So if it is an immediate reading it will stop leaking are once it gets to a certain point. In other words, you put 100 #'s of air into the cylinder and it leaks down to 95 #'s in a few seconds then stops leaking that would give you 5% leakage. Is this correct?

I was thinking that if things weren't sealing 100% they would continually leak down to 0 in a matter of time. Say 95 #'s after 10 seconds, 90 #'s after 2 minutes, etc, etc.

That's what I get for thinking!!!

You hook up an active airline to it. Set the regulator too 100#s and the other dial shows how many pounds the cylinder holds. It doesnt leak down to zero becuase it has air going to it. The term leakdown is kind of misleading. It actually shows how much air passes through the cylinder. Should be done on a warm engine. Hope that explains it better.

I thought you pressurized the cylinder to a prescribed PSI on one gage, shut off the incoming air and then monitored the pressure drop over time with the other gage.
If you have constant air pressure flowing in, how could you measure pressure loss?

Try here. Its a much better explanation.

http://www.goodvibesracing.com/leakd...structions.htm

Nothing stock about that motor

So the left gauge would be putting the regulated air in constantly. But the right gauge would actually be reading the air pressure of the cylinder. So, if your putting 100 lbs in and the cylinder will only hold 95, then you have 5%. Correct?

I was with Iggy. I thought you pressurized it, turned the air off and monitered.

Learn something new everyday!

Be aware that a leakdown tester that you can buy has a metered orifice after the regulator and before the second gauge. This orifice is sized to provide a percentage of leakdown shown that corresponds to a leakdown over time test.

All of the old Clymer motorcycle manuals illustrate doing a leakdown by pressurizing and recording pressure loss over a time period and then computing the percentages. The two-gauge testers mimick this same procedure but shortcut it by giving you a direct reading. Without an orifice, though, the leakdown numbers will be ridiculously low since the regulator can supply a large flow of air before showing a significant drop in pressure.

I'm not sure of the orifice size in these units, but if somebody will take one apart and measure it for us, then we have all the info we need to build a tester that performs exactly like the purchased units.

Orifice size, anybody ??

Orifice size, anybody ??

Keep it clean and stay away from my orifice !