Hills and humidity are what test a cooling system around here.
A loaded truck climbing I-75 toward Jellico, working up onto the Cumberland Plateau on I-40 west, or crawling through the Pigeon River Gorge is pulling hard for miles with little airflow. Stack that on a humid July afternoon in the 90s, or a long idle in I-640 traffic with the A/C on, and a cooling system that barely kept up in spring can let go.
Overheating is one of the fastest ways to turn a cheap repair into an expensive one. A hose that splits can warp a head or damage a liner if the driver keeps pushing. Caught early, the problem is usually a hose, a clamp, a belt, or a fan clutch — not the engine.
What’s included with our Cooling System & Radiator Repair
- Radiator and heater hose replacement
- Clamp and coolant pipe leaks
- Fan and serpentine belts, tensioners, and idler pulleys
- Fan clutch diagnosis — engaging when it should, and not dragging when it shouldn’t
- Fan clutch air solenoid and air line problems
- Water pump replacement on many engines, depending on access
- Thermostat replacement
- Coolant temperature and coolant level sensor faults
- Surge tank and pressure cap problems
- Pressure testing to find leaks
- Topping off with the right coolant for your engine
- Checking radiator and charge air cooler fins for leaves, bugs, and debris
What needs a shop instead
- Radiator replacement on trucks where it means pulling the hood and front-end parts — often a shop job
- Radiator core repair and recoring
- Head gasket, liner, or oil cooler failures that put coolant in the oil or oil in the coolant
- EGR cooler replacement on engines where it needs major teardown
Milky oil on the dipstick or oil floating in the coolant reservoir means don’t run the engine. That points to an internal leak that needs a shop.
Repair it where it sits, or tow it?
Hoses, belts, clamps, thermostats, fan clutches, and sensors are routine mobile repairs. If the engine ran hot briefly and was shut down quickly, replacing the failed part and refilling coolant often has the truck back on the road the same day.
A tow is smarter if the engine ran hot for a long time, shows signs of internal damage, or lost its coolant and kept going. Never open a hot radiator cap or surge tank — the coolant is under pressure and can cause severe burns. Let it cool before anyone touches it.
Have this ready when you call
A few details up front help the mechanic load the right parts and tools and get it done in one trip.
- How hot the gauge got and how long the truck ran that way
- Whether you see steam, coolant on the ground, or a burst hose
- Whether a belt broke or the fan isn’t turning
- Coolant warning lamps or fault codes
- Whether the engine is shut off now
Makes & engines we work on
- Freightliner
- Peterbilt
- Kenworth
- Volvo
- Mack
- International
- Western Star
Class 6 through Class 8 trucks, including engines from Cummins, Detroit Diesel, PACCAR, Volvo, Mack, Navistar, and Caterpillar.
Cooling System & Radiator Repair around Knoxville & East Tennessee
Overheating calls around Knoxville peak in summer and on the grades: I-75 north of Caryville, I-40 west past Kingston toward the plateau, and I-40 east toward the gorge. We also see them in stop-and-go traffic on I-640 and Alcoa Highway, and from trucks idling for hours at docks.
Highways we cover
Towns we cover
- Knoxville
- Farragut
- Maryville & Alcoa
- Oak Ridge
- Clinton
- Lenoir City & Loudon
- Sevierville & Pigeon Forge
- Morristown
Cooling System & Radiator Repair: common questions
My truck is overheating. What first?
Get off the road safely, take the load off the engine, and shut it down if the gauge is in the red or a stop-engine lamp is on. Don’t open the radiator cap while it’s hot. Then call.
Can I add water to get off the interstate?
In an emergency, water can get you to an exit, but it dilutes freeze and corrosion protection — a real risk here once winter comes. Have it drained or corrected with the proper coolant soon.
Why does it only run hot on hills?
A long climb needs full cooling capacity at low road speed. A partly plugged radiator, a weak water pump, a sticking thermostat, or a fan clutch that isn’t fully engaging may keep up on flat ground but fall behind on a grade.
Why does it overheat in traffic but not at highway speed?
At low speed there’s no ram air through the radiator, so the fan does all the work. A fan clutch that isn’t fully engaging, or a radiator packed with debris, is a common cause.
Does coolant type matter?
Yes. Mixing incompatible coolants can cause problems. Tell dispatch your engine make so the right coolant is used.
How do I know if overheating hurt the engine?
Warning signs include coolant in the oil, oil in the coolant, white exhaust smoke with a sweet smell, or lost compression. A mechanic can pressure test and check for these before you run it again.