Recon PAS Pump Failure Twice! in 3 years

[jwpalfrey]

Hi All,

Just wondering if anyone has any experience on this, I've got a 1996 XK8 4.0 approaching 130k miles now. Since I've owned it it will now be needing it's third PAS pump which seem ludicrious! Especially since I bought it on 122k miles.

The first pump failed a few years ago, the bearing went and thus so did the seal, so I got a replacement recon unit from The Steering Specialists who trade on eBay and supply a recon unit for ~£125 on an exchange basis.

They offer an 18 month warranty and they honoured this when the pump failed again (same issue - bearing failure) after approx 17 months use, I was right at the end of the warranty, but still in date so they sent me another pump, and all was ok.

The car has just gone in for a front subframe overhaul and the specialist advised me that this pump was "noisy" and on it's way out.

Given I only changed this one no more than two years ago and 4000 miles maximum it seems very short life again.

I've emailled them to see what they say, perhaps dodgy batch of bearings etc, I don't know. I'm not expecting anything from it but an explanation of sorts would be nice.

Has anyone else experienced similar?

The specialist I use has never seen PAS failure and never changed one in 20 years of working on Jag's, he always uses genuine parts where available.

Now I'm thinking is something on my car causing premature pump failure? Is the belt tensioner too tight? Not sure how, it's a pre-tensioned arm.

I use the correct ATF DEX III fluid.

The only thing I can think of is that I've fitted the speed sensor switch, which disables the bosch servotronic and puts the PAS at it's lowest level of assistance if switched off for improved steering feel, which may run the pump at a higher pressure as less assistance is used at the rack, but theoretically this is no different to driving it above 50mph or so as in higher speed states the servotronic reverts to the same low level of assistance.

Anyway any advice or ideas appreciated, I've now sourced a genuine used item which I hope will last longer than 18-24months.

[mike020150]

Have you tried measuring the pressures in the system? The pump is capable of producing 110 bar so you'd need an appropriate gauge but it might give you a clue whether your mod is causing the issue. Mike.

[jwpalfrey]

I haven't tried measuring the pressure, but as you say I'd need some specialist equipment for that.

I do have a spare rack, I assume that the valve controlling the assistance and thus the pressure is on the rack?

[mike020150]

It looks as if you have two choices. Since the only way to determine if your mod is causing the problem would be to measure the pressures generated, without a suitable gauge you could get someone to measure them for you. Alternatively, revert the car to standard and simply see if that cures the problem. Mike.