The purpose of using a gasket when joining two metal components in an engine is to prevent leakage of the coolant or oil system either out of the engine or to avoid them mixing within the engine. A typical sign of when this has happens is when you notice that there is a lot of blue smoke coming from the exhaust, if you see this then you should stop the tractor and seek professional help to resolve the issue before irreparable damage is caused. Earlier gaskets where made of cork but modern tractor engines use thin metals ones, or in some circumstances, they use gaskets made from carbon.

While it is important that gaskets are replaced when a leak is detected, it is just as important to replace them when any corresponding components of the engine are replaced, such as the cylinder head.