How to Diagnose a Blown Head Gasket

The head gasket on your vehicle seals the head to the engine block. It also seals out the engine coolant that is circulating through cooling channels built into the casting of the block. When the head gasket fails, you'll lose compression in the engine. But before you replace anything, you need to know how to diagnose a blown head gasket. Fortunately, this is extremely simple.

Difficulty: Easy

Instructions

1. Start the engine. You must check for a blown head gasket rather quickly since running an engine for very long with a blown head gasket can cause catastrophic failure of the engine. Diagnosing the problem normally requires running the engine only for a minute or two.

2. Look for white smoke coming out of the tail pipe. White "smoke" is actually steam. The steam is caused by coolant leaking into the engine cylinders and being heated to the point that the water turns into steam.

3. Open the hood and check for steam coming from the engine block. A blown head gasket is almost unmistakable, as it is the only real problem that causes steam to be emitted from the block. Your engine will also sputter and have a rough time idling with a blown head gasket.

Tips & Warnings

• For specific information about your vehicle's head gasket or diagnosing head gasket problems, consult the particular vehicle's manual (see Resources).

References

• Auto Repair For Dummies; IDG Books Worldwide; 1999

Resources

• Automobile Service Manuals

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