Leak Down Test

[Guest]

Ok this might be a stupid question but I did a compression test on my 83 gs1100 motor and was getting about 145psi in each cylinder. So today I did a leak down test and was only getting marginal results? Now I have done tests in the past and have found it hard to turn over the motor to TDC with the air in the cylinder but it was quite easy to do with this engine. Does this make sense to anyone? I thought if you have good compression then you would have a good leak down test as well.

Thanks
Paul

[psyguy]

145psi accross all cylinders is an excellent result.
how difficult or easy the engine turns on the crank nut depends largely on what lenght spanner arm you use but it can be done relatively easily i'd say .
a leak down test tipically produces results equal or better than a dry test, provided it's done under the same conditions (warm engine, WOT).

[chef1366]

Did you have the spark plugs in?

[pauly]

No I had all the spark plugs out. I know on some engines in the past it was really hard to turn the motor to TDC when doing a leak down test. This one was really easy.

[chef1366]

I need to read before posting.

[pauly]

Also to add my other motor has a low compression reading on cylinder 3 of about 100psi. The rest were around the 135 mark. When I did the leak down on that motor I could barely get it to TDC with the pressure it was holding. The results were about 4% leakdown. This was the case for every cylinder. Maybe I have a bad compression guage? This is really a mystery.
Thanks for all your help on this by the way.