you should see 135-185psi, but the fact that they are even is a good sign. the fact that they are low could be the gauge or user. was the test done with the engine cold or warm. warm should bring the numbers up. put a teaspoon of oil in the cylinder and try again. if the psi comes up, then the rings are worn. a leak down test is when you use a controlled amount of air pressure with the piston at TDC on the ignition stroke. you read how much air escapes from the cylinder. 25% or more will require some repair. with the cylinder pumped up to pressure, if the air leaks out of the intake manifold then a intake valve or valves are not seating. same thing with the exhaust, air out the tailpipe = exhaust valve. if the air escapes form the dipstick, then the rings are leaking. so you can see haw a test like this is more important then a compression test. a compression test only measures the engine's ability to seal at low rpms. once a engine is spinning 6000rpms, there is a valve open or opening 100 times per second, so a good low speed compression is less important. |