A Classic Blown Head Gasket
Cylinder head gaskets are a common repair on most types of vehicles and it is a repair that you may experience depending on the car that you own and the age of the vehicle.
Head gaskets do an amazing job and it is a miracle that they last as long as they do given the tasks they are charged with. The cylinder head gasket provides the seal between the top of your engine block and your cylinder head.
Engine coolant, engine oil and combustion pressures are all sealed by this gasket. Intense heating and high pressures occur at the top of the cylinders. Engine coolant, often above the boiling point of water, as well as oil are pumped under high pressure for cooling or to valves and camshafts for lubrication as well as oil draining back to the oil pan. Extreme temperatures and pressures are part of the head gaskets everyday job.
Head gaskets will fail (or blow, as we like to say in the trade) for many reasons: coolant leaks into the combustion chambers; external coolant or oil leaks; coolant leaks into the oil or oil leaks into the coolant; and sometimes between the cylinders.
That is what happened on this 1991 Volvo 940 Turbo: the gasket blew between #2 and #3 cylinders and the engine ran very roughly.
Head gasket repairs are expensive so preventing them from occurring is in your best financial interest. Besides changing your engine oil and coolant at proper intervals — the only other thing you can do, is to ensure that you never overheat your engine as this will most often cause the gasket to fail prematurely.
Unfortunately some engines have been poorly engineered and their head gaskets fail no matter what you do. If you are considering buying a used car we can tell you the track record of many vehicles: just call us.