Snap-on Leak Down Tester - Dual Gauge
 

First time user for this little device. Did everything according to instructions. But there is problem. I can hear a small amount of air leaking past the rings when the leak down gauge is showing an improbable 0% leakage. Anybody else have this problem?

Re: Snap-on Leak Down Tester - Dual Gauge
 

My bad Bruce I have the single gauge snap on leak down tester . I have problems getting consistent readings on same cylinder.

Re: Snap-on Leak Down Tester - Dual Gauge
 

Thanks Glenn. Kind of surprising that Snap-on would have their name on a bad piece of equipment.

Re: Snap-on Leak Down Tester - Dual Gauge
 

I've had mine about 30 years, it works fine. Realize it is not a medical grade instrument, nor is it a certified instrument. But then, it doesn't cost that much, either.

It is very sensitive to inlet air pressure. Mine does not like anything over 100 psi.

Re: Snap-on Leak Down Tester - Dual Gauge
 

Bruce, I don't don't think those regulator type gauges work real accurately with little or no air going through them.
Try loosening up the plug till it reads and then back it back down..
You probably have about 2 % :-)

Re: Snap-on Leak Down Tester - Dual Gauge
 

I still have an old Sun percentage of leakage tester, one gauge. I have never seen one of those cheaper two gauge units I thought was correct. No two appear to give the same numbers. Usually low. I have seen 2% on those when you can hear air out of the crank case breather. My Sun would show 6% to 8% on the same cylinder. Only thing that would show 2% on mine would be some Total Seal gapless rings. Also had one built into one of my big Sun engine Analyzers, both read the same. Be worth it if you could find one.

Re: Snap-on Leak Down Tester - Dual Gauge
 

I have had this unit for several years and just got around to using it the other day. I don't think it was cheap. After calls to several different Snap-on numbers and 18 prompts later I did get some info. Nothing really new, there is a .040 orifice that meters the air from the pressure side. The air passes by the leak down gauge and then to the spark plug hole. Once the cylinder is full, the leak down gauge can read the pressure. So according to these folks you can get close to a zero leakage with a .019 top ring gap. Also, I made the mistake of not using the long thread adaptor. So live and learn.

Re: Snap-on Leak Down Tester - Dual Gauge
 

The best I've seen with my stuff is around 4% or so. Knowing how little blow by there is on the dyno, I'm okay with that. A leak down test is a diagnostic test to locate a problem if something is wrong. Given that it is a static test, you're just finding where the leak is, and what the likely component is. I only leak an engine to see what is wrong with it in most cases. I suppose you could leak an engine fresh off the dyno, establish a baseline, then use that to see what the ring seal is after a given number of passes. The problem is accurately duplicating the conditions.

Re: Snap-on Leak Down Tester - Dual Gauge
 

Actually meant to say to loosen the hose in the plug hole, just to see a reading.
Suggestion still applies.