Running Hot!

ajriding wrote:
I had a 5.9 with a truck camper and trailer climbing the Rockies and temps stayed level. On big climbs temps would rise, then the thermostat would open, then cool back to high 180's, then close and rise into 190's and cycle back and forth (I had a quality temp gauge so could see this).

I never saw temps go high.

I suspect other issues,
A bad radiator - old and partly clogged- a mechanic shop can look at it with a temp gun and see if there is any clogs.
A bad fan clutch (slower speed climbing might require the fan to run)
A bad thermostat
Is the fan shroud intact and directing air correctly?
Nothing blocking the radiator?

Nothing untoward underneath. Fan shroud completely intact. New coolant last year. Don’t know if the rad is plugged, but like I said the unit only has 52,000kms on it so would struggle to understand why the rad would be in trouble.

I’m going to try and take it to a shop and steam it out. I cannot get under the bed / closet without a cutting torch at this point. Tried pry bars and hammers and the bed compartment is too tight to take apart.