Gordo Posted September 18, 2011 Share Posted September 18, 2011 When you have low compression in a cylinder. how do you test to see if its the rings , piston. Or the valves not seating properly. I have herd of a leak down test. How do you do this. With the piston at top dead and compressed air you can hear the air leaking out. Quote Link to comment Share on other sites More sharing options...
luvemfast Posted September 18, 2011 Share Posted September 18, 2011 Do a test, record readings. Squirt some oil in the plug hole before you do another test. Record and compare readings. Theory is, higher reading means the rings are gone. Same reading, valves are leaking. Quote Link to comment Share on other sites More sharing options...
Wayne G Posted September 18, 2011 Share Posted September 18, 2011 Leak down tester is much more accurate however oil and compression test is a good guide. Don't forget that the valves are partially open at top dead centre one of the two times the piston is there so make sure that you are testing it at the time it would spark! There are reasons for low compression other than rings or valves and in some circumstances a small loss is acceptable and may even rectify itself with a decent run especially if the engine has not been worked for sometime. Quote Link to comment Share on other sites More sharing options...
peter mc Posted September 18, 2011 Share Posted September 18, 2011 mmm if the valves are closed and you have air leaking the head has to come off so you can have a better look Quote Link to comment Share on other sites More sharing options...
Gordo Posted September 18, 2011 Author Share Posted September 18, 2011 Thanks guys will try the oil tomorrow, and see how it goes. Regards Gordon. Quote Link to comment Share on other sites More sharing options...
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