anti-sink sinking?

deian · Post by **deian** » 08 Aug 2006, 22:17

Hi peeps!

I'm sure my car sinks overnight you know, can my anti-sink car sink for some reason? if so why?

Thanks

AndersDK · Post by **AndersDK** » 08 Aug 2006, 23:21

Yes - if the antisink valve leaks

- but more likely : if one of the rear cylinders leaks. Its easy to test : the rearmost plastic pipe from the rear cylinder bellow is the leak-off pipe to the reservoir.
One of the pipes (cylinders that is) must have some frequent dripping if the car sinks.

Mandrake · Post by **Mandrake** » 09 Aug 2006, 01:25

Does it sink at both ends ? Right to the bump stops ?

Mine seems to stay at exactly the same height at work over 8 hours, but after 14 hours overnight it goes down about an inch at each end..

It looks like the anti-sink sphere can infact also affect the sinking rate as the anti-sink sphere on my Dad's car has recently punctured, (complete with nitrogen bubbling into the rear brakes) and it now goes down over night and takes a lot longer to lift...

Regards,
Simon

deian · Post by **deian** » 09 Aug 2006, 10:25

it can drop noticeable after 6 hours, and it will drop about the same amount overnight too, it doesn't drop to the stops, just a couple of inches on both sides, haven't seen any puddles of LHM anywhere, I will check along the pipes this weekend, when i start her up the stop light stays on for about 5 seconds, I guess this is due to my slack belt at the moment,

thanks

Mandrake · Post by **Mandrake** » 09 Aug 2006, 10:44

You wont see any external leakage that would cause the car to go down without going through your entire tank of LHM in no time flat

Theres nothing wrong with the stop light going out after 5 seconds if it's been left overnight... mine takes about 8-10 seconds.

Regards,
Simon

davetd · Post by **davetd** » 09 Aug 2006, 21:06

Have you tried citerobics ?

davetd

deian · Post by **deian** » 09 Aug 2006, 22:15

i do citrobeotics all the time, last time i did it was on sunday.

davetd · Post by **davetd** » 10 Aug 2006, 20:34

maybe you've over done it

deian · Post by **deian** » 10 Aug 2006, 22:22

maybe i have, i do it at least once a week

AndersDK · Post by **AndersDK** » 10 Aug 2006, 23:52

davetd wrote:maybe you've over done it

Can not be overdone.

AndersDK · Post by **AndersDK** » 10 Aug 2006, 23:54

deian wrote:maybe i have, i do it at least once a week

No -
If there is any weakness in the suspension - a Citaerobics sequence is a fast test.

AndersDK · Post by **AndersDK** » 11 Aug 2006, 00:12

Please note :
When we LHM heads mention leak-back or leak-off - we are referring to internal leaks. Nothing that creates green puddles under the car.

To recap on leak-off & return pipes :

1) all cylinders and slide valves have a certain amount of leak - by design - to keep the mating surfaces wet with LHM for lubrication.
This leak must be lead away not to build up the system pressure from the component. Therefore the leak is allowed to collect in build-in cavities - which then in turn have a leak-off (or leak-back) hose connected to the reservoir.
The nature of this lubricating leak makes it a VERY low pressure. It is in fact rather a seepage and is seen as very slow dripping - one drop pr minute up to one drop pr several minutes.
Some components - like the suspension cylinders - have O-rings thát wears out over time and then the leak-off increases. At times up to the point where the leak-off hose may become pressurised. This is a common problem on BX front cylinders.
But the rear cylinders on all models are prone to slowly increase the leak-off as well.
The leak-off pipes are always small diameter plastic and/or rubber.

2) Return flow from components only happens when a pressure must be released and therefore a certain amount of LHM fluid must be returned to the reservoir.
F.i. if the suspension needs to decrease the pressure in the case a passenger leaves the car.
Or when you release the brake pedal.
These return pipes are semi-pressurised - as the fluid led into the return pipes is coming from a high pressure source. As the fluid only meets the resistance of the limited pipe diameter - the pressure is not really a pressure but rather a high speed flow towards the reservoir.
Return pipes are the larger diameter plastic and rubber hoses. In a few cases it will be rigid steel pipes aswell.

deian · Post by **deian** » 12 Aug 2006, 19:01

thanks for clairification anders. i will do citrobeotics now to see what happens, funny thing is now ok, is the car rides a LOT better and smoother, u know that harsh ride i was gettting, it's like 60% better, is this sinking making the car ride better maybe?

it actually feels so so floaty now, and it's an absolute joy to drive, i went for a nice drive last night on some good roads, did about an hour and half each way, and with the lovely suspension and 2.1td engine i was making amazing progress... only for £5 topup on diesel!!

deian · Post by **deian** » 12 Aug 2006, 20:02

citrobeotics went well, will report back in the morning as to sinking overnight.

davetd · Post by **davetd** » 14 Aug 2006, 21:42

AndersDK wrote:
davetd wrote:maybe you've over done it
Can not be overdone.

I was only joking

By the way my '93 non anti sink model that sunk within an hour, that I had twice (unsuccessfully tried to get advice on from the forum because people kept changing the subject on the thread

) now stays up all night since I removed the LHM resevoir to change the gearbox mount and noticed a tiny pipe (the size of a WD40 straw) disconnected from it.

davetd