aggie Posted August 26, 2023 Report Share Posted August 26, 2023 What is the correct procedure for doing a compression test please ? Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 26, 2023 Report Share Posted August 26, 2023 best on a hot engine so it turns over easy all plugs out open throttles fit gauge and crank to get the highest reading Pete Link to comment Share on other sites More sharing options...
JohnD Posted August 26, 2023 Report Share Posted August 26, 2023 (edited) Have you done a search here or elsewhere? This is such an old chestnut, but everyone has to learn! Remember: 1/ A compression gauge is NOT a precision instrument. Never compare your readings with someone else's, unless done on the same day with the same gauge! 2/ The gauge is most useful to compare cylinders along the block. Ideally they should all be the same, but +/- 5psi is acceptable. Procedure (have pen and paper to hand!) A/ Warm up the engine to operating temp. B/ Remove ALL the spark plugs C/ Use wire or some other means to hold the throttle WIDE OPEN. D/ Install the gauge into No.1. Tighten it! E/ Turn the engine on the starter until you get a constant reading on the gauge. This may take five or six turns. F/ Note the reading. G/ Repeat for the other cylinders H/ Then do it again. This takes practice and at least two runs along the block will be a start. 10,000 hours not required! If you have any cylinders that are significantly low, then tip a teaspoonful of engine oil into that cylinder, turn the engine over once and repeat the compression test. If pressure reading does not increase then there is a valve problem, and not bore wear or piston ring failure. Good luck! John Edited August 26, 2023 by JohnD Link to comment Share on other sites More sharing options...
aggie Posted August 26, 2023 Author Report Share Posted August 26, 2023 Thanks to both of you, at least I'm getting it from those who know. Now I do also. Link to comment Share on other sites More sharing options...
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