The images below show what’s involved in repairing a cylinder head gasket, from the initial strip down to re-assembly. Modern engines are fairly complicated, with numerous additions to help the engines efficiency, smoothness and control. However, the task is fairly straight forward, it just takes time, energy and some mechanical engineering ability. If you’re not planning to do the job yourself, the images may give you an idea of what is involved and why garage costs can be high.
The vehicle in this example is a 2.5 litre, 5 cylinder Land Rover TD5 diesel engine, so it’s of a reasonable size and weight. An engine hoist is used to lift the cylinder head off, as the head still has lots of ancillary components attached, (I have seen others lift this size head off by hand). Smaller engines should be no problem weight wise.
The biggest single components of the engine (excluding the gearbox) are the ‘block’ and the ‘cylinder head’. Most components are contained within, or attached to them.
The cylinder head is placed on top of the block. The two are held together with cylinder head bolts and the joint between the two parts is sealed with a cylinder head gasket.
The head gasket is important because it keeps the engine coolant, oil and combustion gasses from escaping, or mixing with each other.
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Head Gasket Repair – Ready to Start
Remove the Acoustic Cover
Remove the Pipework
Remove the Ancillaries
Remove all the Connections
Remove the Timing Chain
Remove the Head Bolts
Remove the Cylinder Head from Vehicle
Cylinder Head Removed
Check and Clean the Engine Block
Head Gasket Repair – Fit the New Head Gasket
Head Gasket Repair – Replace the Cylinder Head
Tighten the Cylinder Head Bolts
The following is a rough list of the steps required to remove the engine cylinder head.
(These are based on my own experiences):
Symptoms of a ‘blown’ head gasket may be a combination of the following:
The Fault on this Particular Vehicle Was:
Under normal conditions, when the engine is hot, the coolant system is under pressure (due to heat expansion). When the system is cold, there should be little or no pressure.
If the coolant system is pressurised when cold, there must be something in addition to the heating and cooling process pressurising the system. The main source of additional pressure can be from a faulty head gasket, where the engine operation has over pressurised the coolant system.
Water can escape through a faulty head gasket and exit the vehicle through the exhaust, or enter the oil lubricating system. It can also be expelled from the cooling system by over pressurisation as described above.
Oil enters the coolant system through a faulty head gasket, or is burnt, expelled through the exhaust.
The upward movement of the engine’s pistons, compress the air and fuel mixture in each of the engine’s cylinders. If there is a faulty head gasket, the compression is reduced in one or more engine cylinders, as the head gasket seal may be broken and pressure generated by the piston can escape.
There are several tests that can be performed. They may not always directly point to a fault but can provide an indication. Sometimes you have to go on gut instinct and putting 2+2 together because of a combination of fault indicators.
Safety is important – Follow the precautions contained in the vehicle handbook/repair manual. They are there for your safety.
The repair involves:
Additional issues can be discovered, once the head is removed.
The charges for replacing the head gasket can be high due to a large amount of labour, typically 75% (with newer vehicles, a large number of items have to be disconnected to remove the head).
If you have the confidence, performing the task yourself can save the large labour costs.