With a cool engine, simply remove the radiator cap and attach it to the tester. Then hand-pump the tester to capacity and check the needle to see whether the cap is holding pressure to its rated specification. Much like the gaskets in the radiator cap, the hoses in your cooling system can weaken over time and rupture when heat and pressure reach a certain point. A periodic careful inspection of all the hoses in your cooling, as well as the clamps that hold them attached, will help you identify trouble-spots before a system breakdown occurs. Check the condition of belts .
Belts can break or become stretched, glazed or frayed.
If belts become ineffective in turning the radiator fan, for instance, this may be another cause for overheating. If a fan belt is slipping, you may be able to help the situation by tightening the belt or using a belt dressing. It's generally best, however, simply to replace the belt. Other problems that can contribute to engine overheating include a faulty thermostat or a water pump that's not working. If these parts fail, it's best to stop the car and seek the assistance of a mechanic.