# Cylinder leakdown test



## G.MAN (Jul 8, 2012)

*HOW MUCH AIR SHOULD BE PUT INTO THE CYLINDER AND HOW DO I KEEP ENGINE FROM ROTATING WHILE PUTTING AIR IN TO IT.:wave:*


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## paulr44 (Oct 14, 2008)

If you only have 1 gauge on your tester, set the pressure for 100 PSI then do the test. A 10 PSI loss (90 PSI reading) would equate to 10%, 15 PSI as 15% etc.

You can put the engine at TDC and hold the flywheel nut or PTO (clutch, etc.) bolt with a socket and 1/2 breaker bar. NORMALLY, either the clutch bolt or flywheel nut torque in fact should be enough to hold it back even but if it's a problem lay it up a tad BTDC and the desire to rotate will only serve to tighten the nut and stop it from turning.

YOU SHOULD USE 2 PEOPLE to do the test. If you don't have two people, you'll have to figure something out how to hold the engine steady without the risk of being injured because you could only use one hand. USE TWO HANDS to hold it steady please.


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## RKDOC (Jun 20, 2006)

Someone correct me if I am wrong. The way I do a leakdown test, is to attach the gauges. Set the gauges and compressor to 70 lbs. with the air going into the cylinder I pull the starting rope. When the piston reaches TDC the gauge will show no leakdown, and you will not be able to pull the cylinder beyond this point, if the valves and everything are good. If something is bad you will be able to pull the cylinder past TDC without it stopping. If something is bad you will hear the air leaking. Determine where the air is leaking and you have found your problem.


I have found I can do this alone with out a lot of work clamping the flywheel to hold it in place. If this is not correct and giving me inaccurate readings please let me know.


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## paulr44 (Oct 14, 2008)

http://static.summitracing.com/global/images/instructions/sum-900010.pdf


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