1985 Autocar: we work on any truck
If it runs diesel and needs help, we'll show up. Age is not a barrier: classic, vintage, or modern.
Cooling & Radiator Repair
Truck Cooling System & Radiator Repair in Charleston, SC
Temperature gauge creeping up, coolant disappearing, or a fan that never shuts off? We track down cooling problems on-site so the part that gets replaced is the one that actually failed.
- Overheating, coolant loss, radiators, water pumps, fan drives, EGR coolers
- Pressure and coolant testing at the truck before parts get ordered
- Charleston, North Charleston, Summerville, Goose Creek, Mount Pleasant
Cooling Problems We Diagnose
What's behind a hot engine or an empty surge tank
Running hot
Temps that climb at idle, in traffic or on a slow pull, from a stuck thermostat, a lazy fan or a blocked stack.
Coolant loss
Leaks at hoses, clamps, radiator tanks and the water pump, or internal loss through an EGR cooler or head gasket.
Radiator & cooling stack
Radiator, charge air cooler and A/C condenser sit stacked together. Packed fins cut airflow even when the pump is fine.
Fan drive & water pump
Air-actuated and viscous fan clutches, weeping or noisy water pumps, and worn belts and pulleys.
Why Test Before Replacing
A hot engine isn't always a bad radiator
A radiator gets swapped and the truck still runs hot, because the real problem was a fan clutch that never locked up or a stuck thermostat. Coolant gets topped off for weeks while an EGR cooler leaks internally. On a Class 8 truck the coolant also carries heat from the transmission and engine oil coolers, and the radiator shares its airflow with the charge air cooler and A/C condenser, so one weak link can look like several.
We work through the system at the truck: temperature and fan data, a cold pressure test, the stack, and the coolant itself. You get a clear answer on what failed before a radiator or pump gets ordered.
Why operators call us
- Mobile service where the truck is sitting
- Testing before parts replacement
- Clear written findings and next steps
- Commercial diesel and fleet-focused support
- 24/7 Charleston-area availability
Our Cooling System Process
How we find a cooling fault on-site
1. Codes and temp data
Coolant temperature, fan command and active codes show when it gets hot and whether the fan is told to run.
2. Airflow and fan check
We confirm the fan clutch engages (air supply on on/off clutches, lock-up on viscous ones) and check the stack for debris.
3. Cold pressure test
Pressurizing the system engine-off finds leaks at hoses, tank seams, thermostat housing, water pump, heater core or cap.
4. Pump, thermostat, belts
Coolant or oil at the pump weep hole tells us which seal failed. Bearing noise, belt drive and thermostat opening get checked too.
5. Internal leak test
With no puddle, we test the coolant for combustion gas and watch exhaust and oil to separate an EGR cooler from a head gasket.
6. Coolant condition
Conventional coolant gets a nitrite strip test for liner protection, with additive if it is low. Extended-life coolant gets a condition check.
Repairs At The Truck
What we fix on the spot and what needs a part
Many cooling repairs are finished on the first visit: split or soft hoses, worm-gear clamps loosened by heat cycling, a thermostat and seal, a belt or tensioner, a fan clutch that is not getting air, or a packed cooling stack.
Radiators, water pumps, fan clutch assemblies and EGR coolers are specific to the engine and chassis. We confirm the failure, get the correct part for your unit, and install it where the truck sits. A leaking charge air cooler causes low power and black smoke, so we pressure test it while we are there. On many late-model engines coolant also heats the DEF tank, so a cooling fault can surface as an aftertreatment warning.
What to text us
- Year, make, engine and unit number (or VIN)
- Where the truck is parked or broke down
- When it runs hot: idle, traffic, climbing or highway
- Photos of the gauge, any leak and the fan area
- Any white smoke, coolant smell or active codes
Truck overheating in the Charleston area?
Call or text Lowcountry Diagnostics and we'll find the cooling fault at the truck.
Common truck cooling system questions
Why does my truck run hot at idle but cool down on the highway?
That pattern usually points to airflow, not coolant flow. At idle and in slow traffic the fan does most of the work, so a fan clutch that is not engaging (an air-actuated clutch that is not getting air, or a viscous clutch that has lost its fluid) or a cooling stack packed with debris shows up there first. We check both before anyone condemns the radiator or water pump.
I keep adding coolant but can't find a leak. What's going on?
Coolant that disappears without a puddle is often going inside the engine. A cracked EGR cooler usually shows as white, sweet-smelling exhaust at start-up or under load while the oil stays clean. A head gasket is more likely to push bubbles into the overflow tank or contaminate the oil. We pressure test, check the coolant for combustion gas, and watch the exhaust and the oil to tell them apart.
Can you fix a radiator or water pump where the truck is parked?
Yes. All of our work is done on-site at your yard, jobsite or roadside. Hoses, clamps, thermostats and belts are often handled on the first visit. For a radiator, water pump or EGR cooler we confirm the failure, get the correct part for your unit, then install it at the truck.
What should I do if the temperature gauge is climbing?
Pull over when it is safe and let the engine cool. Do not open the radiator or surge tank cap while the system is hot and under pressure. Then text (843) 310-0995 with your location, a photo of the gauge and any warning lights, and whether you see steam, a puddle or white smoke.
Request Cooling System Repair
Tell us where the truck is and what the temperature gauge is doing. For a truck that is overheating now or stranded, calling or texting is fastest.
Overheating right now? Call or text (843) 310-0995.
Recent Repair Photos
A look at the repairs we make
Real field photos from Lowcountry Diagnostics, from engine diagnostics and electrical to hydraulic, HVAC, and heavy-duty truck service, handled on-site across the Charleston area.
Reviews
What Charleston truck owners and fleets say
“These gentlemen are very helpful and methodical about the way they go about diagnosing your truck I recommend them”
“He stayed on top of troubleshooting and never stopped until everything was fixed.”