How hot is too hot? Trip report on first tow...

[CStansbury]

I returned yesterday evening from WV towing a 16' trailer with my 404 Unimog on it. We came across some pretty good mountain passes on the way here (pales in comparison to you Rockies folk I'm sure). The trailer and Mog weigh about 8600 lbs. The steepest grade slowed me down to around 55mph in 5th and then 60 in 4th. When in 5th or 4th, the EGTs hung right around 1200-1250 with the pedal matted. After several minutes like that, the factory engine temp gauge would climb as high as 220 and stay there until I crested the hill and then cool off pretty quickly coasting down the other side.

Questions are: Am I pushing the temps up by staying in 5th too long and keeping the rpm's low? Would running the big hills in 4th from the bottom help by spinning the rpm's up and moving more air/coolant? Am I doing any harm by running it that hot?

I was very pleased with the Optix gauges on the trip. They seemed to respond very quickly to temp/boost changes.

I'm guessing with temps maxing out at 1250 and 31 psi matted pulling 8600, that I have 215 injectors and a boost fitting with a stock plate. It'll work good for now. I do plan on getting a bigger trailer, about a 20' gooseneck, so that should push my weight up to about 9600. I'll prolly be looking for more power then