actually, there is a kit u can get in the states (not sure about the UN-states) that you use to get a sample of the rad. fluid when hot and run it through a chemical check. when the head/gasket leaks, the fluid gets basic (or acidic, too late too remember) from the exhuast gasses. you put this thing where the cap goes and hodl it down the get the motor warm. you put a little bit of the chemical chekcer in it and if it turns color, you have exhuast gasses in the rad. which means bad gasket or head. if you can find the kit it will come with much better instructions.