Leak Down Test Results


Old 01-25-05, 04:44 PM
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Leak Down Test Results

I recently did a valve grind on a 402 Chevy truck engine, I did not do a leak down test before doing the job but after putting it back together I did a compression test and a leak down test. All cylinders except one were from 130-138 and my number 3 cyl on the right bank was at 125. On the leak down test all cylinders were at 6% except the 3rd cyl on the right bank which was at 22%. The leak seems to be crankcase. The engine has 71K original miles on it, no ridge and cylinders looked great when I had it torn down. Could this indicate a broken ring or? Would this be harmful if I don't fix it. The engine seems to run fine but made a little clicking noise and smoked a bit on the left bank (maybe one of the valve seals is a problem), but I have not even ran it 30 miles since doing the head job.

Thanks for any input.
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Old 01-25-05, 11:55 PM
Join Date: Sep 2004
Posts: 132
First, you need to be sure that all the leaks were done at TDC. This is the area where most wear occurs. Leak test results can also be skewed if the rings are dry at the time of the test.

22% is a fair chunk of change. Might not be a big concern bt if you are running high static compression and/or long ignition leads, any oil entering the cylinder could result in detonation.

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