I am trying to understand how to use my new leak down testing tool from HarborFreight. I am trying to see if my rings are sealing on my rebuilt motor. I hook everything up and I can hear the air through the oil filler but the gauge reads 0% leakage? I can hear it leaking so I know it is not zero - is the tool broken? (it is HF after all) What is the typical pressure when zeroing out the % leak down gauge? Mine reads 12 psi - seems low but the pressure may be irrelevant when determining leak down?

Thanks!

I don't quite understand your question

do you mean your intake pressure is 12psi?
most of the guages work at 100psi
(I have seen 50psi ones, and then you double your results to figure leakdown)

so the motor needs to be hot
pull the plugs 1 at a time as your doing that cylinder
turn it to tdc for that cylinder before pulling the plug.
(the reason is that if you were to drop a bit of carbon as you pulled the plug, the valves would be closed for that cylinder already and eliminate the chance that the bit that dropped could get under the valve)

incoming air at OVER 100psi
crank the incoming air down below that
(failure to do so can damage the guage)
install guage.
crank air up to 100
see what 2nd dial reads for leakdown numbers

that should do it
oil filler would be rings.
exhaust would be exhaust valves
carbs would be intake valves
brant

Brant - The directions said to apply the pressure and adjust 'til the second gauge says 0%. It was at this point the first gauge is reading 12psi? When I crank the incoming over that the second gaquge is off the scale. Will exchange today and see if it is the operator or the equipment.

The HF leak tester is HORRIBLE! And fragile.

Spend a little money and get a better tester.

Zach

Now you tell me! It is identical to others I've seen on the internet - and $26 vs $80. I am on my second one - let's hope it is better?

Can someone clarify the instructions when adjusting the pressure? Some say adjust to 100 psi while the instructions say adjust so the "% Leakage" gauge reads zero. When I adjust the input pressure to 100 the "% Leakage" scale is off the chart. My problem when I follow the instructions the % leakage stays at zero while the input gauge reads 12psi - even though I can hear the leaking through the oil filler.

I have not tries my second gauge - hopefully it will be better? I will treat it more gently than I did my last one.