Leakdown Test, Need Help!!!
Thread Starter
Le Mans Master
Joined: Jun 2006
Posts: 6,979
Likes: 31
From: Wichita KS
Leakdown Test, Need Help!!!
When doing a leakdown test do you leave the compressor hose on the gauge and set the other gauge to "0" (or set) and see if it bleeds down that way? I hear air escaping from somewhere but I want to say its the piston, the 2nd gauge will not move from "0", also the 1st gauge only has about 25 psi on it shouldnt I have about 80 psi? I have the rockers off so the valves are closed... Please help me out thanks!!
Uneducated autodidact
Joined: Feb 2001
Posts: 5,413
Likes: 253
From: West of the Sabine, Texas
Just bring each cyl to TDC firing, install the tester into the spark plug hole, and pressurize to 100 psi. Read the 2nd gauge on the tester for the results...91psi means 9% leakage, for example. If you have all the rockers off and you can't pressure up, do you have bent valves?
Thread Starter
Le Mans Master
Joined: Jun 2006
Posts: 6,979
Likes: 31
From: Wichita KS
Just bring each cyl to TDC firing, install the tester into the spark plug hole, and pressurize to 100 psi. Read the 2nd gauge on the tester for the results...91psi means 9% leakage, for example. If you have all the rockers off and you can't pressure up, do you have bent valves?
Last edited by Corvette Don; Nov 11, 2008 at 03:52 PM.
Race Director
Joined: Nov 2000
Posts: 10,347
Likes: 673
From: Beverly Hills (Pine Ridge) Florida
You will always have some leakage past the piston ring gaps.
Also listen at the throttle body (for intake valve leakage) and at the exhaust pipes (exhaust valve leakage). These 2 should not leak!
Plasticman
Also listen at the throttle body (for intake valve leakage) and at the exhaust pipes (exhaust valve leakage). These 2 should not leak!
Plasticman
Thread Starter
Le Mans Master
Joined: Jun 2006
Posts: 6,979
Likes: 31
From: Wichita KS
Just bring each cyl to TDC firing, install the tester into the spark plug hole, and pressurize to 100 psi. Read the 2nd gauge on the tester for the results...91psi means 9% leakage, for example. If you have all the rockers off and you can't pressure up, do you have bent valves?
, I really thought I would have at least bent 1 valve with the over rev. Glad all is good.
