Head Gasket Failure: Symptoms, Causes and What Happens Next

What the head gasket does

The head gasket seals the joint between the engine block and the cylinder head. It keeps combustion pressure in the cylinders and keeps oil and coolant in their own separate passages.

When it fails, those things can mix or escape, and the symptoms depend on where the seal has broken down.

Common symptoms

The classic signs are losing coolant with no visible leak, the engine overheating, thick white exhaust smoke with a sweet smell, bubbles in the coolant expansion tank, and a milky or mayonnaise-like residue under the oil filler cap.

You may also notice a rough running engine, misfires, or the heater blowing cold because air has got into the cooling system. Not every symptom appears at once, and some, like residue under the oil cap, can also be caused by lots of short trips in cold weather.

What causes it

Overheating is the most common cause. A coolant leak, a failed water pump, a stuck thermostat or a broken cooling fan can let the engine get hot enough to warp the cylinder head and damage the gasket.

That is why an overheating warning should always be taken seriously. Stopping promptly can be the difference between fixing a hose and replacing a head gasket.

How we confirm it

We do not condemn a head gasket on guesswork. We pressure test the cooling system, carry out a chemical block test for combustion gases in the coolant, and where needed do a compression or leak-down test. That tells us whether the gasket has gone and whether the head needs attention too.

Head gasket repair in Oldbury

If you suspect a head gasket problem, avoid driving the car hot and call us on 0121 544 3736. We will test it properly, explain what we find and give you a clear quote before any work starts at our Oldbury workshop.