Yesterday while driving to flagstaff, AZ, a 5 hour trip I've done 3 times this year already, my engine temp was going WAY up into the red and my coolant light and alarm was coming on while going up some of the larger hills along the route. As soon as I let off the gas the temp would drop and the alarm would go off. Once the incline leveled off the temp would drop all the way back down to the "cold" and everything would be fine. I'd hit another hill and the temp would rise back up again. I found myself doing hills at 35 MPH just to keep the temp under control.
I called the local Camping World and they said, "This is normal for Diesel engines. After a night of sitting, I opened the radiator cap and coolant poured out on me. So clearly it's full. I've put almost 9000 miles on this RV since we bought it and been up and down all kinds of mountains and hills. I've never had this happen before.
IS this normal? What else should I look at?
2000 Forest River Reflections 327s DP
Toad = 2009 VW Tiguan.
Coupla bikes, coupla dogs, coupla 30-somethings wishing they were retired.