Hydraulic PAS intermittent issue

Hydraulic PAS intermittent issue

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Discussion

jamieduff1981

Original Poster:

8,045 posts

147 months

Monday 18th August 2014
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Hi folks,

I have an issue with my S-Type which has been developing for a few months. In short, I have an intermittent PAS problem.

I have this little Jack Sparrow type character standing on my shoulder whispering "It's the steering rack valve" but before I sink that much in to the car I want some other opinions.

It's worst when the car is cold - i.e. when first started up after being parked for a while, so first thing in the morning and then again when I leave work to go home.

It doesn't really affect the car at small steering angles, so no issues when driving along at NSL. It's at carpark speeds mainly, or when negotiating T-junctions - that sort of thing.

The assistance will come and go as the lock is wound on, making it difficult to drive precisely. When it's time to straighten up, the rack will similarly lighten and stiffen - i.e. it will resist self-centering at some point during the lock-unwind. It's fairly repeatable now and will do it every drive.

Fluid levels are fine and there are no cavitation noises or anything like that. The car has done 80,000 miles and hasn't been crashed/bashed/otherwise inflicted trauma on the steering rack (beyond my repeated requests to turn-in to corners in an un-Jag-like fashion).

Your thoughts would be much appreciated!

natureboy8891

137 posts

178 months

Wednesday 20th August 2014
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Sounds like the UJ has gone.

S0 What

3,358 posts

179 months

Thursday 21st August 2014
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Could well be the U/J is seized and freeing off when hot? had success in the past boiling a seized U/J in a pan of grease (NOT done at home !! ) mainly A class mercs but done the same on the odd Mk3/4 fiesta as well, as long as there's no play in the U/J it works fine.
I do the same with my ratchets, makes em smooth as silk wink

PaulKemp

979 posts

152 months

Thursday 21st August 2014
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On my Mondeo it was the power steering pump
You can test this by taking the belt off and turn pump by hand, if its notchy it's the pp

jamieduff1981

Original Poster:

8,045 posts

147 months

Thursday 21st August 2014
quotequote all
Thanks chaps. I'll give that a try and see how I get on. Access to the UJ on S-Types looks pretty easy.

AW10

4,497 posts

256 months

Saturday 23rd August 2014
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I've had a few cars where at car park speeds with the engine at idle it was possible to "beat" the hydraulic assist by turning the wheel too fast. Is there any correlation to low engine speed?

CaptiV8ted

820 posts

218 months

Monday 25th August 2014
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Belts can slip sometimes if under tensioned, causing this issue. Have a feel of the belt and check the tensioner.