400SE Loss of power assistance

[B@man]

Driving home last night I was about to turn right and found I couldn't, faced with rearranging the front of the car I managed turn the wheel shortly after which the steering went lighter than normal and then settled down, I've checked the fluid level, bleed the system by turning from lock to lock a couple of time's and it seems OK this morning.

The steering also had a "moment" at the BBWF so I'm now a bit concerned about a complete failure. Is it more likley to be the pump or the rack ? and can they both be rebuilt as the car's SORN'd from the end of the month.

[ROOODBOY]

Was it raining at the time?

I've had this happen on a few cars in the wet, the belt slips for a moment, then it's fine again...

[B@man]

Hi

No but it had rained heavily a couple of hours earlier and everything was soaked so you could be right. The Alternator belt is tired too so I'll chuck another pair of belts on it.

[ed_crouch]

Yeh if the belt slips and you really have to hack the wheel to make it turn, you'll have twisted the quill shaft in the valve block right to the end stop which results in rather an exuberant return to service by the pas system when the belt regains traction - effectively by hauling the wheel round without power assistance creates a huge mechanical demand signal in the pas control valve and then the belt grips and the big demand signal results in lots of fluid flow and momentary over-assistance.

Well, that would be my estimation. hydraulic pas racks tend to work on a rotary valve and a quill shaft, sensing the twist of the quill.

No damage will have been done. Quill shafts are meant to twist it's what they do!

Edited by ed_crouch on Friday 17th September 18:38

[adam quantrill]

A drop of neat washing-up liquid on it will cut through any grease which gets slippy when wet, saving the hassle of changing the belt. There is adjustment too, on the PAS pump, to tension the belt.