If you have leakage you can usaully listen to determine if it is going out the intake exhaust or into the bottom end. The most desirable situation is that all cylinders give the same or close to the same reading.
Checking For Bent Valves Broken Timing Belt Denlors Auto Blog
Compression test for bent valve. A 91 compression ratio cylinder is compressing the air and fuel mixture to about 132 psi at sea level 9x1471323. You can get some feel for the compression by turning the engine over with a ratchet and socket on the crank pulley. As a general rule a compression of 135 psi or better is excellent. The difference you see although not perfect but definitely not your problem. This video covers compression testing which will. This will also cause low compression in that cylinder and a compression test will confirm that.
If you have an engine miss or performance problem dont forget to check for a mechanical problem such as compression loss with the engine. It wont have any compression if it has a bent valve. In the case of bent valves there will be no compression as the air fuel mixture will push back out the intake or exhaust. Furthermore that reading should be above 135 psi. How to perform a compression test ericthecarguy duration. How to check for bent valves after timing belt failure duration.
Even if you are just noticing a general lack of power a compression test can help you rule out some of the more serious possible causes. You should feel each compression pulse. I like to use a leakdown tester for a more accurate way of seeing where i am losing power from. You need to have reasonable compression to do a leakdown test. The same goes for bent or leaking valves. Engine compression atmospheric pressure at sea level is approximately 147 psi.
Similarly a compression of 85 psi or lower is extremely bad.
Gallery of Compression Test For Bent Valve
