Changing Lhm, Instructions

About a year ago some kind person on this forum posted full (simple) instructions on how to change the LHM fluid on an XM, unfortunately I can't find it and wondered if anyone could help.

The car is a 1996 2.5td and I wondered if someone could also tell me where it is that I depressurise the system from and its location. Once I change the LHM and put the Hydraflush in do I need to bleed the system then?

Thanks again everyone

This post has been edited by jackyboy on October 30, 2007 05:33 pm

to depressurise you must put car in lowest suspension setting and open (crack open only) the screw on the accumulator block. on the 2.5 its just to the right of the engine block at the front (leaning into the engine bay) underneath the accumulator sphere buried half way down. not much, if any, access from the top!!

it is easily reached from underneath once you know where to look but do NOT do this without supporting the vehicle to prevent it lowering on to you. once lowered there is no room to get your arm underneath.

you will hear it hiss as the pressure escapes.

a very thorough purge of lhm with hydraflush would require bleeding at all brakes but the consensus seems to be just run it for 1000 or so miles. the haynes manual describes what to do to prime the system (if needed in the event)

the lhm tank and its filters must be removed and cleaned thorough to make the exercise worth it. Also if you are keen it seems you need to strip down some of the components (rear hydractive valve i think?) as the hydraflush does not clean this bit.

Hi Gav

Total says flush up to 5,000kms, that's about 3,000mls. I've seen it on bottles.

My experience is you won't get anything with 1,000mls. My car started being soft (speaking of suspension) at about 2,000mls. It gets better each week as I reach 4,500mls now. My regulator cycling time has gone up from about 13secs to 17secs now, which is a 30% improvement I cannot explain but, if not anything else, shows that the 4,500mls did not do any wear to the system (seals), the opposite.

Also, I read recently in a French CX forum that in france both dealers and indys advise "leave it in way over the specified", and reports of people having left it in for things like 10,000mls-15,000 or 1-2 years without problems. Also people using hydraflush as standard in very cold climates. Of course all that is just things I read, I can only ascribe to my personal experience described above.

Jackyboy,

a little tip: when u r ready, before u start engine again, have the depressurisation bolt in the open position an run the car as such for a few mins. This way u'll avoid sending and spreading any air sucked by pump, all over the system. Any air existing will be bled through the LHM tank -that's where the LHM returns when the said bolt is open-. Then, close bolt and hopefully car will raise.

regards
George

Brakes is the only place in the circuit air cannot move further. I'd say bleed ur brakes definitely, at least when u put LHM back if not on the flushing ocasion -I'm not aware of any difference bleed will do as far as "cleaning" goes-. If there's alot of air in them, you'll notice the car's tail rising when applying brakes while cruising -as if you had a car with an extremely soft suspension-. That's not normal XM behavior -it brakes almost flat if the rear brakes are clear of air-.

regards
George

Thank you for all that info. But..... I have found the place to de-pressurise from underneath but can I access it from above? Would it be ok to put the front of the car up on ramps and do the LHM change like that or does the car need to be level.

Sorry if I sound a bit tick but I am only a trainee mechanic (63 year old) Having said that I have changed discs, pads, Track rod ends, glow plugs, starter motor and stabiliser link bars so I am learning. Where I'd be without this site I don't know.

Incidentally, the only reason I changed some of the afore mentioned items was because I had them, bought in various auctiions etc. The car has still only done 68k and maybe it is time to sell?????????

It doesn't really matter if car is level, but the suspension has to be fully compressed so that you have sent most old LHM back to the tank.

Hmm, don't know if the 13mm bolt is accessible from above on a 2.5. You can get at it on my V6 if u spend some time to work out its position -my indy does it without even looking, I need to study the place for a while to locate it...

cheers
George

on the 2.5 it is just possible to get to the screw from above. BUT you have to know where it is before you start by looking from underneath because there is not enough clear space for an arm and an eye!

I put the spanner in place from underneath then move it from above and leave it in situ until i've finished