Wasn't there some problems with reman engines and water pump impellers, overheating, engine failures, and the like?
I think Mike Chan had one of these, where the impeller fell off the water pump.
And I agree with the high engine temps being the fan issue, I think I have seen the fan clutch come on between 214-218 degrees EOT.
We're right around 0C/32F here, and driving a truck with 4.30 gears in MLP range '3' at 3200rpm for about 5 minutes only got me ~196 ECT and ~210-213 EOT, I didn't even hear the fan come on.