Tech Tips

Troubleshooting - Engine Overheat Check List

Applies To:

Discovery I | '94-'99
Range Rover Classic | '90-'95
Defender 90 | '94-'97
Defender 110 | '93

Does the cooling system lose fluid? Pressure test for leaks.

• Check for obstructions of airflow through the radiator. Especially check between the radiator and the A/C condenser.
• Check operation of the auxiliary fans (they should come on when the A/C is on).
• Check the operation of the fan viscous coupling. It should not be freewheeling when the engine is hot. It also should not be locked up solid.
• Inspect the water pump, making sure there is no play in the shaft.
• Remove the engine thermostat and see if it is stuck half open. You can test it by warming it in a pan of water on the stove and see what temperature it opens. It should open fully at around 185°F.

If all of the above check okay, the radiator can have restricted flow internally. This needs to be checked by a radiator shop. What happens is the ends of the core tubes get deposits built up on them and the coolant can't flow through. It then needs to be reamed out or the core replaced.

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