What Causes High Water Temperature in Heavy Trucks?

[VonAsher]

High water temperature in trucks may be caused by insufficient or inappropriate coolant. Below are detailed reasons for high water temperature in trucks: 1. Insufficient or inappropriate coolant: Due to the extremely high internal temperatures during operation, diesel engines have strict requirements for the coolant used. If the coolant is severely insufficient, it cannot promptly dissipate the heat generated by engine components, leading to excessively high water temperatures. 2. Cooling fan malfunction: When the vehicle operates at high speeds, the generated heat cannot be efficiently transferred to the antifreeze, affecting heat dissipation. This results in an increase in antifreeze temperature, leading to issues such as overheating.

[SanTaylor]

As a veteran truck driver with over a decade of experience, I can tell you that high engine temperature is most likely a cooling system issue. The most common problem is a clogged radiator – after years of long-haul driving, dead insects and dust get packed into the radiator fins. Loose or broken fan belts can prevent the fan from spinning, causing heat buildup. A faulty thermostat is the most critical issue – it fails to open the circulation valve when the engine warms up. Corroded water pump impellers are also common, preventing coolant flow. Engine problems like poor fuel injector atomization or mistimed ignition can also cause excess heat. Always check coolant level and color before trips. If you notice the temperature gauge rising during driving, immediately turn off the AC and turn on the heater to assist with cooling.

[SanCamilla]

After years of repairing heavy trucks, when encountering high water temperature, I usually check by feeling the temperature of the hoses first. If the upper hose of the radiator is hot while the lower one is cold, it's definitely a stuck thermostat; excessive foam in the coolant indicates a blown cylinder head gasket, allowing exhaust gases to mix into the cooling system; deformed radiator fins or blockage by poplar fluff can obstruct airflow, which is also a common issue. Be cautious of abnormal noises from the water pump—if the impeller is damaged, water circulation stops. The most easily overlooked issue is improper coolant ratio: too much water can corrode metal, while too much antifreeze reduces cooling efficiency. It's best to follow the manufacturer's recommended ratio.

[TheoDella]

The biggest fear during long-distance hauling is the engine temperature gauge hitting the red zone, something I've experienced several times. Once on the highway, the temperature gauge suddenly maxed out, and upon inspection, it turned out the radiator cap's spring had failed, causing the coolant's boiling point to drop. Thermostat failures are also quite common—suddenly giving out on hot days, forcing me to pull over and wait for the engine to cool. Now, before every trip, I check the radiator fluid level and the tightness of the fan belt, and I always keep distilled water on hand for emergencies. When driving through mountainous areas in summer, I often have to stop midway to clean insect debris from the radiator.

[JoelFitz]

Our fleet has a standardized procedure for addressing high water temperature: clean the exterior of the radiator every three months to prevent clogging, and completely replace the coolant every two years. Cracks in the cooling system pipes often occur in areas with significant engine vibration, so daily checks for leaks are essential. Pay attention to pressure valve failures in hydraulic fans, as they can affect fan speed. Excessive engine load can also cause overheating, especially when climbing hills with heavy loads—downshifting to maintain RPM is crucial in such situations. Deteriorating temperature sensor accuracy can mislead drivers, so regular calibration of readings is necessary.