If the engine consistently runs hot, consider checking these common culprits: Thermostat
When driving in mountainous terrain, manually downshift to keep your RPMs higher, which helps the water pump and fan work more effectively. eng motor home rj01228542 hot
Check the overflow or "surge" tank when the engine is cold. If it’s empty, you likely have a leak. Radiator Debris: If the engine consistently runs hot, consider checking
Secondary contributing factor: Low coolant level and degraded coolant condition reducing heat transfer efficiency. If the engine consistently runs hot
They had already tried the "easy" fixes. They pulled over at a rest stop in the high country, letting the beast idle. The radiator was full, and the overflow tank was topped off, but the engine was still derating, cutting power just when they needed it to climb. The Diagnosis