Head Gasket Replacement
The head gasket seals the joint between the engine block and cylinder head, keeping combustion pressure, coolant and oil in their own passages. When it fails the three can mix, and driving on can destroy the engine. We confirm the failure with tests first, because overheating can also mimic it.
From AED 2,499Written quote after diagnosis, before work startsConvenience fee applicable · shown on your written quote
- 2-4 days, longer if the head needs machining or parts are on order
- Pickup and delivery from your door
- Convenience fee applicable · shown on your written quote
- Diagnosis free with repair
Signs you need head gasket replacement
- White, sweet-smelling smoke from the exhaust that does not clear when warm
- Milky, mayonnaise-like residue under the oil filler cap or on the dipstick
- Coolant level dropping with no visible leak
- Bubbles in the coolant reservoir, or the reservoir pressurised and hard when cold
- Overheating that returns soon after a repair
- Misfire on one or two neighbouring cylinders, especially at start-up
What usually causes it
Previous overheating
Aluminium heads warp when they get very hot. The surface no longer meets the block flat, so the gasket stops sealing. Most gasket failures follow an overheating event.
Age and thermal cycling
Constant heating and cooling make the head and block expand and contract, gradually fatiguing the gasket's multi-layer steel structure and letting combustion gas push through.
Detonation and high boost
Knock or excess cylinder pressure on turbo engines can blow the gasket between cylinders or into a coolant passage.
Loose or stretched head bolts
Bolts that lost clamp load, or were reused when they should have been replaced, let the head lift fractionally under load. Many engines use torque-to-yield bolts that cannot be refitted.
How we do head gasket replacement
- 1
Prove the diagnosis
A chemical block test detects exhaust gas in the coolant, and compression and leak-down tests show which cylinder is leaking and where the air escapes.
- 2
Strip and inspect the head
We remove the head, check the block and head faces with a straightedge for warping, and crack-test the head. If it is out of tolerance it goes to a machine shop to be resurfaced.
- 3
Rebuild with new hardware
A new multi-layer gasket, new head bolts, fresh seals and a new thermostat or hoses where worn go on. Bolts are tightened in the stated stages and angle.
- 4
Refill and verify
Coolant is replaced, the system bled and the oil changed because it was contaminated. After a heat cycle the car is road tested and the block test repeated.
In Dubai, Sharjah and Ajman
Because overheating is the usual trigger, heat is the local factor: a cooling system that was only marginal in a mild climate becomes a head gasket problem at 45 degrees. We always inspect the radiator, fans and water pump during a gasket job so the same failure does not repeat in August.
Questions about head gasket replacement
Is it worth repairing, or should I replace the engine?
If the block and head are intact, replacing the gasket is much cheaper than an engine swap. We tell you honestly after the teardown if the damage has gone beyond a reseal.
Can sealant additives fix a head gasket?
They sometimes slow a minor leak for a short time but they can also clog heater cores and radiator passages. We do not use them as a repair.
Why does the head need machining?
Even a slightly warped head will not seal a new gasket. Measuring the flatness and resurfacing it, if necessary, is what makes the repair last.
How soon after the repair can I drive normally?
Immediately, but we recommend rechecking coolant level and oil after the first few days. The oil should be changed again soon if the engine had coolant in it.
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