What is the head gasket?
The engine head gasket is a component located between the engine block and the engine head. Its purpose is to perfectly seal the combustion chamber allowing the car to generate proper compression and contain the exhaust gases, ensuring efficient engine operation.
The engine head gasket is, for all intents and purposes, a gasket made of different materials, including rubber, ceramic andmetal inserts. The exact composition and construction varies from model to model, but the basic principle remains the same: to perfectly seal the engine unit.
The head gasket also keeps coolant and engine oil out of the combustion chamber but inside the engine block, preventing possible leakage of these fluids.
The engine head gasket is maintenance free and should never be replaced unless there are problems. Due to its proximity to hot engine parts, the gasket can wear out and cause the dreaded "burnt head gasket" problem.
Why does the head gasket burn out?
As we have seen, the engine head gasket seals the engine block to the engine head perfectly. This means that the cylinder head gasket must contain both the very high pressure hot combustion gases and the coolant which may be at ambient or normal engine operating temperatures.
Because of these high stresses and large temperature fluctuations, it is not unusual for the engine head gasket to develop leaks over time. This problem can occur regardless of the car model or type of engine head gasket used.
Since it is not very visible from the outside and when the engine is assembled it is difficult, if not impossible, to assess the state and condition of the engine head gasket. For this reason, knowing how to recognize the symptoms of a burnt head gasket is crucial to notice the problem and react immediately to avoid making the situation worse.
What are the symptoms of a burnt head gasket?
The symptoms of a burnt head gasket are very different but equally important. Here is a list of the 7 most common symptoms of a burnt head gasket:
- Engine overheating
- Loss of power
- Engine oil contamination
- Sweet white smoke
- Loss of engine fluids
- Air bubbles in radiator
- Dirty candles
First symptom of a burnt head gasket: engine overheating
The first and perhaps most dreaded symptom of a burnt engine head gasket is engine overheating. The engine overheats when the coolant (or water) temperature exceeds the normal temperature of 80-90°. The water temperature warning light comes to our rescue and when it is on it clearly indicates engine overheating.
In case of a burnt head gasket there may be a leak of coolant out of the engine. This loss of coolant or water prevents the removal of heat from the engine which will inevitably overheat.
Another problem can be damage to the engine head gasket, causing oil or combustion residue to leak into the coolant. If fouled, the coolant cannot be adequately cooled by the radiator and will cause the engine temperature to rise.
Engine overheating is perhaps the worst symptom of a burnt head gasket, as the lack of immediate reaction can cause enormous damage to the machine. If the metal exceeds normal temperatures it can melt or become damaged, making it necessary to replace the entire engine block including cylinder heads, valves and cylinders.
We are talking about several thousand euros of damage and for this reason we recommend always keeping the coolant temperature under control.
2nd symptom of a burnt head gasket: power loss
If intact, the engine head gasket ensures correct compression of the combustion gases and makes the engine very efficient in terms of fuel consumption and power. Conversely, a burnt head gasket causes the engine to lose power.
One of the symptoms of a burnt head gasket is loss of engine power. A burnt head gasket allows combustion gases to escape from the cylinder and decrease the power produced by that specific cylinder.
If you press the throttle deeply, you will notice a distinct loss of power, possibly accompanied by a metallic whistle.
Third Symptom of a Burnt Head Gasket: Engine Oil Contamination
One of the most well-known symptoms of a burnt head gasket is the presence of contamination within the engine oil. Evidence of such contamination is the presence of a white sludge under the engine oil cap or at the bottom of the engine oil dipstick.
If this white sludge is present, then the burned head gasket will probably allow coolant to enter the engine oil system.
This contamination contaminates the engine oil and therefore makes it unsuitable for its role in lubricating engine components. Engine bearings are one of the first components to be damaged if you continue to drive with oil mixed with coolant.
This symptom of a burnt head gasket forces the driver to set aside a complete oil change with oil filter change. In the worst case, it may be necessary to remove the lower part of the engine to check the bearings for wear.
Fourth symptom of a burnt head gasket: sweet white smoke.
Apparently one of the strangest symptoms of burnt head gasket is the presence of a white, sweet smoke coming out of the exhaust pipe. This phenomenon is due to a leakage of coolant and/or engine oil inside the engine cylinders where, due to the heat, it turns into steam and smokes out of the muffler.
This phenomenon also becomes evident if the pressure of the combustion gases entering the cooling system ruptures one or more radiator tubes, causing a considerable loss of water and an immediate rise in coolant temperature.
Needless to say, the only thing to do in this case is to stop the car safely as soon as possible and call a tow truck immediately.
5th symptom of a burnt head gasket: engine fluid leakage
If every time we move the car from the parking lot we notice the presence of oil or coolant under the engine, then we may have a problem. However, this burnt head gasket symptom is not easy to notice, especially when parked on the road.
This is perhaps the least worrisome symptom of a burnt head gasket because the problem could be limited to the gasket and not the other parts of the engine.
Very often, fluid leaking from the engine due to a burnt head gasket will cause theengine oil warning light to come on. In this case we recommend that you read the article where we explain what to do with an oil warning light on.
Sixth symptom of a burnt head gasket: air bubbles in the radiator.
The presence of bubbles in the car's radiator, even at low temperatures, is a clear symptom of a burnt head gasket. This is because the burnt head gasket allows combustion gas to enter the cooling circuit to the radiator.
This symptom is virtually impossible to notice unless the coolant has to be topped up due to a low level which in itself is already indicative of potential problems with the car. If we are forced to top up the coolant regularly, then there is definitely a leak that needs to be rectified to avoid dangerous overheating of the engine.
7th symptom of a burnt head gasket: fouled spark plugs
If the spark plugs are fouled with whitish residue, especially near the electrodes, then we may have a problem with the engine head gasket.
This symptom of a burnt head gasket is not easy to notice but is still helpful when cleaning or replacing spark plugs.
Can the burnt head gasket walk?
Many people wonder if you can walk with a burnt head gasket. The short answer is no, because moving a car with a damaged head gasket can cause serious engine damage.
That said, if the gasket is not seriously damaged and there are only minor symptoms of damage, then the driver , at their own risk, may choose to drive the car very slowly to the mechanic. If the distance is too long, then driving slowly will be futile because the engine will reach very high temperatures in any case.
Replacement of burnt head gasket cost?
Due to the variety of head gaskets and car models it is impossible to indicate a general price for replacement. We must always keep in mind that in this type of intervention the cost of replacement is nothing compared to the hours of work required to perform it.
Therefore, the cost of replacing a burnt head gasket depends more on the mechanic's hourly rate than on the type of gasket required. The latter usually does not exceed a few hundred euros, while the many hours of work can easily exceed 500 euros.
Being aware of the symptoms of a burnt head gasket helps us to save a lot of time and money in the maintenance of our vehicle.