964 Leak down #s - Need Method validation?
 

K, before I get all excited with my leak down test #s I need to verify my method. I borrowed a low cost Harbor Fright leak down tester from a friend and follow the instruction and review several online video. All had me crank the pressure to 100 psi on the first gauge while the second gauge should have zeroed in at some point (0%) before connection to any cylinder. Well maybe the tool was busted or gauge not reading properly but I could never get it to move at all. The needle pegged at 100 % leakage every time even without being connected to the cylinder. Anyhow, I was able to keep a steady 100 psi on the first gauge, and then decided to follow the procedure from cylinder #1-6-2-4-5-3. So based on a 100 psi from the gauge (before connecting to cylinder I assume 100 %, then when I connected the tool to each cylinder, I measure the remainder of pressure from that first gauge.
NOW big question,.. is it safe to assume that if connected to a given cylinder I read 93% then I have a 7% leak on that cylinder ???
Please help.

Thanks

Yes, it sounds like you are doing it correctly. Each of these testers is a little different. I have an OTC model with two gauges. Per the instructions I put 110 PSI on the input and then dial in 100 on the second gauge. Then when connected to the cylinder the one that started at 100% goes down to say 95%. That is 5 percent leakage. Read the manual for the Harbor Freight leakdown tester. They have the manuals on their website.

The Harbor Fright tool is a real POS. It does sound like you got results but the accuracy of that tool a VERY suspect. Do someone a favor and toss it in the trash......

Normally the harbor freight leak tester doesn't let you get beyond about 35 psi to zero out the percent leak gage. Many people have posted they had this problem. Try it out by increasing pressure using the pressure regulator until the leak percent zeros out. You will be between 30 and 35 psi.

Yes that sounds about right. When I tried to zero out the second gauge, the first one only red about 35-40 psi.
So I ignored the second one, and cranked up the fist gauge to 100 psi, then hook up to cylinder, and observed pressure drop on first gauge. So if measured 92-93 psi, then I assumed 7-8 % leakage. Can someone confirm if this would be an acceptable method??

Thanks