How can the engine head gasket be tested for a leak?

What is the proper way to test an engine head gasket for a leak for a home handyman?

If the engine suffers a loss or low level of coolant it is critical to shut the car off immediately and not attempt to drive the car under any circumstances. If the coolant starts to bubble/steam, shut the car off. After five minutes, crank/start the engine for a few seconds (to relieve stress on stressed piston rings), and then turn off immediately. Tow the car home.

Fix the coolant problem first.

Warning - do not attempt to test engine operation with plain water instead of a proper antifreeze mix. Antifreeze not only lowers freezing point of water, it also raises its boiling point.

Test for compression first with a gauge. If compression is OK according to Haynes manual, it is suggested to test the head gasket for a leak further. One cheap but somewhat misleading way is with a special liquid that will change color if exhaust gases are detected in the engine coolant. While this is a relatively cheap method used by some mechanics, it does not distinguish between a tiny and a dangerous leak. Even good cars are known to fail this test.

If the engine was shut off immediately, cranked for a few seconds afterwards to relieve stress, was never driven before coolant was replenished, and compression is ok, a home mechanic can test drive the car. It is possible that while compression would be good, that a leak nevertheless would exist from the cylinder to the coolant lines. In this case, you will see a steady drop in engine coolant level (it will enter either the cylinder and burn, or enter the oil passages, and make oil white sludge). If engine coolant level is not dropping, compression is ok, and engine oil is clear, then you were very lucky.

No luck? Thinking of replacing the head gasket due to limited funds, but never done it before? Contact me for tips.

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Page last modified 12-Apr-12 21:58:26 EDT
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