How do you read a leak down test?

If you can hear a hissing sound coming from the valve cover breather hole or from the dipstick tube, then the air is escaping past the rings. If you hear that same hissing sound at the throttle blades and, then the pressure is leaking past the intake valve.

What is acceptable on a leak down test?

Leak-down readings of up to 20% are usually acceptable. Leakages over 20% generally indicate internal repairs are required. Racing engines would be in the 1-10% range for top performance, although this number can vary. Ideally, a baseline number should be taken on a fresh engine and recorded.

What is the best engine compression tester?

The Best Compression Tester INNOVA 3612 Compression Tester. The INNOVA 3612 is popular for several reasons. BlueDriver Compression Tester Kit. The BlueDriver Compression Tester Kit is a high-quality tool set – and it’s designed to be just as suitable for professional mechanics as it is for Orion Motor Tech Compression Tester.

What does a leak down test show?

A leak down test will tell you where you’re losing your compression. Blown head gaskets will present as either air bubbles in the coolant or a hissing sound. The sound of air hissing out of the oil filler, dipstick tube, or PCV valve indicates worn piston rings, a situation informally known as ” blowby .”.

What is cylinder compression tester?

A: Engine compression testers measure cylinder compression and most of them are sold in a complete set with universal adapters for standard and small spark plug threads. Each compression tester comes with a hose that you need to screw into the spark plug hole that belongs to each individual cylinder.

What is engine leak down?

Leak down is the percentage of compression that is lost by the engine, and every engine has some. Like a compression test, a leak down test is accomplished by replacing a spark plug with the tester hose. Unlike a compression test, a leak down tester has two gauges and requires a compressed air source.