leak down test

[JJB]

I wanted to get some info about a leak down test . I have a 2000 175 johnson Ob two stroke . When I was doing the leak down on one cyl , If I removed a plug from any other cyl during the test I could hear air comming out of it as soon as I turn on the air pressure , is this normal for that kind of test . The cyl that was being tested was at TDC with a cyl hold tool installed to keep piston from moving during test.
Thanks for the input JJB

 

[R.Johnson]

Re: leak down test

On a leak test you will hear air rushing out. You can't put in 100#, and exspect the cylinder to hold 100#. The ring gap alone won't allow that. Do you have a true leak-down tester with 2 guages', and a regulator?

 

[JJB]

Re: leak down test

Yes I do , it's the one from harbor frieght with gagues and reg . What pressure and how long should it hold it for ? what is the acceptable % of leakdown at what psi ? Thanks for the input . JJB

 

[R.Johnson]

Re: leak down test

With the air flowing, the loss, or difference not more then 10%. When you shut off the air flow, the pressure will drop in a matter of seconds', again the ring gap. For easy figureing, I use a 100# inlet pressure.