Head gaskets are designed to seal the cylinders' firing pressure and to prevent coolant and engine oil from leaking into the cylinders as well as to the outside.Checked 2026-08-12
Head gasket
The seal between the engine block and cylinder head that keeps combustion, coolant and oil apart.
Also called: blown head gasket · cylinder head gasket
What it means
Definition
The head gasket sits between the two main castings at the top of the engine — the block and the cylinder head. Fel-Pro, an OE gasket maker, states that head gaskets are designed to seal the cylinders' firing pressure and to prevent coolant and engine oil from leaking into the cylinders as well as to the outside. Because it lies between bolted castings, replacing it means removing the cylinder head.
Why a buyer cares
What it changes
It names a specific, identifiable failure rather than a vague engine complaint, and the repair reaches into the top of the engine.
In practice
Where you meet it
On estimates, inspection reports and seller disclosures, usually alongside a coolant or oil-mixing symptom.
Two things that look alike
Not the same as
The cylinder head is the casting; the gasket is the seal beneath it.
Read next
Related terms
Where this comes from