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How much does a head gasket cost to replace

The Main Signs Your Car’s Head Gasket Has Blown

The signs and symptoms of a blown head gasket in your car are not always immediately obvious. Understanding how the head gasket works can be the best way to ensure that you are going in the right direction towards making a successful diagnosis and repair of the problem. Along with electrical actuators and sensors, modern car combustion engines rely on liquids and gases to function, including engine oil and engine coolant. The design of modern engines prevents these liquids from mixing with one another so that they are able to perform their specific functions correctly. The head gasket is a component that is mounted between the engine block and the cylinder head to perform a range of essential functions.

How Much To Replace Head Gasket – What Does the Head Gasket Do?

Upon combustion, fuel and air can generate more than 700psi in a petrol engine and more than 2000psi in a diesel engine. The head gasket not only needs to be installed correctly but also in good condition for this pressure to be kept inside the combustion chamber.

The main aim of the head gasket is to prevent gases and liquids from escaping into the cylinders adjacent to it and the surrounding coolant and oil galleries. Each cylinder is surrounded by coolant to maintain a stable operating temperature and ensure that the engine does not overheat. It needs to flow into the heads of the cylinders to cool the spark plugs, combustion chamber, and valves.

The main purpose of the head gasket is to prevent coolant from entering cylinders between power strokes and when the engine is switched off. Along with this, there is also engine oil, which also provides cooling along with hydraulics and lubrication. The oil pump sends pressurised oil throughout the engine to provide lubrication to all the moving parts including bushings, bearings, timing chains, and journals. It also drives hydraulic actuators including variable valve timing.

The head gasket is also in place to prevent engine oil from getting into the coolant, cylinders, and between power strokes.

Head Gasket Repair Cost – How to Tell if a Head Gasket Has Failed

A failed head gasket is not always immediately obvious, and sometimes the signs and symptoms are quite subtle. Depending on the type of car, it may cost thousands of dollars to replace the head gasket. Before you spend a lot of money on getting a new head gasket for your car, it’s a good idea to perform your own diagnosis to determine if this is really the problem. Some of the main tell-tale signs that your car has a blown head gasket include:

Bubbles in the Radiator

Bubbles in the radiator is one sign of a head gasket that has blown. To check for this, first turn off your car’s engine and wait until it has fully cooled, which is usually around two hours after driving. Use a towel or rag to carefully remove the radiator cap, and then rev your car while observing the coolant as it travels across the radiator’s filler neck. Some bubbles are normal as this could simply be trapped air escaping the cooling system. However, it might be a sign of a blown head gasket if the bubbles are still persisting after twenty minutes of engine idling. Combustion gases can enter the cooling system if the head gasket has blown, which can lead to bubbling in the radiator. When the head gasket is in good condition, it will seal the cylinder head and engine block to prevent the combustion gases from leaking.

White Exhaust Smoke

Next time you start your car, it’s worth checking the exhaust to determine if your head gasket has blown. White smoke billowing from the exhaust tailpipe is a major sign of a blown head gasket. If you have a petrol engine, then the exhaust smoke should be invisible and clear. If the smoke is white, then this will usually indicate moisture in the combustion chamber. A blown head gasket is the only thing that can cause a substantial amount of moisture to enter this engine component. Coolant may be able to enter the combustion chamber depending on where the head gasket has blown. Since air and fuel is heated here, the coolant will also be heated, which causes the exhaust smoke to be white in colour.

Mixed Coolant and Oil

Coolant and oil mixing in the engine is another major sign that the head gasket has blown. There should not be any coolant in the oil or oil in the coolant under any circumstances when the head gasket is in good condition.

The main chemical that is used to make antifreeze in the coolant, known as ethylene glycol, is not effective at lubricating. If the coolant gets into the passages for the engine oil, then it could lead to serious internal degradation of the engine and even shorten the lifespan of the car, leading to a complete breakdown if it is not rectified quickly.

On the other hand, oil getting into the coolant is equally as damaging since the oil does not transfer heat as quickly as coolant, so this can lead to serious overheating.

You should look inside the radiator and check the oil dipstick to check if your car’s coolant and engine oil are mixing. When coolant has gotten inside the oil, this will usually have a foamy consistency and soft cream colour. Oil inside the coolant will show up as black specks that float to the top of the radiator.

Cooling System Pressure Loss

The cooling system in your car is designed to pressurise while the engine warms up. Once you have been driving for just a few minutes, the coolant collects enough heat to pressurise and expand the cooling system. Pressurised coolant has a lower boiling point compared to unpressurised, which prevents it from boiling over and turning to steam. However, when the head gasket is blown, this can lead to a loss of pressure in the cooling system as the closed nature of the system is broken. When the head gasket blows between a cylinder chamber and a coolant passage, this can cause coolant to leak into the chamber, which prevents the system from maintaining the correct pressure. You can find kits at most car parts stores that you can use to check if your car’s cooling system is maintaining the right pressure.

Hard or Rough Starting

If you are having trouble with getting your car started, or the car is running rough when starting the engine, then this could be a sign of a blown head gasket. This happens when the coolant has flooded one or more of the cylinder chambers, which prevents the combination of fuel or air from igniting correctly. If the cylinder chambers are not dry, combustion may not occur, which can lead to issues with starting your car.

Cylinder Compression Loss

Loss of compression in at least one of the cylinders is another main sign that the head gasket may have blown. The purpose of the cylinders is to trap combustion gases and create as much energy as possible, which is then used to power the crankshaft and enable the car to move. If there is cylinder compression loss, then your car may perform sluggishly, or you may not even notice much of a difference in the handling or performance. The best way to check for this issue is to test the cylinders, which you can do using either a compression test or a leakdown test.

Overheating Engine

It’s important to check your car’s engine temperature as you are driving. An overheating engine can cause the head gasket to blow, or it can also be a sign that the head gasket has already blown. When exhaust gases enter the cooling system due to a damaged head gasket, for example, this will quickly heat up the coolant and cause it to no longer be effective in keeping the engine cool.

How Much Does a Head Gasket Cost – What to Do If Your Head Gasket Has Blown

If your head gasket has blown or you suspect that this has happened due to noticing the above signs, then you should avoid driving your car to reduce the risk of severe damage to the engine. It is a good idea to have it towed or hire a mobile mechanic to come to your home and replace the head gasket. Replacing a head gasket is not a cheap or easy job; while the head gasket itself is a relatively inexpensive part, you will usually be paying mostly for the mechanic’s labour since it can take more than twelve hours for an old head gasket to be removed and a new one to be fitted. The mechanic will also check the cylinder head to determine if it is warped; it will need milling before a new head gasket is fitted if it is not completely flat.

A blown head gasket might not be noticeable straight away, but it can cause serious problems or even a complete breakdown of your car’s engine.


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