There are many reasons why any car overheats. It is never a case of.. it is this or it is that. There are a few things to go through first to find out the reason.
First and foremost, if a car overheats 'all the time' The first thing to check is the head gasket. I can only give you the basics but check the expansion tank cap to see if there is a white gunk and also under the oil filler cap. Also you may hear a gargling noise coming from the engine compartment. All of this suggests the head gasket has gone.
However, that aside It is important to check the water pump as if this has gone it will over heat. Water pumps are hard to check but as a rule of thumb if they make a noise or leak.. they have gone.
Clean all your pipes out (I found the easiest way to do this is to take 2 pipes off one either side of a union and push water down one of the pipes using a hose pipe. This will flush out the system, Also use Radwelds radiator flush. To clean out all the corrosion and gunk.
Also your temperature sensor may of gone. The easiest way to check this is to replace it.
Thermostat gone, to check this remove it from the car (Usually attached to the radiator inside a pipe or housing) and immerse the cold sensor in hot water if it opens it works, if it doesn't it needs replacing.
Finally, make sure the correct level of coolant is being used.
Obviously if the head gasket has gone, you are looking at an expensive repair and depending on the age of the car and your DIY skills. It is sometimes cheaper to scrap the car. However there is a lot on the internet in how to change a head gasket and believe it or not, it is not as daunting as it sounds, with the right tools you are looking at a couple of hours job. The best book to buy is obviously a Haynes manual and in situations like this are invaluable in finding out what and where a problem comes from.
I hope that helps.
Kindest regards
Aufo8mycow
Sean Marson, September 2006
