What is a head gasket?
A head gasket is a gasket that sits between the engine block and cylinder head(s) in an internal combustion engine.
Its purpose is to seal the cylinders to ensure maximum compression and avoid leakage of coolant or engine oil into the cylinders; as such, it is the most critical sealing application in any engine, and, as part of the combustion chamber, it shares the same strength requirements as other combustion chamber components.
Types of head gaskets:
- Multi-Layer Steel (MLS) – Most modern head engines are produced with MLS gaskets.
- Solid copper – a solid sheet of copper,
- Composite – an older technology. Typically these are made from asbestos or graphite but are more prone to blowouts than newer gaskets.
- Elastomeric – a gasket type used by Rover on their K Series engines. It utilised a steel core plate with moulded in place silicone rubber beads to seal oil and coolant passages.
The cost of a replacement gasket is usually not great, but the price of total repair is considerably high. This is because the procedure of removing/replacing an engine head is very time consuming – around 75% of cost will be labour.
Furthermore, untreated blown gaskets usually seriously damage the engine, then requiring even more expensive work.
Signs that you are dealing with a blown gasket:
- Coolant leaking externally from below the exhaust manifold.
- White smoke from the exhaust pipe.
- Bubbles in the radiator or coolant overflow tank.
- Overheating engine.
- White milky oil.
- Fouled spark plugs.
- Low cooling system integrity.
What causes a head gasket to blow?
The main cause for a blown or damaged head gasket is extreme engine temperature. High engine temperatures are often caused by a coolant leak or just not having enough coolant in the radiator.
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