No... I was onlly doing the test to make sure the motor was still in good condition after being boosted for about a year.. I wanted to make sure the rings etc were ok before I did a HG job, becuase if the rings were bad I would have opted for a low compression rebuild,, but now knowing that the motor is good I will just do a HG.. I know anything under 10% is considered to be strong and every tester can be different but I am fairly comfortable just doing a 300$ HG job now to lower the compression

 

10% leakage is quite high...


something extra you might want to do...

check for cylinder scoring (specifically cyl #4):
you can do this by repeating the test with the piston half way down the cylinder. compare the numbers to the test done w/ the piston at tdc. if leakage is higher when the piston is at the middle of the cylinder, the cylinder is scored.

 

From what I have read, what mostly is important is that all the readings are consistant. And I know testers vary alot from tester to tester... But I will try your test when I get back from visiting my family.. It seems like a logical way to find if there is any scoring.. Thanks for the advice..

 

no, it's important that the readings are consistent and also that leakage is below 10%. i'd do more investigation if you're getting 10% leakage. did you open the oil and rad cap? did you listen for air coming from the valve cover area and exhaust pipe? did you look for bubbles coming from the radiator? also, did you do the test on a cold engine? that'll affect % leakage too.

just curious but what gauge are you using? I bought an OTC tester and it measured around 1 - 2 % leakage on my car.

 

[QUOTE=kstokes,Dec 17 2009, 07:18 PM] You rang?

When doing a leakdown test, being exactly at bottom dead-center really doesn't matter. You're really just looking to see if there is any valve leakage or gross piston ring leakage. As long as the intake and exhaust valves are both closed, the position of the cylinder in the bore doesn't mean much. It's wise to error on the "the piston is moving down" side of things as opposed to "the piston is moving up", to keep the engine from spinning backwards as you apply air pressure (sometimes it'll turn a few degrees.)

Just hook up the test rig, apply as much air pressure as your compressor can provide (100psi is a good number, and makes the percentage of leak very easy to figure out...), check the difference between both sides.

You can easily expect to see 3-4-5% leakage, that's pretty normal. If you're seeing >10%, something's wrong. Moreso, look for any gross variance between individual cylinders. If you see 3%, 4%, 3%, 5%, all is well. If you see 3%, 4%, 3%, 16%,

 

The compressor is definately ok. I am not sure of the sizing exactly but it is fairly large. It has no prob getting up to 100 psi....

The tool that i used is a US general.. It is fairly cheap one of ebay... thought it would work fine tho... And yes I had actually had the valve cover totally off for the test. and the rad cap was off as well.. no bubbles while test was being done... The car was also brought to full running temp before the tests were done..Maybe I will do a quick test on my civic.. I know the motor is still strong.. Maybe I will do a test on it and see what the leakage is to kinda get a compare to see how my tool reads..

I used a auto stethacope to try and find out where the air was leaking to, but could not really find any where.. I did find some sound at my intake maifold tho so my intake valves might be alittle out of spec, but I would bring those to spec when the HG was done...

 

Just remember, it's not getting the compressor up to 100 psi's that is the problem, but how much air at 100 psi you have to use. So as Turbo_slug said, a 2 gallon tank is not enough.

 

It's a 2 HP, 17 gallon compreesor??