How does head gasket work

The head gasket keeps the chambers separated to ensure there is no cross-contamination of fluids. The most common cause of a blown, or damaged, the head gasket is often a result of an engine that has gotten too hot.

High engine temperatures are usually caused by a lack of coolant within the radiator, usually due to a leak. Some gaskets are likely to weaken sooner than others depending on their material.

Aluminum, for example, expands faster when heated. Metals that have a higher thermal expansion rate are more sensitive to heat. Higher temperatures can cause the object to change shape, producing an unfavorable outcome. Expansion and distortion of the cylinder head as a result of heat weakens its integrity preventing the head gasket from sealing properly.

Continuing to operate a vehicle with a blown gasket can cause serious and irreparable damage to the engine. As the gasket is used as a seal, maintaining pressure is the key to engine power. When coolant enters the combustion chambers, it mixes and dilutes the engine oil, while also decreasing the cooling capabilities of the cooling system, which may cause engine overheating. The engine relies on three vital fluids in order to run: fuel, coolant, and motor oil. If the gasket blows, all fluids may enter into or out of the combustion chamber.

You may notice a few or all of the following:. Extensive damage to the engine as a result of a blown head gasket is the most unfavorable kind of engine problem. A busted head gasket that is ignored may require repair of the engine block, cylinder heads, or a complete engine replacement. What is a Brake Bleeding Kit? What is a timing chain? Get complete car advice. Get your Car ready for the Cold Season. What are strut mounts?

What does a fuel filter do? Car accident report: the procedures. Get quotes. All repair types Airconditioning. Car Accessories. Car Battery. Car Care. Car Servicing. Damage Repair. Electrical Work. Head Gasket. Oil Change. Inside an engine you have a piston going up and down within a cylinder. In order to form a good seal around the top of the cylinder, the head gasket features steel rings, known as fire rings.

These are actually crushed when the cylinder head is tightened onto the engine block to provide a seal capable of dealing with the high temperatures and pressures involved. Most modern head gaskets are made from multiple layers of steel MLS. Typically these use three steel layers; the centre layer is slightly thicker, while the two thinner outer layers are coated in rubber-like high temperature and chemical resistant polymers most commonly Viton which helps the contact faces seal against the cylinder head and engine block.

Earlier head gaskets were often made from composite material often referred to as fibre head gaskets , typically graphite-based coated in a wax-like finish, and with beads of silicone around the waterways and oilways to aid sealing. These, older, composite head gaskets are more prone to failure than modern MLS gaskets, but many MLS replacements are now available for older engines that would have been produced with a composite gasket when new.

The most common cause of a blown head gasket is engine overheating. When the engine gets too hot, the cylinder head expands thermal expansion , which can crush the head gasket and cause failure. The most common cause of engine overheating is a low coolant level.

This may be because of poor maintenance, or more likely to be because of a coolant leak. Water conducts heat 13 times better than air. So once the coolant level drops, the engine will quickly overheat. Other likely causes of an overheating engine are a faulty thermostat, faulty electric cooling fan, or blocked coolant passages in the engine. This could get expensive…. Get more free car maintenance help with the Haynes Home Mechanic Guides.

This loss of compression results in a rough-running engine and a notable reduction in engine power. With a head gasket that is only slightly leaking, very small quantities of coolant can leak into the combustion chambers when the vehicle is parked up and left overnight. The next time the engine is started, it can misfire on one or more cylinders. This may only last a few seconds until the coolant is cleared, but should be taken as a sign — it can only get worse!

Be careful though, as this symptom is more commonly a sign of condensation mixing with the engine oil. A faulty head gasket can also allow engine oil to leak into the coolant passages in the cylinder head. Again, be careful though, as this can also be caused by a leaking engine oil cooler or transmission oil cooler. This can be very bad news for the catalytic converter. If a head gasket has failed between the waterway or oilway and the outside of the engine, the result can be a simple coolant or oil leak.

This may not manifest itself as an immediate problem other than causing a mess but if the coolant or oil levels are allowed to drop too far it can lead to serious engine issues. A failed head gasket can allow combustion gasses into the coolant passages, which may pressurise the coolant system, and cause an external coolant leak from any weak spot in the system. At the very least, the cylinder head must be removed along with the old gasket.