have some deviation)

If you find a cylinder that is low, try putting a bit of oil in the cylinder and cranking the motor... if it raises its probably a piston ring. to know for sure where your problem is, you will want to do a "leak down test" I'll try to answer that one later.



(not sure why the guy below me said dyno)

Answer 2

you need to take it to a place that works on engines for that, they can Do a Dyno for you