Leak down test

[Jason]

I used my neighbors leak down tester on my old 95hp sitting in the garage. I did it with the engine cold so the numbers should be a little better with the engine warmed up. Cranked it up to 100psi. All cylinders leaked down to 90 psi. So 10%. My question is, what is ok?

I am going to do the 150 this weekend. We'll see how that compares.

[wexrocks]

I would say that if you got 100psi evenly across the cylinders cold with a 95hp, you are in REAL good shape.

If the 150 is a Merc, I'd look for 120psi+ cold to be in good shape. Mercs run higher compression than Johnson/Evinrudes. Leak down would be more accurate with a warm motor, but an even 90% cold is real good. I'd buy a motor with those numbers if I were looking.

[Jason]

The compression test on the 150 merc varies from 85psi to 150 using three different gauges. So no idea what it really is! At least all cylinders are consistent. When I do the leak down I hope to learn more.