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March 22, 2024

Why Is My Truck Overheating? A Guide For Truckers

Why Is My Truck Overheating? A Guide For Truckers

As the winter weather starts to fade, and the summer heat gets closer, truck drivers and fleet managers must take a proactive stance on coolant system maintenance if they’re to avoid overheating issues. For those interested in learning how coolant systems work, and how you can prevent them from failing, you’ve come to the right place. 

We here at The Service Company are dedicated to keeping your medium-duty and heavy-duty trucks running smoothly all through the year. To schedule an appointment for service, contact us today. 

Coolant Systems: What Are They? 

Before we jump into how they may fail, and how they need to be maintained, let’s chat about how they actually work. For those who already know how these systems work, feel free to jump into the next portion of this article. 

First and foremost, the overall goal of your truck’s coolant system is to simply collect the excess heat generated by your engine, and remove it. This is generally referred to as a heat transfer process, and there are several components acting in unison to accomplish this task. 

The process, in brief summary, is the flow of liquid coolant, propelled through your system by your water pump. The coolant absorbs radiant heat from your engine and flows into your radiator, where it comes into contact with cold air funnelled in by your cooling fan and fan clutch. When it meets the cold air, the heat is dissipated, and the coolant returns to your engine where it will collect more radiant heat and repeat the process. Let’s dive into each component a little further, shall we? 

  • Liquid Coolant - Liquid coolant is a mixture of antifreeze and water and is highly heat-absorbent. Generally, this liquid can last a hundred thousand miles or more before it needs to be flushed and replaced. 
  • Water Pump - This component is powered by your serpentine belt, and is what pushes the liquid coolant throughout your system. This ensures a continuous flow of coolant to maintain optimal operating temperatures and prevent overheating.
  • Radiator - Has a series of fins and channels that force hot coolant to come in contact with cold outside air. This is where the heat dissipation takes place. 
  • Cooling Fan - This fan draws air from outside your engine bay into your radiator. This component is controlled by your fan clutch. 
  • Fan Clutch - Your fan clutch activates and deactivates your cooling fan. For example, when driving at a high rate of speed, you will have plenty of airflow, so your fan clutch will disable your cooling fan. This is a thermodynamic component. 

What’s Making My Engine Overheat? 

Your truck’s engine can overheat for a variety of reasons, so being knowledgeable about these points of failure can save you a lot of time and hassle in the long run. The most common culprits are a malfunctioning fan clutch, a plugged radiator, and leaking coolant. 

Malfunctioning Fan Clutch Explained

Without a properly functioning fan clutch, your cooling fan will not engage or disengage as necessary. Here are a few fan clutch failure scenarios explained:

  • Stuck Open or Not Engaging: If the fan clutch is stuck in the open position or fails to engage, the fan won't spin at the necessary speed to cool the engine effectively. This situation means less air is pulled through the radiator, reducing its ability to dissipate heat, leading to overheating, especially when the truck is under heavy load or operating in hot weather.
  • Stuck Closed or Always Engaged: Conversely, if the fan clutch is stuck in the closed position, the fan will always be engaged, spinning at maximum speed regardless of the engine temperature. While this might seem beneficial for cooling, it's inefficient and can lead to other problems, such as excessive noise, reduced fuel economy, and unnecessary wear on the fan clutch itself. However, this condition is less likely to cause overheating compared to a clutch that fails to engage.
  • Seized Bearing: The fan clutch has a bearing that allows it to spin. If this bearing seizes, the fan can stop spinning altogether. This failure mode effectively turns the fan into a stationary object, severely compromising the cooling system's ability to manage engine heat.

Plugged Radiator Explained

If your radiator doesn’t allow for coolant to flow through it, there won’t be any way for heat to be dissipated. This leads to overheating, and in severe cases, damage to other components like your water pump and coolant hose infrastructure. Here are a few plugged radiator scenarios explained: 

  • Reduced Coolant Flow: The radiator is responsible for dissipating heat from the coolant that flows through it. When the radiator gets plugged with debris, rust, or sediment, the flow of coolant is restricted. This reduction in flow prevents the coolant from adequately transferring heat away from the engine to the radiator, where it can be cooled by airflow.
  • Decreased Heat Dissipation: The fins and tubes within the radiator are designed to maximize surface area for heat exchange between the coolant and the air passing through. A clog can block these paths, reducing the radiator's ability to dissipate heat. When the heat exchange is compromised, the coolant returns to the engine at a higher temperature, diminishing the cooling system's effectiveness.
  • Overpressure in the Cooling System: A clogged radiator can cause pressure to build up in the cooling system. This overpressure can lead to failures in other cooling system components, such as hoses, the water pump, and the radiator itself, which may crack or leak under increased stress.

Leaking Coolant Explained

The cooling system is designed to be a closed loop, circulating coolant to transfer heat away from the engine. When there's a leak, the system can't maintain the proper level of coolant, and several issues can arise as a result:

  • Reduced Coolant Volume: A leak in the cooling system reduces the amount of coolant available to absorb and dissipate heat from the engine. With less coolant circulating, the system can't efficiently manage engine temperatures, leading to overheating.
  • Air in the System: Coolant leaks can introduce air into the cooling system. Air pockets, or "airlocks," can form and disrupt the flow of coolant, preventing it from reaching critical areas of the engine. This disruption in circulation reduces the cooling system's effectiveness and can cause hot spots that lead to overheating.
  • Increased Coolant Concentration: If a leak causes significant coolant loss and the driver continues to add water without the proper concentration of coolant, the boiling point of the mixture may decrease, and its ability to prevent corrosion and freezing may be compromised. This diluted mixture can boil at lower temperatures under engine load, leading to overheating.

Contact Our Shop Today

Understanding the intricacies of how coolant systems function, recognizing the common culprits behind overheating, and being proactive in addressing these issues are crucial steps in ensuring your truck remains operational and efficient. 

The Service Company stands at the forefront of providing expert service and maintenance for medium-duty and heavy-duty trucks. With our comprehensive knowledge of coolant systems, including the handling of malfunctioning fan clutches, plugged radiators, and coolant leaks, we are the go-to shop for truckers facing overheating issues. 

Our commitment to keeping your trucks running smoothly throughout the year is unwavering. Don't let overheating setbacks keep you off the road. Contact The Service Company today to schedule your appointment and ensure your truck is equipped and ready to tackle the challenges of the road ahead.