This machine has a heater in the cab in the overhead console. I had the rad out to a shop to be cleaned. I proved the system flow by removing the upper rad hose and pushed all the coolant out the thermostat housing with a shop vac blower. It flew out no problem. The coolant wasn't dirty at all. Fan belt is tight. I removed the thermostat and tested it in boiling water. It opened. I left it out. I finally changed the water pump. The bearing wasn't as free as the new spareco pump but it didn't seem bad. The block was clean inside. No sludge. The new impeller fins were slanted same way as The original Massey pump. It still overheats. I'm stumped. What did I miss?