If it primarily uses a belt driven fan(water pump), I would think about changing clutch unit. I only say that because I drove a service truck for a bus company(old ranger 4x4 plow turd), that would run very hot in below zero weather on a 10 mile highway trip with blade on. Tried running blade at many angles and heights, still got hot fast. Put a new clutch on the stock fan, and not a problem since.