It’s getting hot: 7 causes for the radiator to boil

We looked at why the engine can get hot and how you can find the cause.


1. too little water in the radiator

Small hole, big effect: The most common cause of overheating is actually a leaking cooling system. With the right test tool, you can quickly and easily determine whether everything is tight and whether you have enough fluid in the cooling circuit. The best thing is that the rental toolboxes from MOBILITY MARKET always come with digital instructions on how to use them.

2. defective thermostat

If the temperature display on the dashboard offers no clue as to whether the thermostat is broken, the only thing that can help is a thermostat check. This check can be done easily and quickly:

  • Put the thermostat in a pot of cold water without it touching the bottom.
  • Heat the water on the stove.
  • Use a cooking thermometer to check the temperature at which the thermostat opens.

3. air in the cooling system

In this case, the old coolant and air must go out and new coolant must go in. Sounds simple, but it is not always. Many vehicles require special tools to fill the cooling circuit. The easiest and fastest way is with this filling tool from MOBILITY MARKET. Of course, the digital instructions for filling are also available in the rental tool kit.

4. the V-belt that drives the water pump is too loose.

The only thing that helps is tensioning or, if the belt is already visibly worn, replacing it.

5. fan does not work

This is usually the case if the coupling of the viscous fan or the thermal switch or the fuse of the electric fan is defective. This can be found out if you check the viscous fan’s power connection (cold/warm) and if you check the electric fan’s rotation when the engine is hot.

6. cooler net is too dirty.

If there is too much dirt in the radiator network, it is best to clean it carefully with compressed air.

7. ignition set incorrectly or carburetor set too lean.

This is something for automotive repair professionals like you. This is because older vehicles with carburetors require a delicate touch when it comes to adjustment. The same applies to an incorrectly adjusted ignition.