Compression test vs Leak down test
 

I ran a compression test on my stock A and the range was from 62 to 65 pounds. Then I ran a leak down test and all the cylinders were different with one only registering 18 pounds with 40 applied. Can anyone explain why one test was OK while the other was poor. Thanks for any help.

Re: Compression test vs Leak down test
 

Was the engine held at TDC on compression stroke for each cylinder ?
Where was it leaking from, intake,exhuast,crankcase

Re: Compression test vs Leak down test
 

Try that leakdown test again. Put the cylinder you're testing on TDC compression stoke and put it in high gear and hold the brakes to keep it from turning. then apply 80 lbs of air to that cylinder and see what you have. Listen at the exhaust, intake, oil filler and take the cap off the radiator and look for bubbles.

A compression test will tell you if you have a problem, A leakdown test will tell where the problem is.
Bill

Re: Compression test vs Leak down test
 

agreed 100%

Re: Compression test vs Leak down test
 

I did have the cylinders on TDC but I only used 40 LBS. I could hear the leak coming from the intake. One cylinder held 30 LBS and the worst was only 18 LBS. I guess my intake valves are leaking some but the compression test seemed good.

Re: Compression test vs Leak down test
 

The compression readings are fine. I wouldn't worry about that engine.

40# on the leak test is fine. If you heard the leak on all cylinders from the intake I still don't think I'd worry about it. It does seem as though the engine rolled a bit when the air was applied. Just to be on the safe side I think I'd check the lash.

Re: Compression test vs Leak down test
 

I'll check the lash. Thanks for the help.