For People that have experienced a head gasket failure, they know better than to keep driving their overheating car, especially after spending a fortune on replacement labour costs.
Spending a small amount on prevention is much better than spending a sizable amount on cure when it comes to head gaskets. While the replacement head gasket itself is not expensive, but the repair is very labour intensive, which significantly increases the cost of repair, especially on modern cars.
Head gasket failures are usually caused by repeated overheating or continuing to drive after the car has overheated, so the best way to prevent a head gasket failure is to ensure your cooling system is in good condition. And if your car does start to boil over, stop, let it cool for at least an hour, and refill the radiator before continuing.
Checking the cooling system is quite easy. All you need to do is to ensure there are no leaks, that the radiator is working efficiently, the thermostat opens properly, and the coolant is topped up to the correct level.
There is also a need for you to make sure that the fan (mechanical or electric) is working, has all of its blades, and has a shroud around it to increase the efficiency.
If you suspect a head gasket failure, the scientific test is to check for combustion gasses in the cooling system. This test will show if the compression has leaked into the cooling system, and therefore if the head gasket has blown. The old mechanic’s trick is to take off the radiator cap, start the car, and look for bubbles in the coolant.
However, these will not show if there are any other failure spots within the head gasket, so the absence of gasses in the cooling system does not guarantee a healthy head gasket.
Some older head gaskets can just fail because they are of a poor design, and are not strong or robust enough for the application they are being used for. This used to be more of an issue with older style, metal gaskets, which could only last for a couple of years of going from cold to hot with every startup before an inevitable failure.
Thankfully modern MLS (multiple layer steel) replacement gaskets are now available for most applications, and offer improved reliability over the original gasket design.