Stethoscope leakdown testing

[Guest]

I had a nice talk with a mechanic today who logically stepped me through a cylinder by cylinder leakdown test.

Nothing measurable but by ear.
It makes sense. If you take all cylinders and pull all plugs except one. If you then rotate the crank so the piston goes through all 4 cycles then you can listen at the exhaust and the intake and at the oil filler hole for the sound of gas escaping.

Damn sharp stuff and a lot more usefull than a old school compression tester.
Cheaper than a leak down tester too. Its FREE!

[rustybronco]

So at what point while the air is escaping past the valves or rings do you judge the engine good or not? very hard to quantify the amount of leakage by that method don't you think?

[JEEPRUSTY]

So at what point while the air is escaping past the valves or rings do you judge the engine good or not? very hard to quantify the amount of leakage by that method don't you think?

No but if it is producing a leak from one specific location you can judge bent valves vs. piston ring blowby.

All pretty cool. He told me how to easily take an air-tool chuck and make a poor mans compressor\spark plug.

[Texasgs]

That is all good, and it is a good indicator. But a leakdown tester measures in percentage of leakage, and there are established good and bad numbers. All engines are going to have some piston leakage. The catch is you can precisely tell if there are wear problems inside the engine. Doing it by ear you can only guess.

[trippivot]

HISSSS might ba a valve might be muh ear.

It's a JUNK YARD TEST! basicly you can hear a major problem not a slight one..


wet/ dry comprression test will tell you valves or piston rings..

a dual gauge leakdown test will give you the best information you can have for the sealing integrity of a internal combustion engine.