For testing the internal condition of engines , Mechanics have long relied on Compression Testers but there's a much better tool called a " Leak Down Tester " - what it does is puts compressed air into the cylinder via the spark plug or injector hole and then a gauge tells you the percentage of compression that's leaking out . in this way , even a low compression engine can accurately be tested to see if it's good or worn out . A new engine would be under 10 % , a good used engine would be 20 % or less . So , I tried one of these tools on my 1959 Metropolitan Nash , it runs Tip Top & doesn't smoke but it spits a little bit of oil out the breather tube to the tune of a quart of engine oil every 250 miles or so . Results : one cylinder had 32 % (bad) two cylinders had 40 % (worse) and one cylinder had 67 % leakage ! this engine starts instantly hot or cold and gets good fuel milage and makes plenty of power , I had a suspicion the rings were weak or bad and this is the proof . I'd like to use this tool on a Diesel or StoveBolt engine just to see how good or bad it is . -Nate
Leak down tester Nate Can i ask you to take a picture of the tool.Do you connect it with an air compressor/adapter?How much pressure (PSI/LBS) does the tool need to give a more accurate diagnose? Martinius.
Air Requirements Well ; standard shop supply is 150 PSI @ unlimited volume , I don't know the tools requirements but I'd think the Snap - On Tool catalog would give you this info plus a good picture... In due time I'll see if I can rustle up a picture .
Tester, Cylinder Leakage Hey, Nate Is this the product where talking about ? http://buy1.snapon.com/products/diagnostics/eepv309a.asp Martinius
Leak Down Tool THis is the same Tool we use today to test the health of an engine in Airplanes, well Piston Powered planes atleast. And yes Snap on Mac aircaraft tool and i think aircraftspruce all sell them. two gauges witha regulator mounted on a manifold with an orifice in between apply 80 PSI to teh input side of the tool and see what the output side reads the F.A.A> requires the leak to be no more than 20% so a cylinder that reads59PSI or less is failed and has to be replaced. though at this I have failed cylinders for leaks that are less than this due to audible leaking past teh exhaust or intake valve, what is being looked for in this test is leakage past the rings, if the leakage is past the valves it is only goign to get worse and more than likely sooner than the next time an aircraft owner has to bring the plane in for his annual inspection (I have seen it happen in 5 hours burna whole or the edge right off the valve). Also this test is done with teh engine HOT 180 degree F. oil temp if the engine is cooled down the tolerances are way off and it will leak like a sieve. Bill
