Flushing a power-steering system
This post mainly applies to the SE5 and 5A.
This problem can be quite alarming when it happens. The steering becomes lumpy and hard to turn. It feels as though the steering is passing through a series of notches. The problem is nearly always the steering column joints, but can also be a fault in a lower trunnion, top joint, or the steering rack.
To determine where the problem lies, jack the car up so that both front wheels are clear of the ground and support the car with axle stands under the chassis. Turn the key to take the steering lock off. Grab hold of a road wheel and swing it through the full range of travel, getting used to the feel of the lumpiness. At the same time, keep a finger on the track rod end to see if there is any play in it. If so, mark it for replacement.
Disconnect both track rod ends and move each road wheel in turn to see if the lumpiness is still there. If it is, then the fault is in the top joint or the lower trunnion, and you will need to strip down the vertical link assembly.
Test each track rod end in turn for stiffness, then pull and push the rod end to see if the lumpiness is still there. Assuming that it is, then the problem is either in the rack, or the column joint.
Slacken off the pinch bolt nut on the bottom column joint and remove the pinch bolt. Centralise the wheel. Undo for about 3/8", but do not completely remove, the four bolts securing the steering rack. Lever the rack forwards, and lever the bottom column joint back so that the column is disconnected from the rack. Test the rack by pulling and pushing the rod end.
Assuming that no fault is found in the rack itself, the problem is now in one of the column joints. Undo the top pinch bolt and remove the column joint from the steering column shaft. You can now test each universal joint in turn; I have found joints to be either stiff or loose in the past. The cure is replacement
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Flushing debris from the power steering system is something that few owners would do. The company who recondition the racks for me suggest that it should be done when fitting a reconditioned PAS rack to avoid contaminating the new rack with dirt remaining in the system.
It could also be carried out as part of routine maintenance to try and prolong the life of the rack and pump, or to assess whether deterioration in the rubber hoses and rack seals has occurred. The Scimitar system runs a relatively high pressure (600 psi) with no filtration, other than any natural settling-out of debris when the car has stood for a period of time.
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