The cooling system in a big rig plays a critical role in keeping the engine operating at safe temperatures under heavy loads and long driving hours. Because diesel engines generate significant heat, even a minor cooling system issue can quickly escalate into a major problem if ignored. Understanding the most common cooling system problems helps drivers and fleet operators take swift action to avoid costly repairs, downtime, and engine damage. At Billy Bob’s Repair & Tire, we provide expert big rig cooling system repair in the greater San Antonio, TX area. Here are four common big rig cooling system problems that should be addressed ASAP.

Coolant Leaks

Coolant leaks are one of the most urgent cooling system issues in big rigs. Leaks can occur at hoses, radiators, or gaskets and may start small before rapidly worsening. Even a slow leak reduces coolant levels, limiting the system’s ability to regulate engine temperature. If left unchecked, coolant loss can cause overheating, warped components, and severe engine damage. Addressing leaks immediately helps maintain proper cooling and protects critical engine parts.

Clogged or Failing Radiator

The radiator is responsible for dissipating heat from the coolant as air passes through its fins. Over time, dirt, debris, bugs, and road grime can clog the radiator, restricting airflow and reducing cooling efficiency. Internal buildup from contaminated coolant can also block coolant passages. A clogged or failing radiator causes rising engine temperatures and should be cleaned or repaired promptly to restore proper heat transfer.

Faulty Thermostat

The thermostat regulates coolant flow by opening and closing based on engine temperature. When it sticks closed, coolant cannot circulate properly, leading to rapid overheating. A malfunctioning thermostat can create inconsistent temperature readings and should be replaced without delay to ensure stable engine operation.

Failing Water Pump

The water pump is responsible for circulating coolant throughout the engine and radiator. When it begins to fail, coolant flow is reduced or stopped entirely, causing temperatures to rise quickly. Common signs include coolant leaks near the pump and unusual noises. Because the water pump is essential to the cooling system, any signs of failure should be addressed as soon as possible.

24/7 Mobile Big Rig Repair in San Antonio, TX

For roadside semi truck repair in San Antonio and the surrounding area, contact Billy Bob’s Repair & Tire at (210) 796-3891. Our team also provides roadside big rig repair in greater Austin, TX. Feel free to give us a call and we’ll arrive ASAP to get you back on the road!