Pump Test

This procedure tests power steering system on vehicle:

• With engine off, inspect fluid level. Fill if needed.
• Check belt tension. Adjust if needed.
• Disconnect pressure hose and connect spare pressure hose to pump fitting.
• Connect spare hose to gauge side of Hydraulic Pump Pressure Tester and Tube Assembly Adapters (C-3309E and L-4601). Ensure valve on tool is on outlet side of gauge. New fittings are required on hydraulic pump pressure tester to adapt to new "O" ring-type hose tube ends.
• Open hand valve on hydraulic pump pressure.
• Insert thermometer in fluid reservoir. Start engine. Turn steering wheel from lock-to-lock to warm fluid to between 150-170°F (66-77°C).
• With engine idling and gauge valve open, initial pressure should be between 30-50 psi (207-345 kPa). If pressure exceeds 100 psi (690 kPa), check hoses for crimps and/or restricted hoses.
• Close and open gauge valve completely 3 times for 5 seconds and record highest pressure reached.
• If recorded pressures are within specifications and range of readings is within 50 psi (345 kPa), pump is operating properly.
• If pressure is high but does NOT repeat within 50 psi (345 kPa), flow control valve in pump is sticking. On Saginaw pump, control valve can be removed and cleaned. Replace "ZF" pump.
• If pressures recorded are constant but low, clean or replace pressure relief valve and flow control assembly on Saginaw pump. If pressures are still low, replace pump. Replace "ZF" pump.
• If pump checks okay, leave gauge open and turn wheel from lock-to-lock with engine idling. Record highest pressure attained at each lock. If pressure cannot be built up at either lock, the steering gear is leaking internally. Replace steering gear.