When doing a leak-down Test How much Pressure

[Rolm]

I want to do a leak-down test on one of the cylinders that have a 30-psi. How much pressure should I pump in the cylinder.

Is this the metod

bring piston up to tdc on compression stroke and then compress the sick piston and then listen, if air comes out of crank case then the rings are shot, if air comes out of exhaust then the exhaust valve is shot, if air comes out of the intake then the intake valve is shot. I hope I can rent a compressor or can I use a propane tank as a pressure device.

[GTP Dad]

You shouldn't need more than 75 to 100 psi to do your test. You can easily do that with a compressed air tank since it won't take much volume. Actually if you have a burnt valve you will hear the leak immediatly and probably won't build pressure anyway. Leakdown for rings will take a little more time and air.

[Rolm]

Originally Posted by GTP Dad

You shouldn't need more than 75 to 100 psi to do your test. You can easily do that with a compressed air tank since it won't take much volume. Actually if you have a burnt valve you will hear the leak immediatly and probably won't build pressure anyway. Leakdown for rings will take a little more time and air.

Thank-you for the info, I will try what you suggested. I also found the following link. Great info if you are diagnosing an engine.

http://www.carcraft.com/techarticles...ter/index.html

[Rolm]

I used good old fashiond tire pressure as an air source and it worked great unfortunatly for me it was the piston rings that were shot. I am know looking for a good used engine.