HP pump clatter

B-Hive · Post by **B-Hive** » Fri Jan 28, 2011 9:13 am

Hoping that the HP pump in the GT would be okay but way beyond that I think it may be on its way out.

The rattle when its kicks in is not great but acceptable (compared to the pump in the TRS)... BUT...There is a random clatter (almost rumbling grindy sound) from the pump when it is idle.. I know that a possible cause is air in the pump but ...a) how do I actually go about bleeding the pump and...b) I cannot understand how air can be trapped indefinately as most pump systems will purge themselves of air eventually if there are no air leaks on the input side. (which as far as I can see is the case) ..

So a recond pump maybe on the shopping list unless anyone can shed some light on this slightly dim situation.

Is it only the BX pumps that suffer from being noisy...I have never heard a noisy pump in a DS, CX or GS

Thanks

citsncycles · Post by **citsncycles** » Fri Jan 28, 2011 9:48 am

I cannot understand how air can be trapped indefinately as most pump systems will purge themselves of air eventually if there are no air leaks on the input side. (which as far as I can see is the case) ..

You may have answered your own question here. I'm not an expert on the BX system, but on general exprience I'd advise you check any joints on the input line to make sure they are tight, as well as the general condition of the pipework. A small enough hole may draw in air as the pump demands fluid, yet not leak as that part of the system is not pressurised.

Is it only the BX pumps that suffer from being noisy...I have never heard a noisy pump in a DS, CX or GS

I've been told that compared to the DS & CX, the BX pump is more built down to a price, although it was about the only thing that didn't give trouble on my last BX. The GS pump is a totally different animal, being a single cylinder linear pump, who's biggest failing is the rubber cover for the inlet.

Gibbo2286 · Post by **Gibbo2286** » Fri Jan 28, 2011 11:55 am

Before diving into the pump replacement, it might be a good idea to check the condition of the belt, flat spots on the belt or the belt riding too deep in the pulley can cause clattering noises. Gibbo.

B-Hive · Post by **B-Hive** » Sat Jan 29, 2011 6:19 am

Just rechecked all the hoses and they're all tight and in good condition. Belt looks newish and no irregularities there.

Noise is definately coming from within the pump itself.

Like i say, on load there is a little acceptable rattle but off load it sounds as though the random clatter is associated with the pump's cut in/out valve if there is indeed something like that inside the pump.

My limited understanding of the pump is that when the pressure regulator (external) says "thats enough" it then blocks the flow of pressure from the pump, and this in turn indicates to the pump to cut out.. Much like the cut out on a petrol bowser. It sounds like the pump's internal mechanism for checking the what the regulator is doing has gone berserk. Almost like that pump "cut in sound" wildly and randomly trying to decide what to do.

OR....This may point to the regulator that is sending the pump mixed signals..

How does that sound to you learned folk, and do you think it is a fault within the pump or maybe as suggested in the regulator, in which case is there a quick fix.. Would that reseting of the regulator ball bearing method do the trick??

cars stays up well after shut off and all other spheres appear quite new so dont think its the accumulator sphere.. again, please correct me if you think I'm misguided on that one..

Gibbo2286 · Post by **Gibbo2286** » Sat Jan 29, 2011 10:02 am

The pump doesn't have any internal on/off system it's just a high pressure pump pumping continuously, the regulator simply diverts the excess pressure back to the reservoir.

Here'a an interesting link you might like to look at. Gibbo,

http://www.citroenet.org.uk/miscellaneo ... cs-16.html

Linegeist · Post by **Linegeist** » Sat Jan 29, 2011 11:10 am

Just seen this - and it's something I had a run-in with early last year when I replaced the slightly noisy HP pump on my Athena with a 'reconditioned' one from a well-known supplier of hydropneumatic parts...... Basically, the series of replacements I got were worse than the existing pump.

After fitting a succession of these noisy/non-working/jerky pumps from the supplier, I tore the noisiest one apart in the workshop - not with any intention of fixing the damned thing, but to find out what the hell was going on inside that freshly green-painted shell.

The conclusion that I eventually reached was simply "wear".

The reconditioned pump I took apart was reconditioned inasmuch as it had been cleaned, checked over and repainted but, as parts for these pumps are now about as readily available as virgins in Manchester, any parts that are reusable appear to be pressed back into service with new additions being kept to a minimum.

One of the most common fixes, apparently, is to flip over the small one-way poppet valve discs in the pump elements so that the unworn side is presented to the valve seat face, theoretically solving any leakback or poor seating problems from the appreciable groove that can wear into the faces. The only drawback with this approach is that no allowance is made for wear on the periphery of the steel discs or the face of the valve seat itself. Thus, in service, the disc can 'chatter' radially under zero load conditions, when there is no cushioning effect from pressurised LHM to hold it in place. I suspect this is what we hear from a worn pump, amplified by the pump body and its bracketry.

Good engineering practice would dictate that these worn discs are replaced after the extended mileages they usually deliver, along with their springs. Unfortunately, as they aren't available (as far as I know), and the only other option would be to have a batch made at considerable expense (making the refurb process less cost effective) we have the situation where our HP pump refurb system is, from my own experience at least, hit and miss.

I found no way round this problem, except to keep insisting on replacement pumps from the reconditioner, until I finally got one that was quiet AND that worked. The main lesson I learned is that noise is not an indicator of how effective a pump is - it's the pressure it generates (and maintains) that is the main yardstick. If you can live with the noise, and the pump's reliably delivering the goods, then you're onto a winner.

In my case, one of the quieter pumps I received as a replacement had a nasty habit, out of the box, of randomly failing to deliver enough supply to operate the steering smoothly. I nicknamed these events "All Bran Moments" in honour of the rapid sphincter-tightening effect it could have when it occurred while navigating roundabouts. If your pump doesn't do any of this naughty stuff, buy it a bottle of fresh LHM and have a party!

Gibbo2286 · Post by **Gibbo2286** » Sat Jan 29, 2011 2:53 pm

Have you ever tried to get those valve discs made Linegeist? There's lot of small engineering workshops who will do small jobs like that for not much dosh.

As an example last year my Karcher workshop pressure washer packed up and instead of pumping the water out just let it dribble out of the bottom.

I stripped it down and found that the plating had flaked off the pistons and destroyed the seals.

New pistons were only available from Germany at over £50 each and I needed three so that wasn't going to happen,

I bought a suitable length of stainless steel rod from Metals 4U, called in at the local engineering works with an old one for a pattern and they machined them up in just a couple of days, "How much do I owe you? I said, "Give us a fiver." was the reply. Gibbo.

B-Hive · Post by **B-Hive** » Sat Jan 29, 2011 3:11 pm

yes... well aside from the non load-din the pump operates perfectly, but the racket sounds at best "raw" and terminal..I'm not a purist but I dont think I'd be content to live with the slight doubt that the pump could implode and disintegrate...prefer to spend the dosh and at least have the newby pump sitting in the boot...ahh now there's my solution...just have to find someone who will supply one!! not sure if pleides are still operational anywhere else let alone here in Oz..