Thunderbird V8-4.6L VIN W (1997)
Power Steering Pump: Description and Operation
DESCRIPTION
The power steering system uses a belt-driven power steering pump to provide hydraulic pressure to the power rack and pinion steering gear. The
power rack and pinion steering gear uses integral valving that directs power steering pump flow and controls pressure as required to reduce
steering effort. The CIII power steering pump has the following features:
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It is a belt driven, vane-type, power steering pump.
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It is mounted directly to the engine block by four retaining bolts.
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An electronic variable orifice (EVO) control module.
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The electronic variable orifice (EVO) actuator is connected to the pump body to provide variable power assist.
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The electrical connector and casing are able to swivel. This is normal and does not indicate a loose actuator assembly.
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The power steering pump reservoir for the power steering oil is mounted to the LH engine coil bracket at the front of the engine.
NOTE: The power steering pump is serviced as an assembly. If any service is required, the entire power steering pump must be replaced. The
only exception is if the EVO actuator or connector on the power steering pump is found to be damaged; then replace the power steering control
valve actuator only.
ELECTRONIC VARIABLE ORIFICE (EVO)
The electronic variable orifice (EVO) system is designed to vary the flow from the power steering pump as a function of vehicle speed and
steering wheel rate of rotation, giving a form of variable assist.
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The system provides full power steering assist at low vehicle speed for light parking effort.
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The system provides minimum assist at high speed for good road feel and directional stability.
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Full assist is returned during evasive maneuvers.
