Power Steering Pumps: Hydraulic Assist on Older Cars

Power-steering pumps generate the hydraulic pressure that assists the driver’s steering effort on cars with hydraulic-assist PAS. The pump is belt-driven from the engine and circulates fluid through the steering rack and back to a reservoir. Modern electric power steering (EPS) eliminates the pump entirely, but most cars on UK roads still use hydraulic-assist.

How they fail

Internal vane wear — the pump can no longer build full pressure. Steering becomes heavy at parking speeds. Often progressive over months.

Seal leakage — fluid leaks from the pump shaft seal. Symptoms: drips of red or amber fluid below the engine bay, fluid level dropping in the reservoir.

Bearing failure — the pump shaft develops play, often producing a whine on steering input. Eventually seizes.

Replace as a system

Always change the fluid with a new pump (contaminated fluid would shorten the new pump’s life). Always check the high-pressure hose from pump to rack — a worn pump often correlates with a worn hose. On some cars (particularly older Mercedes), check the in-line PAS filter if fitted.

Brand

ZF, TRW, Bosch supply OE-equivalent pumps for most European applications. Hitachi and Showa for Japanese. The reman parts from these brands are full-OE-specification.

Find power steering pumps for your car on the Power Steering Pump collection.