PEUGEOT/CITROËN 4007WQ PUMP ASSY VANE

The PUMP ASSY VANE is a belt-driven vane-type hydraulic pump that generates the continuous high-pressure fluid flow required by the hydraulic power steering rack and pinion gear to provide steering assistance proportional to road speed and steering load. The pump consists of a rotor with radially sliding vanes mounted eccentrically within a precision-machined cam ring housing; as the rotor turns, centrifugal force pushes the vanes outward against the cam ring wall, creating a series of sealed fluid chambers that expand on the intake side — drawing fluid from the reservoir through the suction port — and contract on the pressure side — compressing the fluid and forcing it through the high-pressure outlet port to the steering rack rotary valve at typically 80–160 bar. A flow control valve and pressure relief valve integral to the pump body regulate maximum outlet pressure and limit flow rate at high engine RPM, preventing over-pressure damage to the rack seals and maintaining a consistent steering feel across the engine's speed range. The pump shaft is supported on a sealed bearing and the shaft seal prevents fluid migration along the shaft to the belt drive. The pump is driven continuously at all times the engine runs, representing a constant parasitic load of 0.5–2.0 kW regardless of whether steering assistance is being used.

This unit — PEUGEOT/CITROËN 4007WQ — is manufactured to OEM-equivalent specifications: displacement per revolution, maximum rated output pressure, flow rate at rated speed, shaft diameter and pulley bolt circle, high-pressure outlet port and low-pressure return port thread sizes, reservoir mounting configuration or remote reservoir connection port size, and shaft seal type are matched to the original part. Supplied as a complete assembly ready for installation. Available wholesale from 35.06 USD, MOQ 20 pcs, production lead time 15-50 days.

Power steering pumps fail through vane tip wear from abrasive contamination in degraded or contaminated fluid causing progressive pressure output reduction, shaft seal failure allowing fluid to wet the accessory belt and causing belt slip and rapid belt deterioration, bearing failure producing a whining noise that is speed-proportional and independent of steering input, and pressure relief valve stiction causing erratic pressure delivery and steering feel variation. A pump that produces a whining noise only during steering manoeuvres has reduced output pressure rather than a bearing fault — the whine is cavitation from the pump trying to deliver more flow than its worn vanes can generate against the rack's demand; this is the most common pump failure presentation and confirms the pump requires replacement.