The head gasket creates a sealed boundary between the combustion chambers in the cylinder head and the oil and coolant passages in the engine block below. It operates under extreme heat and pressure. When it fails, the results show up quickly and unmistakably. At KITH Cars Garage in Hackbridge, head gasket work is escalated to Giles, our workshop manager, before any work begins. It is not a job that benefits from being rushed.
Overheating is the most common cause of head gasket failure. An aluminium cylinder head expands under heat at a different rate to the cast iron or aluminium block it sits on. The gasket absorbs that stress. One severe overheating event can be enough to blow a gasket. Repeated mild overheating from a slow coolant leak or a partially blocked radiator does the same thing over a longer period.
There are a few ways the failure presents. Coolant entering the combustion chamber produces thick, sweet-smelling white smoke from the exhaust. Combustion gases entering the cooling system cause bubbling in the header tank and gradual coolant loss with no visible external leak. Oil and coolant mixing creates the characteristic creamy emulsion on the underside of the filler cap. Some gaskets fail externally, producing a visible leak between the head and block.
Every head gasket job at KITH Cars Garage starts with a thorough inspection before anything is removed. We check for cracks in the cylinder head with a dye penetrant test. We measure the head surface for flatness with a straight edge. A warped head must go to a machine shop for surface grinding before a new gasket is fitted. Fitting a new gasket to a warped surface is a reliable way to fail again within a few thousand miles.
We use quality gasket sets. Elring, Goetze or equivalent depending on the engine. Head bolts are replaced as a matter of course because most modern engines use torque-to-yield bolts designed for single use. The cooling system is flushed completely and refilled with the correct coolant mix. Engine oil and filter are changed as part of the job. Nothing from the old oil stays in the engine.
After reassembly, the engine is brought to operating temperature and held there while we monitor coolant level, operating temperature and pressure. A road test follows. Where possible we hold the vehicle for 24 hours before return to confirm the repair is stable under normal operating conditions.
