A head gasket is a gasket that goes between the engine block and cylinder head(s) in the engine of your car.
It is there to seal the cylinders in order to ensure maximum compression and avoid leaks of coolant or engine oil into the cylinders. Because of this, it is the most critical seal in any engine.
The typical car engine uses three circuits of working fluids:
1. Combustible mixture (air/fuel)
2. Water based coolant, usually with glycol mixed
3. Motor oil to lubricate
All three are vital and must never be allowed to intermix. Besides sealing the cylinder, the head gasket also seals water and oil conduits between the head and block. Any contact between them will cause engine failure, or significant problems like burning oil (smoke from the exhaust). Blue exhaust smoke may be indicative of oil burning. White exhaust smoke is an indicator of coolant burning, another sign of head gasket wear.
Occasionally, the compression inside the cylinder will cause a leak to form in the gasket and the gasket will need to be replaced. Otherwise, severe damage can take place, known as a “blown” head gasket.
Photo: © 2006 Lewis Collard