Random sinking of nose (xantia)

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
User avatar
Chris570
(Donor 2020)
Posts: 1461
Joined: 12 Dec 2009, 14:10
Location:
My Cars:
x 29

Random sinking of nose (xantia)

Post by Chris570 »

1999 HDi Exclusive

every now and then when the electrovalves open the front will sink about 2-3 inches and then pump back up. it doesnt matter if the engine is running or not as its done it coming out of a corner before and also when opening the door.

any ideas as with it doing it when driving i'd say its getting on the verge of dangerous.

Cheers guys
2006 C5 HDi 170
1998 Xantia Activa S1
1971 D Special
2006 C3 1.6 HDi SX,
CitroJim wrote: I'm a pink fairy
A 1/3 of Team WFA 'Clarkson'
User avatar
CitroJim
A very naughty boy
Posts: 49518
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6156
Contact:

Post by CitroJim »

Chris, there are two possibilities here...

Either, your front hydractive sphere my be ruptured. It's a three layer one usually and these are either perfect or flat/ruptured with no leeway; they can go suddenly.

Or, you have a pressure regulation fault/lazy pump which is causing your front anti-sink valve to close whilst on the move and the sink you are experiencing is the result of the pressure rising to cancel the mainline/corner sphere differential and reopening of the valve.

The first can be tested by doing teh classic bounce test. Start up, allow full pressure to be developed, switch off, shut all doors and then bounce the front. After 30s when the hydractive system switches to hard, you should feel the front go very hard. Open a door to initiate soft mode again and you should feel the front go soft if the hydractive sphere is good.

The second can be provoked by aggressively bouncing the front with the engine idling. If it starts off soft and then suddenly goes high and hard, signifying the anti-sink valve has closed then that's the problem; low mainline pressure has caused the anti-sink valve to close. In doing this test it may be useful to have an assistant pump the brakes to simulate more load on the hydraulics. If the valve is closing in this fashion, giving the bouncing a rest will allow the pressure to recover and reopen the valve causing the front to both go soft again and drop.

Compare and contrast with your V6 if necessary...
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
Post Reply