I have a d51 I just bought with a bad pump that runs the blade functions and the cooling fan, had 400 psi max, we replaced it now we have 3700 psi, but the cooling fan seems to spin way tp slow and the engine overheats, also the blade functions work normal one minute than thy slow to a snail past, wiggle the joystick and thy move fast again. Dealer mentioned maby some stuck solenoids under or around the seat?
Who replaced the pump? Was everything cleaned and flushed? Did the fan motor ever achieve max fan speed since pump swap.
We replaced the pump, cleaned the tank, ran a magnet on the button, was not anything in the tank, the dealer came out and we found some metal flakes in a few screens in the big valve block on the side. The fan works normal now, no over heating, but the blade will work normal than go really slow, if you jiggle the joystick it will go back to working fast, we took a valve out a second time and found a few more flakes in it.ite the valve the dealer told us the regulates the flow of the pump, we also switched the solenoid to make sure it was not that. Dose not do it when it's cold takes about 10 mins of running before it will do it. When it's slow it still has 3700 psi
Common thing is blade control lever is failing, lucky thing is it's half the price of the transmission control lever, also check your nitrogen cylinder has enough gas by lowering the blade with the engine shut off and key in position 1, new filters and new oil makes a big change in the drive experience.