This is a good idea. Just found it. I never read the stuff in bold print at top of forums;
2000 Itasca Horizon DP 36'
300 Cat
6 speed Allison
towing 4dr. 4wd Tracker
Heading west over the Bighorns in Wyoming from Yellowstone through Cody. Long pull to top of pass and the engine starts overheating. Pull over to check coolant and it is fine and full. Engine cools down within normal range almost immediately. In the next 8-12 miles had to pull over to cool 5-6 times.
Figured the altitude and toad causing the heating. Not further problems until some long hills in South Dakota when the temp indicator went up but no warning buzzer.
No further problems until August coming out of Alabama and heat went up. Same thing in NC crossing mountain and buzzere went off. Engine cooled down very quickly.
This coach had made a trip from Georgia to Las Vegas the previous year with no problems at all.
Resolution:
RV.net member PM'd after hearing of the problem and said he thought the radiator was partially blocked. Trip to a quarter carwash and a handfull of change and a tremendous amount of dirt and oily crud washed out of the radiator. Turns out Freightliner left the puke pipe from the crankcase breaker too short and it dumps the oily smoke and fumes on the radiator core. Dust and road debris collects on that and causes air flow restriction.
Cost: frayed nerves for a few hours and about 4 dollars and 20 minutes with high pressure spray and degreaser.