leakdown vs compression

[fitchnpolo]

What's the difference between a leakdown tester and a compression tester? which is superior? about how much do they cost?

[AustinGT]

Let mess if I can explain this. A compression test tests to make sure that there are no "leaks" in the cumbustion chamber. Causes of such leaks may include a bad head gasket or valves that don't seat right. If you have bad compression alot of places will do a leakdown tet which basically means that thye pour a small amount of engine oil in the cumbustion chamber to see if the compression comes back up. If it comes back up then you might have bad valve stem seals or piston rings.

Hope this helped,
AustinGt

[gothemperf]

A compression tester measures maximum compression during the compression stroke, and informs you if you have a sealing problem in any or all of the cylinders. A leak down tester determines where specifically you are losing compression. You pressurize the cylinder at TDC(same pressure for all cylinders) and then listen for leaks(at the tail pipe, intake manifold, crank case(oil cap), remove the radiator cap to see if air is bubbling out, etc) which tells you what you need to fix before you start taking everything apart.

[HONDA GHANDI]

wrong.

A compression test gauges teh overall health of an engine by measuring how much compression it makes on a compression stroke on its own cranking power. If that number is abnormally low for some reason you would hook up a leak down test tool and artificially pump air into a cylinder to measure its exact % of leakage and also listen for escaping air to verify what and where the leak is going. For example if your engine had a misfire on #1 cylinder and compression is at 80psi when the rest of the engine is at 160 you would either A) tear down teh motor and inspect it for damage or B) move on to leakdown. Now the leakdown test can tell you exactly where teh leak is occuring by listening for escaping air pumped into the cylinder by the tester. If you hear air up in the intake manifold you most likely have a burned or bent intake valve. If its leaking and hissing throughthe exhaust you most likely have a burned or bent exhaust valve. Now you will always be able to hear a little air escaping through the crankcase because rings are not total sealingbutif there is a LOT of hissing or air escaping into the case or heard at the oil filler hole you most likely have a piston ring failure or worse yet a piston failure. If air bubbles are detected in the radiator you most likely have a headgasket failure or worst case, a cracked head or block. So in answer to your question, a compression test can give you an overall picture of the health of your block and a leakdown will give you more specifics on certain areas that cannot be seen by the compression test.

[HONDA GHANDI]

not wrong to gothem, I took to long to type my description so I got owned.

[cherrybombcivic]

hey fitchnpolo, is that a 3ds max animation for your avatar?

[servion]

Anyone know of a place locally (colorado springs, or evern denver) where a leakdown tester can be bought?

[HONDA GHANDI]

snap-on, mac, matco, toolzone, And I think I saw one at pep boys once. Also there are a few used snap on ones at pawn shops all the time too.