Xantia heavy steering - hp?

xantiadave · Post by **xantiadave** » 30 Apr 2007, 09:30

Hi all,

I have noticed that the steering on my 1998 2.1 TD Xantia (124,000 miles)has become heavy. I suspect this has been happening gradually, but was made obvious on return to Dublin after driving a C2 on holiday in canaries last week. The brakes also feel less powerful. Last oil change 2 months ago, I noticed there was a slight leakage of LHM accumulating on bottom of alternator, but didn't bother to trace it back.

Six months (~6000 miles) ago I put on a new auxiliary drive belt, but the auto-tensioner had broken so I tightened it according to 'thumb test' referred to in this forum and Haynes manual.

Questions:

1) Is it almost certainly the hydraulic pump causing this problem?

2) Is it possible I damaged the hydraulic pump bearings to cause this problem by over-tightening belt, or is it it more likely to be old-age pump failure? (Have owned car for over 2 years, and suspect pump is on original).

3) Is it usual for these pumps to fail gradually? Is it safe to drive the car a few hundred more miles before replacing the pump?

Have busy week ahead, involving fair bit of driving, and would like to know how urgently I need to fix this.

Any advice appreciated!

Dave.

slim123 · Post by **slim123** » 30 Apr 2007, 14:25

Ahh, so many questions!!

1/ Is it almost certainly the hydraulic pump causing this problem?
Probabally but you just cannot be certain without testing.

2/ Is it possible I damaged the hydraulic pump bearings to cause this problem by over-tightening belt, or is it it more likely to be old-age pump failure? (Have owned car for over 2 years, and suspect pump is on original).
No, there are no bearings in these pumps, it is run on a teflon coated bush inside the plate behind the pulley, if yiu had damaged it here, then it would also damage the seal and spring a leak.

3/ Is it usual for these pumps to fail gradually? Is it safe to drive the car a few hundred more miles before replacing the pump?
Yes they will usualy fail gradually, with the steering going first. It should be ok to drive as the suspension and braking is done from the same pump but a different part of the pump.

Regards
Slim.

Post by **Peter.N.** » 30 Apr 2007, 17:28

Make sure that the drive belt is not slipping before doing anything else.

citronut · Post by **citronut** » 30 Apr 2007, 19:25

you could also check the state of the citro blood,and tank filters
regards malcolm

AndersDK · Post by **AndersDK** » 30 Apr 2007, 23:37

Its not common that both circuits in the pump fails.
One part of the pump is completely separate from the other part.
A 2 piston part serves suspension & brakes, ie.e it feeds the accumulator and pressure regulator.
A 6 piston part directly feeds the power steering.

Usually the steering starts becoming 'notchy' and heavy if the pump fails.

As adviced check belt. Its GOT to be INCREDIBLE tight.
Also check fluid level, when suspension is set to highest.

You are absolutely sure its the correct green LHM fluid ?
Check the large dia feed hose to the pump has no surface cracks, especially over the studs. Also check the hose is secure and a leaktight fit both ends. The hose is under vacuum, will not leak fluid if not tight. But pump will take in air, whick exactly feels like a weak pump.

Mandrake · Post by **Mandrake** » 30 Apr 2007, 23:50

slim123 wrote: 2/ Is it possible I damaged the hydraulic pump bearings to cause this problem by over-tightening belt, or is it it more likely to be old-age pump failure? (Have owned car for over 2 years, and suspect pump is on original).
No, there are no bearings in these pumps, it is run on a teflon coated bush inside the plate behind the pulley, if yiu had damaged it here, then it would also damage the seal and spring a leak.

Hi Slim,

Are you sure about that ? When the shaft seal is on the suction side of the pump, and when the pump body is nearly level with the LHM tank ?

I've been having problems with the pump in my car - initially (a year ago) I suspected it of having a leak somewhere on the suction side as I was hunting down an air bubble issue. (Causing various issues including harsh ride - there is a long complicated tale behind this that I won't go into just here...)

A couple of months ago I put new seals in the pump (all apart from the shaft seal which can't be replaced) and it seemed to solve the problems temporarily (no air bubbles, much faster lifting, good ride etc) - but a couple of months on and the pump is now very noisy - the car is very slow to lift, the steering is a bit heavier, and the air bubbles and harsh ride are back.

As I've replaced all the other seals, I've come to the sad conclusion that the shaft bearing/bush is failing - and that because of that the shaft seal is no longer sealing 100% and is allowing air to be sucked in along the shaft as it rotates.

IMHO if the bushes are badly worn the shaft can't be held in central alignment against the side thrust from the aux belt and also the load of the pistons pressing on the eccentric cam - which would tend to cause the shaft to wobble as it rotated. Couple that with an old hardened seal and you potentially have a variable leak.

