just wondering if i've been doing this all wrong over the years..


i get the motor warm and set cyls to tdc.

when i hook up the gauge to the cylinder i start at 100 psi but it usually drops down to 90 something. if i leave it at that i get readings in the 10-20% range.

now, once the cyl is pressurized if i adjust the psi back up to 100, my leakdown goes down about 10%.


so, do i leave it like the first situation with 100 psi when i hook it up and thats the result, or do i put the psi back up to 100 from 90 something after i hook it to the cylinder...


this particular motor i know to be very healthy, it cranks over 208-210 psi on 9.3:1 static and pulls 23.5" at idle

 

i dont know how you do it but i have a harbor freight leak down tester and all i do is set my compressor to 100 psi
then turn the **** on the tester counterclockwise then slowly turn it clockwise till it says set on the gauge, i dont look at psi

then i plug it in the cylinder and tells me the leakage. and i can crank the pressure a bit higher to see where its coming from

 

well once i connect tester to cylinder the psi drops below 100, which would effectively take the needle off set and put it up toward 10%. set only works as a reference point if there is 100 psi in the cylinder....right?

 

well once its at set and you connect it then it will go to 10% or up
and thats ur cylinder leakage

 

Yes, you need to further turn the **** after the base pressure "sets", i.e. have it at 100psi input pressure once connected.

 

right, thats kinda what i thought once i got into how it really works. i have a little leak from the connection where the gauge hooks to the hose going into the spark plug hole, i can hear it hissing a little