Head Gasket Failure - How do you confirm?

These cars have acquired a reputation for fragile head gaskets. The original Head gasket is not good at coping with thermal stresses, but there are now uprated multilayer steel replacements that are much better.
The majority of head gasket failure are attributable to loss of coolant.
Therefore it is vital that you monitor the coolant level regularly. Get into the habit of checking it everytime you open the boot. It only takes a second.
The best solution is to fit a LOW COOLANT ALARM. These were fitted to the later model TFs and can be retro-fitted to your car. This will alert you if you suffer from coolant loss from whatever way.
I made my own.

What are the symptoms?
1/. Overheating in traffic/ Steam from the engine bay.
Check the two fans are operating correctly. Radiator fan at the front/engine bay fan at offside air scoop.
If the fans are OK, has the pressure cap failed? Coolant/staining around the top of the expansion tank.

2/. Loss of coolant.
In addition to the above, if the cap is OK, do you have a failed coolant hose? Is there any coolant leaking anywhere? Check under engine/ under length of car/ under front of car.
Weak points are the underfloor pipes(fit stainless steel pipes), early radiators that corrode(fit an alloy core rad), the plastic bleed screw on the nearside of the rad top(visible through the square hole in the crash panel.(Mike Satur does a metal replacement)
If all of the above fail to find your coolant loss, then:-

There are a few more places the coolant could be disappearing. The heater matrix may leak, as can the heater valve.
A common place on cars with the plastic inlet manifold is the manifold gasket. It normally leaks at the end beneath the throttle body, and drops onto the engine and evaporates, hence is an invisible loss. With the engine cover removed, feel under the inlet manifold for moisture, also examine the engine for coolant coloured staining.

4/. Excess steam from the exhaust, even when the engine is warmed up.
The head gasket could have failed.

5/. Unexplained rises in the coolant level.
This can be air in the coolant system. It is important to bleed the cooling system thoroughly. Any air will expand with temperature.
Rises can also be caused by combustion gases escaping past a failed head gasket. Any garage should be able to do a 'SNIFF TEST'
They suck the air above your coolant through an indicator liquid. If it changes colour, then it shows that there are combustion gases present, and confirms head gasket failure.

6/. Oily gunk in the expansion tank/ Creamy mayonnaise instead of oil.
Head gasket definitely gone.
You can sometimes see tiny amounts of white gunk on the dipstick, especially if the car has not been on a good run recently. This is sometime just condensation. There is an argument that this is actually the very first signs of gasket failure. No definitive verdict is presently available on this.


Do not continue to drive the car with symptoms of head gasket failure until it has been checked by a competent person. If the gasket has failed you are likely to do damage to the engine by running the car.