Frequency of hydraulic pump 'clicks'

Our most popular forum is for Citroën problems, discussions and chat.
Specialising in AX, BX, ZX, Xantia,C5, Xsara, Saxo and XM. CX, 2cv & Berlingo, all are welcome.NOT for selling cars/parts!

Moderator: RichardW

alf
Posts: 21
Joined: Mon Aug 13, 2001 2:46 am
Location: United Kingdom
My Cars:

Frequency of hydraulic pump 'clicks'

Postby alf » Wed Jan 23, 2002 10:19 am

When buying second hand Xantia TD, whats the click frequency (technical term) one be looking for and what rate should sound warning bells?
0 x

JohnD
Donor 2016
Posts: 2446
Joined: Thu Mar 15, 2001 12:41 am
Location: Epsom, Surrey
My Cars:
x 2

Postby JohnD » Thu Jan 24, 2002 12:45 am

Hi Alf - If it clicks once every half to one minute, you can take it that the accumulator is OK. As it gets near to once every few seconds, be ready to replace it.
0 x

alf
Posts: 21
Joined: Mon Aug 13, 2001 2:46 am
Location: United Kingdom
My Cars:

Postby alf » Thu Jan 24, 2002 5:22 am

Thanks John D, Could you clarify a point for me? Is it the pump that clicks or the accumulator sphere. Pump = loadsamoney, Accumulator sphere = not too bad.
TVM
0 x

henrysheil
Posts: 6
Joined: Mon May 14, 2001 3:42 pm
Location: Australia
My Cars:

Postby henrysheil » Thu Jan 24, 2002 12:10 pm

Hi Alf,
The sphere is a pressure vessel with a bladder inside, the bladder (like a balloon)being pressurised with Nitrogen gas. The LHM goes in the end and "squeezes" the bladder from the outside. It can't make any clicking noises.
The pump does the clicking, but it is turned on and off by the regulator which is where the sphere screws into. The regulator's commands to the pump to switch on or off are determined by the pressure in the system, and the rate of pressure loss/drop inside the system is governed by the precharge in the accumulator. When its precharge is low its ability to help top up hydraulic pressure in the system is reduced, so the pressure drops faster, so the pump has to cycle on and off more often.
Geddit? It's all very logical.
Henry
<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
Thanks John D, Could you clarify a point for me? Is it the pump that clicks or the accumulator sphere. Pump = loadsamoney, Accumulator sphere = not too bad.
TVM

<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
0 x

alf
Posts: 21
Joined: Mon Aug 13, 2001 2:46 am
Location: United Kingdom
My Cars:

Postby alf » Thu Jan 24, 2002 11:47 pm

Thanks Henry for an understandable explanation without the technobabble. As I understand it if its clicking frequently try changing the sphere before you start spending any serious money.
0 x

JohnD
Donor 2016
Posts: 2446
Joined: Thu Mar 15, 2001 12:41 am
Location: Epsom, Surrey
My Cars:
x 2

Postby JohnD » Fri Jan 25, 2002 12:53 am

Hi Alf - 99 times out of 100 the reason for the frequent clicking is the flatness of the accumulator sphere. Normally the pump is a long lasting item (providing LHM has been changed at recommended intervals), whereas the spheres last around three to four years.
0 x


Return to “Citroën”

Who is online

Users browsing this forum: No registered users and 1 guest