Cylinder Head Gaskets
The cylinder head gasket seals the joint between the engine block and the cylinder head, containing combustion pressure while keeping oil and coolant passages separate.
What it does
It must hold combustion pressure in each cylinder while sealing coolant and oil galleries that pass between block and head, through constant heat cycling and expansion.
Signs a head gasket is failing
- White sweet-smelling exhaust smoke
- Coolant loss with no external leak
- Oil that has turned milky or a mayonnaise deposit under the oil cap
- Bubbling in the expansion tank with the engine running
- Overheating that returns after the cooling system is repaired
When to replace them
Not scheduled. Replaced after failure, which is almost always a consequence of overheating or a distorted mating face.
What to confirm before ordering
Have these ready and the counter can usually confirm the part in under a minute.
- Engine code from the block
- Gasket thickness or grade, where the manufacturer supplies several
- That the head has been checked for flatness and skimmed if needed
- Whether head bolts are torque-to-yield and therefore single-use
Cylinder Head Gaskets by vehicle
Pick your vehicle for the years and engines covered, and what is specific to that application.
Cylinder Head Gaskets questions
What causes a head gasket to fail?
Overheating is the overwhelming cause. It distorts the head, which breaks the seal. Fitting a new gasket without finding out why the engine overheated is how the same failure happens again.
Does the head need skimming when the gasket is replaced?
Check it every time. Since most failures follow an overheat, and an overheat is what warps the head, a flatness check is the difference between a repair that lasts and one that does not.
Do head bolts need to be replaced?
On most modern engines, yes. Torque-to-yield bolts are designed to stretch permanently as they are tightened and cannot be reliably reused.