Blown Head Gasket Diagnosis

The head gasket forms a seal between the engine block and the cylinder head, and it must keep the engine oil, cooling fluid and combustion gases separate. Symptoms of a blown head gasket generally involve the undesired mixing of these fluids.

Oil and Coolant Leaks

Examine the upper part of the engine for fluid leaks. A leaking head gasket will often reveal itself through oil or coolant leaks around the upper part of the engine where the cylinder head and the engine block meet.

Engine Oil Symptoms

A light beige froth or foam in the engine oil is a sign that cooling fluid is leaking through the head gasket and mixing with the oil. This foam will usually be visible with the oil on the end of the dipstick.

Cooling Fluid Symptoms

If engine oil is leaking through the head gasket and mixing with the cooling fluid, you will see an oily scum floating on the surface of the cooling fluid in the radiator, and the cooling fluid will have a brown, oily appearance.

Engine Exhaust Symptoms

A blueish smoke in the engine exhaust is a sign that oil is leaking into the engine cylinders. A white smoke indicates that cooling fluid is leaking into the cylinders.

References

• How to Change a Head Gasket: Signs of a Blown Head Gasket
• The MGF Gallery: How do I diagnose a head gasket failure?
• Free Online Auto Repair: Head Gasket Repair -- Troubleshooting & Repair