Understanding why a relatively inexpensive head gasket costs so much to replace means first realizing what it sits between. In the engine block are pistons that travel up and down in cylinder bores. The pistons are connected to rods, which in turn are connected to a spinning crankshaft from which the vehicle takes its power. Bolted to the top of the engine is the cylinder head. Inside the cylinder head are valves that open and close to let air and fuel into the cylinders and expel the spent exhaust gas.
The head gasket is compressed between the engine block and the cylinder head. The head gasket seals in the internal combustion process and also keeps coolant and oil from mixing together as the two fluids travel from the engine block to the cylinder head. Head gaskets themselves are not very expensive. What ends up costing big money is getting to it. Removing and replacing the head gasket means undertaking the major operation of removing an engine's head.
A head gasket can fail for a number of reasons, none of them good. Engine overheating is the most popular culprit. The metal of the engine block and head expands beyond limits during overheating. This expansion can pinch the head gasket to the point where it will fail. The next major causes of head gasket failure are engine pre-ignition or detonation. The crux of these two conditions is out-of-time combustion occurring in the cylinders. Internal combustion is supposed to occur with both valves closed and with the piston at the top of its power stroke. Out of time combustion puts extra strain on the valves, pistons, and head gasket. Ironically, engine overheating can also increase the likelihood of pre-ignition and detonation. The sound of an engine pinging or knocking is the insidious sound of damage.
Here at Grimsdyke we can repair and replace most headgaskets. We will carry out a number checks to determine whether your head gasket has gone. The majority of head gasket failure is repairable with a fixed price given although sometimes there is damage to the inside of the engine which we will not be able to see untill the cylinder head is removed which could result in extra costs.
If you think your vehicle has the symptoms of a failed headgasket please bring it in and we will be happy to have a look.