Sinking quickly

Kitch · Post by **Kitch** » Tue Sep 13, 2005 11:12 pm

What causes a BX to sink quickly once its been switched off? AFAIK most BX's I've owned or encountered usually do the same routine; back sinks within the hour, front overnight.

Well just before I started ripping the 16v apart, I noticed the rear was sinking down to the bottom shortly after being switched off and the front took an hour or so.

I can't find any leaks anywhere! Stumped really, are there any valves etc in the system designed to keep it up, or is that only XM's/Xantias etc?

OwenS · Post by **OwenS** » Tue Sep 13, 2005 11:30 pm

Pretty sure 'anti sink' is only a Xm/Xantia feature. Mine is sinking alot faster nowadays, when I first got it by morning it would have butt down, nose up posture...now it has nearly, if not completly, sunken to it haunches overnight....but what the hell the levitation is fun and makes people stare!! lol. Only downside is if you needed to make a fast getaway, eg robbed a bank!

As far as mine goes I think the numerous speed humps locally have dramatically loosened my once stiff struts so now the car sinks faster...and rides even better

sleepy0905 · Post by **sleepy0905** » Wed Sep 14, 2005 8:25 am

try putting some HYDRAURINCAGE in as you may have muck collectedin your BRAKE DOSEUR VALVE, if this doesnt work then you may have to replace the valve like i did as the seals get worn but they dont wear out mechanically,

tom · Post by **tom** » Wed Sep 14, 2005 8:47 am

Common wisdom is that the doseur leaks back, which it does. There may also be a leak back from the rear height corrector. The vast majority of BXs sink overnight and it is harmless if unsightly. The Xantia has anti sink to sort out this entirely cosmetic issue. One of the reasons why it is heavier than a BX!

Vanny · Post by **Vanny** » Thu Sep 15, 2005 5:46 pm

But if your keen then you can stick anti sink on a BX without too much hassle or even cost! Only real problem is the £100's of pounds it will cost to purchase pipe flaring tools from Pleides!

tom · Post by **tom** » Thu Sep 15, 2005 6:05 pm

You certainly can and I have considered it but, as you say the tools are rather dear so I've decided that I'll live with it!

jeremy · Post by **jeremy** » Fri Sep 16, 2005 11:23 am

many people have replaced doseurs and found they make no difference (myself included). I thought it was now reconed that the height control valve wore slightly and was responsible for rapid sinking.

I must say from obversations that all seem to sink right down in an hour or so.

Jeremy

DLM · Post by **DLM** » Fri Sep 16, 2005 2:42 pm

I think a lot of parts suppliers must have made money from "doseur paranoia" - the only time I've been seriously worried about a doseur performing its primary task was when I bought a 1993 TXD which sank rapidly at the rear but also hissed and ticked on a permament basis.

On reseating the ball-bearing in the PR, the ceaseless hydraulic shirring totally disappeared, until I put my foot on the brake pedal: back to square one. I did wonder whether someone had swapped in an old-pattern (pre-1998) doseur on this one and neglected to connect it correctly, but I never got as far as swapping the valve out, as the car fulfilled its use as a temporary stepping-stone BX and then was sold for a staggering £100 (staggering considering it was out of tax and MOT) to someone who needed a red wing and bumper.

sleepy0905 · Post by **sleepy0905** » Mon Sep 19, 2005 6:44 pm

I rebuilt my doseur valve with all new seals only cost about a fiver for the seals and that cured my problem

roscoe · Post by **roscoe** » Tue Sep 20, 2005 11:01 am

My 16V sinks at the rear in about 10-15 minutes but the front stays up for hours - and the pump kicks in about every 60 seconds or so. My TZD takes about 3 hours to sink at the rear, longer at the front and the pump kicks in every 15 seconds or so...and has done since I got the car back in '94. I've had new accumulator spheres on it, regassed ones and a new doseur valve with no difference to the cut in times...so figure I need to reseat the infamous ball bearing. All I need to know is which one it is..I understand there are two in the PR, one under the sphere and another one in one of the pressure lines. Which one of these is the one to reseat and other than it flying out and getting lost...any tricks to it...other than the neat one of trying to find a brass drift to do it with (sort of like rocking horse poo to find where I live in Oz!).

sleepy0905 · Post by **sleepy0905** » Tue Sep 20, 2005 11:55 am

I beleive the one to reseat is the one under the sphere but be carefull no to mishape the ball.

jeremy · Post by **jeremy** » Tue Sep 20, 2005 7:28 pm

The valve to re-seat is under the sphere. The only other one in the regulator is under the pressure relief screw and usually only gets discussed if there is a suspicion that someone has removed the screw and lost the ball.

To re-seat remove the sphere and then undo the 10mm? both holding the strange shaped metal plate in position. When you remove the plate he ball will probably fall out so place a tray underneath. Stick the ball back in the hole with a dab of grease and strike it once smartly with a soft faced punch. Make sure the ball doesn't come out, refit plate and sphere.

The first time I did it I hadn't got a suitable punch and used an old copper mig nozzle held onto a steel punch with an old hydraulic seal (ie rubber tube!) The reason for not using steel is that it may put a flat on the ball which will not seal then.

I can do the job on my BX TD from underneath with the car on ramps and I'd have thought your 16 valve was much the same in that area. Getting the regulator out isn't much fun even with a 3ft extension bar and so I'd do it on the car if possible.

To prevent syphoning I clamp the hose from the reservoir to the pump.

Let us know how you get on.

Jeremy

bernie · Post by **bernie** » Tue Sep 20, 2005 8:57 pm

Mine stays up for ages

M · Post by M » Tue Sep 20, 2005 10:08 pm

bernie wrote:Mine stays up for ages

Stop bragging - maybe these will help....

cavmad · Post by **cavmad** » Wed Sep 21, 2005 8:08 am

Marty wrote:
bernie wrote:Mine stays up for ages
Stop bragging - maybe these will help....

I followed your advice (above) and now my LHM reservoir is jammed solid with blue pills and the car won`t go or down. Should I have put them somewhere else?

My car sinks within minutes at the rear but if it won`t do any damage I can live with it. Oddly enough my 1.7 used to sink REALLY quickly all the way round then one day it stopped and took ages to go down (arf arf) after that and was never any trouble again. Maybe the what-do-ya-call-it had re-seated itself?