Leak down test

[perucho]

I have a BP on a stand and want to do a leak down test to see if I should open it or not before doing the swap. Which way does the crankshaft is supposed to rotate? Does it matter which way I rotate it to get the pistons to TDC?

[wybnrml]

I think it turns clockwise.

[Levitan]

Yes, clockwise.

[eurotiva]

Same direction the wheels would turn if it were in the car.

[perucho]

Great, thanks guys!

[FestYboy]

you MUST hold the crank still when during the test, or you could hurt yourself. use a breaker bar.

[perucho]

Did a leak down test on the engine yesterday. Since the engine is on a stand, the test was done with the engine cold but the numbers are bad enough that it doesn't matter if it was warm or cold LOL.

cyl #1: 75% through exhaust and rings
cyl #2: 53% through rings and exhaust
cyl #3: 80% through exhaust and rings
cyl #4: 40% through rings

I had a breaker bar to hold the crank but didn't need it. The pressure used on a leak down is fairly low compared to the numbers you get on a compression test.

Sucks but I'm definitely going to have to open the engine. I was hoping that the HLAs were not allowing the valves to fully close but I'll feel better if I do a valve and ring job at least.

[FestYboy]

i usually test with 100 psi in the cyl so that the rings expand and seal. hence the breaker bar.

[perucho]

i usually test with 100 psi in the cyl so that the rings expand and seal. hence the breaker bar.

I didn't think of the rings expanding with pressure. The gauge I have is from Harbor Freight and doesn't allow for changing the intake pressure (unless I'm doing it wrong). I had my compressor set at 120 psi but the gauge was only letting the cylinders get about 25 psi.
I connected the dual gauge to the compressor line, set the leakage gauge to 0% leakage using the adjustment knob (the pressure gauge would show approximately 25 psi) and then connected the whole thing to the cylinder with a quick-connect coupler. Those are the instructions for the gauge too, so I don't know if there's a different procedure.
Any ideas? I would like to try it with higher pressure and see if that actually results in lower % leakage.

[FestYboy]

yeah, you're doing it wrong... i have the same unit. once you have it connected, you have to reset the pressure gauge to 100 psi again and then take your reading.

[perucho]

yeah, you're doing it wrong... i have the same unit. once you have it connected, you have to reset the pressure gauge to 100 psi again and then take your reading.

I tried that too but it never gets to 100 psi. It will get to say 50 psi and the % loss will be at 0 but you can still hear air leaking and the compressor's pressure keeps dropping. I also read online that that's not the way it works.
Any other ideas?

[FestYboy]

hmmm odd. what you're looking for is a differential between the first and second gauge. i've nevere had issues w/ mine using it as stated.