I just bought a engine compression tester that screws into my spark plug{s} hole{s}. What I am wondering is what PSI#'s I should be getting from each cylinder and are the #'s supposed to all be the same or what? Well if anyone can help me out here and try to explain the procedure and what #'s to expect that would be great. Thanks a lot.

 

usually they come with instructions. What you are looking for is differnetials between cylinders, indicating a problem. If they are all within 10% of the the highest, then they are all wearing evenly. A low compression can indicate ring problems or a valve problem, or even a bad head gasket. Why not look for the instructions.

 

Thanks for the info. I bought the gauge new at pepboys a few hours ago and there are no instruction at all.

 

Please get yourself a repair manual. You can buy these books at any large bookstore or auto parts store. They may be available at your public library.

A compression test is an important basic diagnostic test. It will reveal many mechanical engine problems such as worn or broken piston rings, bad valves, blown head gasket.

See the Chilton repair manual (page 3-58) or the Haynes repair manual (page 2C-7). Haynes is the better of the two books.