The coolant hoses are faulty.

Replace the hoses, as necessary.

Refer to Radiator Hose Replacement .

The drive belts are faulty.

1. Replace the belts.
2. Adjust the belt tension.

Refer to Engine Mechanical.

The coolant hose clamps are faulty.

Replace the clamps, as necessary.

Refer to Radiator Hose Replacement .

The coolant drain plugs are loose.

Tighten the coolant drain plugs.

The radiator drain cock is loose.

Tighten the radiator drain cock as needed.

The radiator core is leaking.

Repair the radiator core as needed.

Refer to Radiator Replacement .

The gaskets are leaking.

Repair or replace the gaskets as needed.

The radiator cap is faulty.

Replace the radiator cap.

The belt tension is incorrect.

Adjust the belt tension.

Refer to Engine Mechanical.

The radiator is restricted.

Repair the restriction as needed.

Refer to Radiator Cleaning .

The radiator grille is blocked.

Repair the grille as needed.

Refer to Radiator Cleaning .

The radiator shroud or the baffles are missing.

Install the correct radiator shroud or baffles.

Refer to Fan Shroud Replacement or Radiator Lower Mounting Panel Replacement .

The water pump is faulty.

Replace the water pump.

Refer to Water Pump Replacement .

The cooling fan is faulty.

Replace the fan.

Refer to Fan Replacement .

The thermostatic fan clutch is faulty.

Replace the thermostatic fan clutch.

Refer to Engine Mechanical.

The cooling system is plugged.

1. Repair the cooling system as needed.
2. Drain the system.

Refer to Cooling System Draining and Filling .

3. Flush the system.

Refer to Flushing .

The engine thermostat is faulty.

Replace the thermostat.

Refer to Engine Coolant Thermostat Replacement .

The engine thermostat is incorrect.

Install the correct thermostat.

Refer to Engine Coolant Thermostat Replacement .

The surge tank is faulty.

Repair or replace the surge tank.

Refer to Surge Tank (Diesel) Replacement .

The heater hoses or the heater core is plugged.

Repair or replace the heater hoses of the heater core, as necessary.

The head gasket is leaking.

Repair or replace the head gasket, as necessary.

The engine temperature gauge sensor is faulty.

Replace the engine temperature gauge sensor.

Refer to Engine Coolant Temperature Sensor Replacement in Body and Accessories.