LHM change- what a difference

_kid_ · Post by **_kid_** » 06 May 2006, 20:39

Ive just changed the LHM in the xantia.

Prior to the change when starting from cold (e.g. overnight) the stop light took 8 secs to go out, the suspension took another 35 secs before fully up.

Post the change, stop light still the same, but the suspension is now fully raised in a further 17secs, why such a difference, i.e. half the time

Also the front used to rise in steps, now it rises in one swoop. Again why

No other work has been done and the LHM was not too bad, it was yellow, rather than the neon green it now is

Post by **Peter.N.** » 06 May 2006, 20:44

Did you clean the filters? if not, changing the fluid has probably washed them out a bit.

_kid_ · Post by **_kid_** » 06 May 2006, 20:55

Peter.N. wrote:Did you clean the filters? if not, changing the fluid has probably washed them out a bit.

yes they were cleaned,they did not look too dirty

deian · Post by **deian** » 06 May 2006, 21:18

Awwwww stop it _kid_ you're making me jealous here, I wanna do mine too. Is the ride better? If so, what way?

Thanks

_kid_ · Post by **_kid_** » 06 May 2006, 21:23

deian wrote:Awwwww stop it _kid_ you're making me jealous here, I wanna do mine too. Is the ride better? If so, what way?

Thanks

go for it! if i can change it so can anyone

re. the ride i can't feel any noticable difference, but if the lhm was very dirty i guess it would be noticable.

LeeDJC · Post by **LeeDJC** » 06 May 2006, 22:48

Did you hydraflush it as well?

_kid_ · Post by **_kid_** » 06 May 2006, 23:52

LeeDJC wrote:Did you hydraflush it as well?

No, just used the 'genuine' total LHM from gsf @ £4/litre + vat. Which should translate as your paying for the chevrons on the bottle!

deian · Post by **deian** » 06 May 2006, 23:54

i remember two weeks ago going to my citroen dealer who quoted me £47.50 for 5 litres of Hydraflush! I would knock a tenner off for the LHM from dealers. I'm glad you had the sense to go to GSF.

_kid_ · Post by **_kid_** » 07 May 2006, 00:01

deian wrote:i remember two weeks ago going to my citroen dealer who quoted me £47.50 for 5 litres of Hydraflush! I would knock a tenner off for the LHM from dealers. I'm glad you had the sense to go to GSF.

gsf hydraflush is around £15+vat

The LHM from the dealer was (surprisingly) only £4.40 +vat. It was a no brainer for me, gsf Leicester is only 1/4 mile from me!

LeeDJC · Post by **LeeDJC** » 07 May 2006, 08:24

So hydraflush is pretty cheap then? Cool - I think thats the next job for me. The LHM is pretty mucky - although when I changed the spheres the other week, the LHM that came out of one of them was reasonably clean.

Post by **smashymike** » 07 May 2006, 13:46

I'm gonna do mine soon so what was the exact procedure i need to follow? Is changing the LHM the same as bleeding the brakes or am i way off beam? MY Xant has 'intermittent' braking shall we say, as though the abs is doing too much of thework. It does stop but i'm sure that there's air in the circuit somewhere, most likely the rear (are there two separate braking circuits?) so i've penned in a sphere change for the rear soon. But i've always thought the LHM business would improve things. Sounds like it could be a good move. As far as i'm aware this has neever been changed. Cars a 95(N) TD SX .... so what do i do and don't do? Ta.

rossnunn · Post by **rossnunn** » 07 May 2006, 16:30

most modern braking systems use a cross circuit system, so the NSF is on the same as the OSR, so that in the event of a circuit failing the driver can still kepp the car in a straight line. I suspect the Xant is done the same

Kowalski · Post by **Kowalski** » 07 May 2006, 16:52

rossnunn wrote:most modern braking systems use a cross circuit system, so the NSF is on the same as the OSR, so that in the event of a circuit failing the driver can still kepp the car in a straight line. I suspect the Xant is done the same

The Xantia is split two ways, front to rear, that is fairly normal for a hydraulic suspened Citroen. I think the ones with ABS are 3 channel ABS, two front channels and one rear, so they may have some additional isolation at the front but I'm not entirely sure about that one.

_kid_ · Post by **_kid_** » 07 May 2006, 18:12

smashymike wrote:I'm gonna do mine soon so what was the exact procedure i need to follow? Is changing the LHM the same as bleeding the brakes or am i way off beam? MY Xant has 'intermittent' braking shall we say, as though the abs is doing too much of thework. It does stop but i'm sure that there's air in the circuit somewhere, most likely the rear (are there two separate braking circuits?) so i've penned in a sphere change for the rear soon. But i've always thought the LHM business would improve things. Sounds like it could be a good move. As far as i'm aware this has neever been changed. Cars a 95(N) TD SX .... so what do i do and don't do? Ta.

For the low cost of the change id change it, i would guesstimate mine had not been changed for 3+ years, i think two years changes is more suitable than three year changes.

To change the LHM, Haynes has the correct info but i believe it’s in the wrong order. I would do it something like this:

1) Start engine, put suspension to lowest, open 12mm pressure screw about 1/2 a turn (you’ll hear a 'whoosh' noise), wait one minute, then stop engine

2) Remove fluid hoses from the plastic support holder on the lhs of the reservoir.

3) Disconnect the green/brown-wiring plug

4) Undo the two retaining bolts on the back

5) Remove the plastic support pipe holder off the reservoir completely

6) Remove the centre section black clip

7) Pull the front of the LHM reservoir out of its retaining hole, you may need a screwdriver to gently lever the reservoir out.

8 ) There should now be some flexibility in the centre section and the reservoir, to move the centre section out without removing the pipes, you’ll will need to turn the reservoir towards the hoses and slowly pull the centre section out. The moon shaped filter may come loose, but you can take it out of the reservoir later

9) Drain old LHM, remove and clean filters in petrol and dry, clean the LHM reservoir

10) Re-fit filters; ensure the clip at the bottom of the filters is securely holding both filters.

11) Put the centre section back into the reservoir (this is easy as the reservoir is empty), refit the reservoir, re-fit the plastic support hose holder, refit centre section clip, refit hoses back in holder, refit the green/brown wiring plug

12) Refill reservoir with initially around 3litres of LHM, start car, put in high, wait a couple of mins, then close the 12mm bleed screw.

13) As the suspension is in high check the LHM level refill until the correct level, do citrobics a few times, recheck level

I found 4litrs of LHM is enough.

Mandrake · Post by **Mandrake** » 07 May 2006, 20:52

_kid_ wrote:1) Start engine, put suspension to lowest, open 12mm pressure screw about 1/2 a turn (you’ll hear a 'whoosh' noise), wait one minute, then stop engine

Unfortunately this will not work for any anti-sink model - as soon as you open the pressure release screw the anti-sink valves both close and the suspension won't go down any further.

Might I suggest:

1) Start the engine, pressure release screw closed, put the suspension on low, wait 2-3 minutes, stop the engine, open the pressure release screw.

Thats the recommended way to depressurize an anti-sink model. The 2-3 minutes is because even though the suspension stops visibly falling after about 30 seconds, oil continues to flow back to the tank for at least 2 minutes, and you don't want some flowing back AFTER you've disconnected the tank

Regards,
Simon