89gta383

iTrader: (5)

Trying to diagnose why I am down on power from this thread:

https://www.thirdgen.org/forums/alte...-low-dyno.html

I'm trying to do the leakdown test with the dual guage set-up, first guage is pressure in, and second guage is leakdown %. None of the cylinders will take 100 psi. When I turn the regulator to 100 psi, the second guage reads before the 0 (using the same scale it would be -15%).

The passenger side cylinders read 5% when I use 70 psi in pressure, but when I use 70 psi on the driver's side, nothing registers on the guage(still at -15%). I hear air from the timing chain area on when testing either side. The front of the motor is currently apart after I degreed the cam, so I know I'm at TDC on the degree wheel. I even tried before and after TDC 5-10 degrees.

I'm using a harbor freight tester, and returned the first one thinking it was defective, but got the same results with this one. Compression test was 200-210 on all cylinders.

Any ideas?

ede

sounds like either you're not using the gauge right or you have leakage past the rings or valves, if you got 200psi and all holes are within 10% on the compression test i wouldn't worry about leaking it.

89gta383

iTrader: (5)

I should be able to put 100 psi through the regulator guage right? The passenger side cylinders will take 70 psi and give me a reading, but the driver's side will only take 10 psi before something comes up on the leakage
% guage. I don't know what else could be wrong besides the tester being bad.

Vader

Make sure the cylinder being tested is at TDC, and the valves are fully closed. It's fairly simple.

89gta383

iTrader: (5)

Tried the same tester on a different car(formula) and got the same result, the leakage guage does nothing.

Tried turning the regulator **** to 100psi then attaching the hose and the regulator guage drops to 93psi, but the leakdown % guage still does nothing.

Is this another way to test?

I'll buy a different tester from napa in the morning to see if it is the tester.

CamarosRUS

Searching leakdowns and came across this. The Harbor Freight leakdown tool got me since I have one.


Did you ever find out if it was the tool or what? I'm very curious.

CamarosRUS

To anyone searching...

The Harbor Freight things are probably just junk. I had to remove the second gauge (% leakdown) and replace it with a normal compression test gauge and everything then worked fine and it is more precise.

My Harbor Freight second gauge (% leakdown gauge) was stuck on 40% when nothing was attached to it and when air pressure was applied it just bottomed out and pegged the needle...Junk.