Information Information

The Power Assisted Steering System

My car came with power steering as standard and it was something that I had reservations about before taking the car for a test drive. As I have owned several Fiestas I was used to the manual steering which is by no means heavy - even at parking speeds. I assumed that power steering would be far too light but in fact it is perfectly weighted and the sharpness of the rack is greatly superior to the older manual racks.

There is much less vagueness with the PAS, which is something that could be very annoying at speed over uneven surfaces in Fiesta's equipped with a manual rack. When I fitted the 195 tyres the PAS came into its own even more, as at parking with these tyres in a manual car can prove to be an arm aching exercise!

PAS Fluid reservoir

The system is run from a pump mounted behind the alternator at the front of the engine, from here high pressure fluid runs in a metal tube up the front of the engine and over the cam cover (left), this connects to a flexible hose which runs to the rack. There is also a low pressure flexible return hose which runs to the header tank (spherical tank in the photo).

PAS Fluid cooler lines

There is a small oil cooler situated at the front of the radiator, inline with the air dam in the valance. This is a simple tube and fin cooler and ensures that the PAS fluid temperature remains within set limits, which keeps the fluid at a stable viscosity.

PAS Rack and lines

The rack itself is larger than the manual counterpart but fixes to the same two mounting points. The power rack has additional mounting brackets which fix to the bulkhead. These appear to be an after-thought possibly to fulfil some safety specification; they are not sturdy enough to perform any real function! The hubs are identical for power steering but special length lower arms are used.

The pump is equipped with an internal pressure relief valve. There is also a pressure sensor in the tubing on top of the cam cover; when the ECU detects a high oil pressure it restricts the RPM of the engine reducing the pressure.

© Mark Stewart, Thursday 15th June 2000
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