Symptom:  Engine overheating in heavy trucks, especially under heavy load or in hot weather.

Possible Cause & Solution: One common cause of overheating in heavy trucks is a malfunctioning thermostat. The thermostat regulates engine temperature by controlling coolant flow. If it's stuck closed, it can prevent coolant from reaching the radiator, leading to overheating.

Detailed Solution:

1. Safety First: Allow the engine to cool down completely before attempting any work.

2. Locate the Thermostat Housing: Typically found where the upper radiator hose connects to the engine.

3. Drain Coolant (Partially): Drain enough coolant to lower the level below the thermostat housing to prevent spillage.

4. Remove Thermostat Housing: Unbolt the thermostat housing. Note the orientation of the thermostat as you remove it.

5. Inspect the Thermostat: Check if the thermostat is stuck closed or shows signs of damage.

6. Test the Thermostat (Optional): Place the thermostat in a pot of hot water. If it's working correctly, it should start to open as the water heats up.

7. Replace the Thermostat: If faulty, replace it with a new thermostat of the correct temperature rating for your truck model. Ensure the new thermostat is installed in the correct orientation.

8. Replace Gasket/O-ring: Use a new gasket or O-ring for the thermostat housing to ensure a proper seal.

9. Reassemble and Refill Coolant: Reattach the thermostat housing, tighten bolts to the correct torque, and refill the cooling system with the correct type and mixture of coolant.

10. Bleed the System:  Start the engine and let it warm up with the radiator cap off (or use a bleeding procedure specific to your truck model) to remove air pockets from the cooling system.

11. Monitor Temperature: After repair, monitor the engine temperature gauge to ensure the overheating issue is resolved.

Regular maintenance and prompt attention to cooling system issues can prevent costly breakdowns and ensure the reliable operation of your heavy truck or other engineering machinery.