Symptoms

1. The water temperature gauge indicates a value exceeding the specified limit (diesel engine water temperature ≤ 90°C);

2. The coolant in the radiator is extremely hot or even boiling;

3. The diesel engine's power output decreases;

4. The diesel engine is difficult to shut off.

Causes

1. Water leakage or insufficient coolant;

2. Fan belt is too loose;

3. Fan blades are improperly angled or damaged;

4. Water pump is worn, leaking, or has reduced pumping capacity;

5. Diesel engine operates at low speed under heavy load for extended periods;

6. Fuel injection timing is too late;

7. Thermostat malfunctions;

8. Clogged water distributor pipe;

9. Excessive scale buildup in the water jacket, resulting in poor heat dissipation.

Troubleshooting Methods

1. Inspect the diesel engine for leaks and check the radiator for low water levels. Then check the tension of the fan belt. If the fan belt is not loose, inspect the installation angle of the fan blades, check for damaged fan blades, and assess the wear condition and pumping capacity of the water pump.

 2. Check if the diesel engine has been operating at low speed under heavy load for an extended period. Check if the fuel injection timing is too late. A prominent characteristic of delayed fuel injection timing is: loud exhaust noise, black smoke from the exhaust, weak engine performance, and a significant drop in power.  

 3. Check if the thermostat is malfunctioning. A malfunctioning thermostat is characterized by: high coolant temperature inside the diesel engine and low water temperature in the radiator. At this point, remove the thermostat from the diesel engine and restart the engine. If the water temperature of the diesel engine is normal, it indicates that the thermostat is faulty. If there is partial blockage in the radiator pipes, it can also cause the water temperature of the diesel engine to rise too quickly.  

 4. If there is excessive scale buildup in the radiator cooling water jacket or the water distributor pipe is not functioning properly, touching the cylinder block will reveal uneven temperatures.