Towing in Florida heat: a cooling strategy for Cummins trucks
Ninety-five degrees, eighty percent humidity, and a loaded trailer. Where the heat actually comes from and how to get rid of it.
Florida towing has a specific character. It is not the altitude and long grades of the Rockies. It is sustained ambient heat, humidity that reduces air density, and traffic that keeps you off the throttle and then back on it. Heat accumulates differently.
Three temperatures you have to watch
- Coolant temperature — the one the factory gauge shows you, and the least sensitive.
- Exhaust gas temperature — the leading indicator of how hard the engine is working.
- Transmission converter-out temperature — the one that decides whether the 68RFE survives.
Handling heat on the road
The instinct is to hold speed at any cost. On a stock tune that usually works. On a tuned truck pulling a heavy trailer in July, backing out of the throttle three miles per hour can drop EGT by well over a hundred degrees and stabilize transmission temperature.
| Reading | Action |
|---|---|
| EGT above 1,300°F sustained | Reduce speed, downshift to raise RPM and move more air |
| Trans temp climbing past 220°F | Lock the converter out of hunting by selecting a gear, reduce load |
| Coolant climbing in stop-and-go | Turn the A/C to recirculate, get air moving through the stack |
Hardware that actually helps
An upgraded intercooler lowers charge-air temperature, which lowers combustion temperature and EGT. A larger transmission cooler lowers converter-out temperature. An unrestricted exhaust lowers drive pressure and heat. These are the three that move the needle on a towing truck.
Marcus Reyes
Lead Technician
Part of the Sunstate Diesel team in Orlando, Florida. We work on RAM/Cummins trucks daily and write these notes from what we actually see on the lift.
