The cylinder head gasket should seal combustion chambers, air ducts, oil channels and the cooling system against one another.
How it works
Special soft coatings with metal fringes for the combustion chambers and in particular gaskets with 4 metallic single gaskets (see picture) provide for most (also diesel) engines a service-free assembly.
Tightening up the cylinder head bolts is not necessary because the cylinder head does not gravitate any more. To provide the metallic surface, nevertheless, with sufficient sealing, they are coated.
Defective head gaskets can often be recognised by gas bubbles or engine oil in the cooling system, however, further going compression checks and a pressure loss test are required.
The coolant flows through the cylinder block via channels from the bottom upwards. An open deck design towards the cylinder head requires full metal head gaskets (see picture), for closed decks the head gaskets are softer.
The compression ratio must not be altered because of the danger of a knocking combustion. Therefore, the space between cylinder head and TDC must always remain the same also after changing the cylinder head. If the cylinder head has been levelled because of unevenness, the material that has been taken off must be compensated for by an accordingly thicker head gasket.
No component is able to ward off electronics. In the meantime, there are already head gaskets with integrated temperature sensor. 06/08