What Is A Head Gasket Leak Down Test?

The cooling system of a car should be maintained in pristine condition and every single component that makes up the cooling system should be taken care of. The head gasket is one of the most common components that can mess up with the cooling system due to breakage and leaks. If problems with the head gasket are not attended to immediately, the cooling system may eventually fail. A leak down test is useful for determining whether rings, valves or head gasket causes leaking. Depending on the test result, you can take necessary action to maintain an optimal cooling system.

The leak down test helps car owners and mechanics to zero in on specific parts of the engine that needs repair and attention. Leak down testing kits can be purchased easily to perform this set. The set comes with a calibrated pressure gauge, pressure regulator and associated adaptors to fit the set into spark plug hole. The condition of the internal combustion engines can be determined by reading the leak down testing results. Even though the leak down testing is similar to compression testing, there are subtle differences.

How does a Leak Down Test work?

Compressed air must be first fed to the gauge to calibrate it to zero as the reference point. Then, an adaptor is inserted into the spark plug hole and a gauge is attached to the other end. Once the gauge is fitted, air will begin to fill the cylinder. The gauge will change its reading indicating the amount of air that flows into the cylinder. Depending on whether the damage is with ring, valves or gasket, air will be leaked from various parts of the engine and as a result, problem areas can be effectively determined. If air comes out of the PCV, it indicates a ring leak and if it comes out of the exhaust, then there is valve leak. Air coming out of the oil filler or dipstick hole indicates problem with the piston. Otherwise, when air leakage is found with the radiator filler cap, it can be said that the head gasket has caused the leakage.

Generally, the leak down test is performed after warming up the engine to bring it to normal operating temperature. This will ensure that the gasket expands and seals the cylinder. Many car owners and mechanics claim that this is the best way to get meaningful results through the leak down testing. However, sometimes, the test can also be performed when the engine is cold because trained car mechanics can easily deduce the results of testing as the readings won’t vary very much.

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Can you do the test by yourself?

Anyone with a leak down test kit can perform these tests without professional help. You have to record the gauge readings and watch out for the air leaks. Every cylinder in the car must be tested this way and if numbers don’t match up, you can run the test again to avoid any confusion. You don’t need to be a full-fledged mechanic to ideally determine which part of the combustion engine needs to be repaired. You can’t however perform all major repairs on your own, but performing the necessary tests will help you to save a lot of money while doing any repair.

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