Basically, my Xantia sinks at the front when left for more than a couple of hours. This happens on normal and high (but not low which I find very interesting).
After a quick chat it transpires that this could be the anti sink valve failing rather than the front struts wearing. If it was the latter, it would only sink on normal height. The only reason I can think of is due to the wear of the struts being in the middle part rather than at the two extremes. Am I on the right tracks?
If I'm honest, its not a job that I'm worried about fixing as I think its kinda cool, more for the knowledge if I change my mind
Front sinking on the Xantia
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Front sinking on the Xantia
Kev
'19 C4 Cactus 130 Flair
'19 C4 Cactus 130 Flair
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Kev, the anti sink valve is normally very reliable and trouble free but the front ones do leak from time to time.
The antisink valve is between the strut feeds and the height corrector and isolates the struts completely when it operates.
It operates when the main system pressure falls below that in the front corner spheres and one cause of sinking can be flat front spheres.
Also, a leak on the pipework between the strut tops and the antisink valve can cause it too, sometimes it takes only a very small leak.
The antisink valve is located under the LHM reservoir and can leak unnoticed due to its hidden locatoon and it being generally oily under there. It's a tubular thing with with black circular end caps and it's these caps that can leak.
Don't confuse the antisink valve with the security valve. The latter has an electrical switch on top of it. It's this switch that operates the STOP light.
A way to test the strut health is to disconnect their leakage returns and see if any great quantity of LHM flows from them. When the suspension is not moving, there should be very little leakage. If LHM really gushes then the strut is worn. I doubt it is this though as you're corect that on extreme high the piston is on an unworn section. On worn struts I've seen, a visibly worn section can be seen on the piston, almost as it an area of plating has flaked off revealing a slightly different colour underneath. This wear happens on the thrust side of the strut piston - toward the front.
The antisink valve is between the strut feeds and the height corrector and isolates the struts completely when it operates.
It operates when the main system pressure falls below that in the front corner spheres and one cause of sinking can be flat front spheres.
Also, a leak on the pipework between the strut tops and the antisink valve can cause it too, sometimes it takes only a very small leak.
The antisink valve is located under the LHM reservoir and can leak unnoticed due to its hidden locatoon and it being generally oily under there. It's a tubular thing with with black circular end caps and it's these caps that can leak.
Don't confuse the antisink valve with the security valve. The latter has an electrical switch on top of it. It's this switch that operates the STOP light.
A way to test the strut health is to disconnect their leakage returns and see if any great quantity of LHM flows from them. When the suspension is not moving, there should be very little leakage. If LHM really gushes then the strut is worn. I doubt it is this though as you're corect that on extreme high the piston is on an unworn section. On worn struts I've seen, a visibly worn section can be seen on the piston, almost as it an area of plating has flaked off revealing a slightly different colour underneath. This wear happens on the thrust side of the strut piston - toward the front.
Jim
Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...