What’s important about getting my head gasket changed and what does it actually do?

A head gasket seals the top half of the engine to the bottom half. Its job is to keep three main functions of the engine separate.

These functions are lubrication of the engine by use of oil, cooling of the engine by coolant/water and compression of the engine in the form of air and fuel.

If any one of these come in contact with the other the engine will fail. The head gasket is the one item they all come in contact with or pass through.

This makes it one of the most important gaskets in the engine, if it fails one of the points below may come in to play.

These points can also be used as a check list to see if you have a possible head gasket failure along with our free ‘Head Gasket Calculator’ which asks a series of questions to assess the likelihood of HGF in your vehicle.

FREE HGF CALCULATOR


All of the issues on this page can be repaired on site by Rough Luck Racing Mobile Mechanics.

Oil leaking to the outside from half way up the engine

This would be rare and nearly impossible without going through a water channel on the inside of the engine.

Possible Damage: Although nearly impossible a loss of oil could be heard by the engine getting louder as metal rubs against its self with no lubrication, Oil loss in any engine can cause major damage.

What to look out for:

  • Excessive use of oil

Oil leaking to the pistons and compression area (Cylinders)

This could be seen by the engine exhaust gases burning with a pale blue smoke, however the rings on the pistons being worn may also cause the same blue smoke.

Possible Damage: This may cause damage to the emissions sensor (lambda) or catalytic convertor. Spark plugs will become caked in a black coke and fail to work in extreme cases. The engine will not pass emissions regulations and becomes harder to start from cold.

What to look out for:

  • Excessive use of oil
  • Blue exhaust smoke when running
  • Harder to start from cold
  • Failed emissions tests
  • General rough running of the car

Oil leaking to water/coolant and coolant/water to oil

This is more common in head gasket failure and can be seen in two ways. When dipping the oil it should be a clear honey colour if it’s new oil or black if the oil is old. In the case of oil leaking or water leaking then the oil will become thick and coffee coloured. Also oil will float on water so check the expansion bottle where you top up with coolant. It may have oil floating on top of the coolant, in extreme cases the coolant which is under pressure may have all disappeared in to the oil, this can be seen on the dip stick as a high oil level.

Possible Damage: This situation is serious for the engine, a lack of coolant and oil will cause major damage very quickly do not drive or run the car.

What to look out for:

  • High oil level
  • Coffee coloured thick oil
  • Oil in coolant/water
  • Low or no coolant

Coolant/water leaking to the cylinders/compression area

This is also a common and major problem as coolant/water can not be compressed. In small amounts water will be seen out of the exhaust as white smoke. Engine gasses may also be seen in coolant and turn it a darker colour, with possible air locks in the coolant system causing over heating. In extreme cases water may fill the cylinder with enough to cause a solid stop of the engine. This may result in bending engine valves or conrod and possible piston damage.

Possible Damage: This situation is serious for the engine, and may go from being driven to instant major damage very quickly.

What to look out for:

  • Low coolant
  • Air in the coolant
  • Darker than normal coolant
  • White exhaust smoke even when the engine is up to running temperature

Other issues that may cause or be mistaken as head gasket failure

  • On K-series Rover engines as in the site model list, two air release valves either could stick
  • Faulty water pump
  • Faulty thermostat
  • Faulty Inlet manifold gasket
  • Faulty water pipe
  • Faulty radiator