Big Dean MF85 Power Steering

The steering on the 85 is the same setup as the 88 and 90. The problem is usually the steering pump which is located on the right hand side of the transmission case. The oil from this pump is sent to a relief valve located in the clutch housing the valve is teed to the line routed to the oil filter and then to the steering valve. If the oil pressure exceeds approximately 1650 psi the relief valve dumps the excees oil back to the transmission. The return oil from the steering valve then goes to the oil cooler and finally to the pto valve. The pto vave regulates this oil to about 200 psi. There should be an oil sender that operates a lamp on the instrument panel that reads "don"t operate pto while light is on" (less than 150 psi). This is quite common if the tractor is idling, even on a good system. The pressure at the steering valve is going to be what ever effort it takes to turn the wheels, up to releif valve setting (1650 psi). The steering pump on an 85 does not operate the remote valves or the three point hitch. On a Super 90 it also operates the Multi-Power if equipped. To test the pump place a guage and service valve between the steering valve input line and the steering valve. Check the pressure before it goes into the steering valve by closing the service valve on test guage. Do not check the pressure after the oil cooler, because it will burst the cooler. The pto pressure can be checked by removing the pto lamp sender on the line along the right side of the fuel tank and inserting a 400-500 psi guage.

Tom Dold

Dold Implement
201 S. Main St.
PO Box 70
Howard, SD 57349 605-772-4541
[email protected]