Plausable ?

3/ Is it usual for these pumps to fail gradually? Is it safe to drive the car a few hundred more miles before replacing the pump?
Yes they will usualy fail gradually, with the steering going first. It should be ok to drive as the suspension and braking is done from the same pump but a different part of the pump.

In your opinion, what goes wrong in a "gradually failing" pump ?

I've heard people say that the pumping capacity of the pumps starts falling off as they start to fail, but how is this so ? Has anyone stripped a pump with very poor pumping capacity to see whats wrong with it ?

Is it due to:

a) Wear in the pistons causing leakage around the piston in the pressure stroke ?

b) Leakage in the non-return valves associated with the pistons causing leakage back through the non-return valve on the intake stroke of a piston ?

c) A suction leak ?

Or many of the above ?

I mention C because it occurs to me that any air being sucked in by the pump will reduce the pumping capacity proportional to how much air is being sucked in.

Hypothetical example - a single piston pump with a 1cc per revolution capacity.

Sucking in only oil - 1cc of oil at atmospheric pressure, pumping it to the output - the pressure rises to 170bars, but its still 1cc of oil you're putting out for the stroke, minus a tiny amount of leakage past the piston, efficiency close to 100%

Sucking in 0.5cc of air and 0.5cc of oil at atmospheric pressure - as soon as the pump tries to output this under load the air will be compressed down to almost nothing (as the pressure is going from 1bar to 170bars, the air is compressed by 170 times) so you only output 0.5cc of oil from the full stroke, and a tiny amount of compressed air - the oil pumping capacity of the pump is effectively halved and efficiency is down to 50% even though the resulting oil/air mix, by volume, only has a tiny amount of air in it...

Can anybody see any holes in this idea ? I have definately seen a strong correlation on my pump between fast lifting and good ride and few bubbles, and slow lifting, harsh ride, and lots of bubbles...and you would think if the reason for failure of the pump was just piston wear that the loss in capacity would be permanent and not varying daily with temperature and other random factors ?

Regards,
Simon

xantiadave · Post by **xantiadave** » 01 May 2007, 09:56

Thanks all for the comments and advice.

Fluid and filers definitely OK - clean, and changed last July. Drive belt is very tight.

LHM reservoir outflow pipe tight, and no obvious cracks, but definitely deteriorating. There was a spare section left in the back of the car when I bought it (looks like the section for out of reservoir to connect somewhere immediately below). Perhaps it's time to fit that before investing in a new pump! Could be a lot cheaper

Anyone know how does this section of pipe connects / seals at the non-reservoir end? i.e. will I need to buy new seals before statring the job?

Cheers,

Dave.

deian · Post by **deian** » 01 May 2007, 10:03

One possible flaw that may or may not matter.... the effect of temperature on metals, on older unit, the metal may have been exposed to high/low temperatures over and over, and this could possible create metal fatigue, so once the car is warmed up the metalmay shrink and expose leakage anywhere inside the pump???

Mandrake · Post by **Mandrake** » 01 May 2007, 10:37

deian wrote:so once the car is warmed up the metalmay shrink and expose leakage anywhere inside the pump???

Doesn't metal usually expand with heat ?

Regards,
Simon

jeremy · Post by **jeremy** » 01 May 2007, 10:59

Its always worth checking that no air is getting into the pump. With a sound pump the only was is via the reservoir-pump hose - which may crack - or mare usually does not seal properly at one end. As you cleaned everything last year and probably disturbed this joint it may be worth having a good look at the tank-hose connection.

deian · Post by **deian** » 01 May 2007, 11:12

Ahhh, u got me there. I get confused on the 'little' things. I know left from right thankfully.

Ok then, maybe the metal is warped because of fatigue?

AndersDK · Post by **AndersDK** » 01 May 2007, 11:58

You are on the right track at least Deian 8)
The 6+2 hydpumps have a habit of snapping their housing bolts, even crack in the plastic part of the housing.
This situation is clearly followed by LHM leaks from the pump body.

deian · Post by **deian** » 01 May 2007, 12:08

Mandrake · Post by **Mandrake** » 01 May 2007, 12:09

AndersDK wrote:You are on the right track at least Deian 8)
The 6+2 hydpumps have a habit of snapping their housing bolts, even crack in the plastic part of the housing.
This situation is clearly followed by LHM leaks from the pump body.

Plastic part ?

My 6+2 pump has no plastic parts ? (And I've stripped it down before)

Are there later/earlier versions that are part plastic ?

Regards,
Simon

AndersDK · Post by **AndersDK** » 01 May 2007, 12:12

yes - the end piece is a solid plastic block on earlier production 6+2 pumps.