How to Troubleshoot an Overheating Engine

What You'll Need
Replacement fuse

An overheating engine in your car can damage the motor and result in hefty repair bills.  The engine should be checked right away to find out the cause of the overheating. Check the cooling system. The cooling system includes the radiator, water pump, thermostat and cooling fan.

Step 1 - Check Engine Coolant Level

The first step in diagnosing an overheating engine is to check the coolant. If the coolant is low or out, it can cause major engine damage. The coolant level in the reservoir tank should be between the marks labeled hot and cold. It is best to check the level when the engine has cooled down. If the level is low then there may be a leak.

Step 2 - Check Engine Thermostat

An engine thermostat has a valve that opens when the engine warms up. When the thermostat is not working it will stop the coolant from getting to the radiator and overheat or it might be stuck open and overheat. To test the thermostat, drain all of the coolant out and take out the thermostat. Next examine the thermostat to see if there is any damage to it. See if the valve is closed. If it is open then it should be replaced. You can test the thermostat by putting the thermostat in a pot of water turning up the heat. The thermostat should open up just before the water reaches a boil. If it has not opened by the time the water is boiling it should be replaced.

Step 3 - Inspect the Electric Fan

A cooling fan lowers the temperature of the coolant. When the fan is not working, the coolant stays hot and this causes the engine to overheat. To test the fan be sure the car is turned off, spin the blade manually. If it does not spin easily then the fan needs to be replaced. If the fan spins easily then turn the car on. Turn the air conditioner on. The fan should turn on within a few minutes. If it doesn’t come on then change the fuse out to see if that is the problem. Next, check the wiring and components. If the electrical system is working and the fan is not working, it should be replaced.

Step 4 – Test the Radiator

The water pump forces coolant into the radiator. The heat is removed from the coolant via the cooling fins in the radiator tubes. When the radiator is not working properly the heat stays in the coolant and can result in engine overheating. This is a gradual process and is usually noticed when driving uphill or during hot weather.  To test for a radiator problem let the engine cool down. Then drain out the coolant so that you can examine the tubes in the radiator. If the tubes are not clear then replace the radiator.

Step 5 – Examine the Catalytic Converter

The main emission control device on a car is the catalytic converter. It works by converting unburned gas into burned gases. When the catalytic converter is not working correctly it can clog the exhaust system.  This can cause the engine to overload the cooling system and it will overheat. If there is a problem with the catalytic converter then the engine will be losing power. You may need to have the car put on an engine test at an auto parts of repair shop to test the catalytic converter.