Fault Phenomenon: Hyundai 25D-7E diesel forklift after one hour of operation, the water temperature gauge enters the red zone, the radiator boils, and engine power drops.

Troubleshooting Process:
– Checked radiator fan: fan belt broken.
– Checked coolant level: level normal.
– Checked thermostat: opens normally.
– Checked water pump: water pump impeller corroded.

Root Cause: Broken fan belt causes no airflow through the radiator for cooling.

Required Parts: Fan belt and tensioner pulley.