Compression testing is a crude form of leak down testing which also includes effects due to compression ratio valve timing cranking speed and other factors. A leak down test can tell you quite a bit more about an engines mechanical health than a compression test can.
Leak Down Tester Wikipedia
What is a leakdown test. A leak down test also includes putting a pressure gauge into each cylinder in the engine though in this instance it is a leak down test device that is inserted with a display that incorporates two separate dials or displays. This is done by inserting compressed air around 100 psi into the cylinder at tdc and then measuring how much is lost. As we outlined above a compression test is all about measuring the pressure that the engine can generate itself. A leak down test is one way a mechanic can find whether an engine has an internal problem instead of something external like a bad spark plug. Leak down is the percentage of compression that is lost by the engine and every engine has some. They both test the sealing ability of the combustion chamber but the leak down can tell you how much is leaking and where its going.
This procedure is different and usually more accurate than a compression test which just measures the pressure inside a cylinder. Leakdown test the leakdown test measures how well the cylinder is sealing. A leak down tester is a measuring instrument used to determine the condition of internal combustion engines by introducing compressed air into the cylinder and measuring the rate at which it leaks out. A leak down test is a compression test in reverse. The leak down test measures pressure loss inside a cylinder. Browse recommended tools supplies for this build.
Unlike a compression test a leak down tester has two gauges and requires a compressed air source. Like a compression test a leak down test is accomplished by replacing a spark plug with the tester hose.
Gallery of What Is A Leakdown Test
