The head gasket is a gasket that sits between the cylinder head and the cylinder block with a primary function of tightening the seal between these two components. Despite this simple-sounding function, the head gasket is actually one of the most critical gaskets used in a vehicle. Aside from sealing the cylinder head and block, the BMW head gasket also seal the combustion chambers, coolant passages and oil passages between the head and block. This is the reason why whenever the head gasket of your BMW fails, an intermixing between the combustion gas, oil, and coolant could be easily noticed.
There are many possible causes of head gasket failure, although all of them can be categorized into three. The first category would be those failures resulting from design issues with the engine or the gasket. An example of this problem is the use of different metals with different thermal expansion characteristics for the cylinder head and block. The second category, on the other hand, would refer to those problems resulting from improper head gasket installation. Then, the third category would refer to head gasket failures caused by stressful operating conditions like engine overheating, detonation and pre-ignition.
But whatever the cause is, it is important that a blown or damaged BMW head gasket be replaced immediately before your BMW starts losing a lot of lubricant oil or coolant. Head gasket replacements, however, may cost a bit high. The replacement BMW head gasket in itself is affordable but the labor cost would surely pump up the price.