The Stovebolt Site Forums The Shop Area The Tool Chest Compression testing.

For the really serious, a differential cylinder pressure testing tool can be invaluable. This device, properly used, allows you to very accuratly diagnose valve or ring problems. I'm still surprised by the number of pro mechanics who do not use them or think that they're not worth the money. Peruse one of the many sites dealing with the care and use of one to find out the story. I wouldn't be without mine as a basic requirement for engine condition determination. Plus it looks really cool in use. Only thing is, when you read where it is possible to get hurt using one, let me assure you that THEY ARE NOT KIDDING.
Regards,
Ken Beckman

Handier than toothpicks at a sushi bar, a compression tester (most have included fuel pump reading as well), vacuum gauge, VOA meter, are invaluable tools for any mechanic. Add a remote starter and you're a one-man diagnostic center. Without them it is (expensive) trial and error.

Not that kind of compression tester, Laurence.
The kind you use on aircraft engines. Commonly called a leak down tester.
Regards,
Ken

As in cored sparkplug attached to compressed air?

www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/index.html -

Better article.

www.xs11.com/tips/misc/misc3.shtml -

Great article. I've always used the regulator at the compressor (or pinched the hose) to regulate the volume pressue on my home-grown tester. Having it closer to the working end is the better idea. However, I've only used the rig when shorting out, stethescope, or tailpipe flutter is not definitive. You are correct - it is an excellent method of determining internal cylinder condition short of a tear-down.