I have Model GC40K forkilft that is overheating. The waterpump, thermostat and head sensor have been replaced. The radiator is good. The tech that has been working on this forklift has told me that only thing that can be overheating it now is the operator is driving it too hard. It is causing the transmission/hydraulic fluid to overheat and that is what is shutting it down. The hydraulic cooler is has been checked also. The engine in this unit is the V6 Vortec.

Any thoughts would be greatly appreciated.