Power steering on/off/on/off

[Eddleston]

Hi all.
I've put a xsara vts rack in my 306 and when I'm going round a constant corner, eg a long roundabout, it feels like the power steering is on then gives up for about a second, then comes back on again for about a second. 
This keeps happening but it's very much constant in the time between it feeling like it kicks out and back in again. And then out again. Almost like someone setting an electric pulse on it every second or just over. 
Anyone had this? 
I thought track rod ends but it would be all over the place if it was them.

[zx_volcane]

sounds like the pas system is loosing pressure briefly

[powerandtorque]

I had the same with a VTS rack but I never did work out what was wrong - it was something related to the rack itself though, as I put another one in and the issue vanished and never reappeared in what must have been 40-50k miles.

In my case the TRE's were new, track rods themselves in VGC, no play in the NS rack bush and the fluid was new. My best guess is that the hydraulic valve in the rack was faulty in some way or had loads of play in it, hence getting a strange surging sensation through the steering when it was lightly loaded on a continuous radius turn.

Someone like Rippthrough will likely know the exact cause.

[Mattcheese31]

Checked to see if fluid is low?

[Eddleston]

I had the same with a VTS rack but I never did work out what was wrong - it was something related to the rack itself though, as I put another one in and the issue vanished and never reappeared in what must have been 40-50k miles.

In my case the TRE's were new, track rods themselves in VGC, no play in the NS rack bush and the fluid was new.  My best guess is that the hydraulic valve in the rack was faulty in some way or had loads of play in it, hence getting a strange surging sensation through the steering when it was lightly loaded on a continuous radius turn.

Someone like Rippthrough will likely know the exact cause.

Oh god, I do NOT fancy getting that out now the engine is all back in and running! 

But yes, the fluid is up to the right level. Unfortunately this doesn't sound like quite such an easy fix any more. 

[pug306driver]

Are parts available for the rack, an exploded view may be ?

Also a pressure relief valve in the pump or system somewhere, may be a broken spring in relation to this valve or similar in rack ?

does it only happen on held turns ?

I presume the system is fully bled ? and all unions tight ?

[Paul_13]

I remember driving that when it was doing it, very strange indeed. Nothing to do with fluid level, like you say something to do with the rack/ram

I had the same with a VTS rack but I never did work out what was wrong - it was something related to the rack itself though, as I put another one in and the issue vanished and never reappeared in what must have been 40-50k miles.

In my case the TRE's were new, track rods themselves in VGC, no play in the NS rack bush and the fluid was new. My best guess is that the hydraulic valve in the rack was faulty in some way or had loads of play in it, hence getting a strange surging sensation through the steering when it was lightly loaded on a continuous radius turn.

Someone like Rippthrough will likely know the exact cause.

[Poodle]

Did you also swap the uj on the column? If that's getting tight it could cause that feeling.

[powerandtorque]

Can't speak for the OP, but in my case UJ was fine - it was as if the assistance completely vanishes and then comes back, repeating every few seconds, even through you were barely (if at all) moving the wheel on a constant radius turn like a roundabout. That's why I guessed it's an internal valving fault of some kind on the rack, given that the pump, UJ etc were fine on the rack before and after.

In my experience UJ issues tends to show itself with the steering either being heavy all the time, notchy as you wind on lock or having play particularly noticeable around straight ahead, depending on exactly what's wrong with it.

[Eddleston]

Did you also swap the uj on the column? If that's getting tight it could cause that feeling.

I honestly can't remember if I kept the rallye one on left the VTs one on the rack.

[Poodle]

Hmmm, re-reading the original post i'd say powerandtorque is absolutely right, that doesn't sound the same as a sticky uj. Sorry, skim read before and misunderstood.

[bashbarnard]

Its the pump. This doesn't just happen on vts racks berlingo and partner vans are sods for it. Last time we put a pump on one cured it.

[Paul_13]

I think you missed what Powerandtorque said.
He changed just the rack, not the pump and the problem was solved

[Eddleston]

Well doing the pump is considerably easier than the rack! worth a try either way. 

I'll be back at my parents for Christmas so might see if changing the pumps over does anything.