LHM drain or flush?

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Philip Chidlow
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LHM drain or flush?

Post by Philip Chidlow » Mon Apr 03, 2006 8:19 pm

My BXs LHM fluid seems a tad 'dirty' and I wondered if it really is necessary to drain the system and flush with Hydraurinçage (is that right?) etc. etc. as I've heard some folks do... Can I just drain the LHM - using a pump set up that I can borrow from my Citroen enthusiast neighbour - from the reservoir, then refill with new, clean LHM... Will I notice a difference?

Any advice welcome!
• 1992 Citroen BX TZD Turbo saloon, White, 94k miles
• 2003 Rover 75 CDTi Connoisseur Tourer, BRG, 145k miles.

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Post by Mr B » Mon Apr 03, 2006 9:57 pm

You need to remove the tank to drain the mucky LHM and clean the filters. Turn the steering full left hand lock, drop the suspension to low and release the pressure on the regulator. This will release as much LHM back to the tank as possible. Once all the cleaning has been done and you have pressure back in the system, bleed the brakes, as this will push clean LHM through.
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Post by adamskibx » Tue Apr 04, 2006 12:26 am

It seems like Mr B has given good advice. Regarding Hydraflush, ive no idea. My local Citroen specialist hates the stuff and says he would never dream of putting it in his BX, but the last BX I bought had hydraflush in it when I bought it and when I changed it back to LHM there were no problems. In fact i never had any problems full stop; But, if the height correctors are working as they should and your happy with the way the system is working at the moment, then a change to clean LHM and a filter clean, is probably the best option as it cant exactly do any harm, and is certainly better than noticably dirty LHM fluid.

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Post by Philip Chidlow » Tue Apr 04, 2006 8:39 am

Thanks for the advice, chaps. I will get my hands dirty soon...
• 1992 Citroen BX TZD Turbo saloon, White, 94k miles
• 2003 Rover 75 CDTi Connoisseur Tourer, BRG, 145k miles.

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Post by AlanS » Tue Apr 04, 2006 10:10 am

2 little bits of advice; if you've never had your hand inside an LHM tank before, be extremely careful of the inside edge of the tank; razor blades come to mind. Real easy to cut yourself on it. Image

Secondly, do a brake bleed on all 4 wheels. Brakes are dead ends and the last car I did was my Xantia which up to that point hadn't been all that flash in the way it rode. When I bled the rear brakes, I managed to drain about 250mls of very frothy liquid out which started out gold colour and ended up the right shade of green and we've all lived happily ever after. :lol: :wink:


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Post by Philip Chidlow » Tue Apr 04, 2006 10:17 am

Thanks for the tip, Alan.
• 1992 Citroen BX TZD Turbo saloon, White, 94k miles
• 2003 Rover 75 CDTi Connoisseur Tourer, BRG, 145k miles.

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Post by Oscar » Tue Apr 04, 2006 10:51 am

Hydraflush is worth doing - it cleans all the crud and dirt out of your system. There is an opinion that it stirs up dirt and can lead to blockages, but I don't agree.

I did it with my BX and I was surprised at how dirty the H'flush was when it came out after 2000 miles.

O
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Post by mnde » Wed Apr 05, 2006 12:22 pm

Like Mr B and Alan have said, it's a good idea to be thorough when you do this.

Definitely take the tank out. On the GSA I gave mine a good wash out with white spirit. Take the opportunity to clean off all the crud on the "lid" around the pipe connections and the level indicator. Wash the filters in white spirit then blow dry with an airline (or I've used a li-low footpump to good effect) and dry the inside of the tank using kitchen paper. The difficult thing is getting the lid back on without the large filter becoming unhooked and falling off inside. It's quite a tight fit. I've made the mistake of putting the tank back in the car before doing this.... and then repeatedly having to dip my hand into the clean LHM to fish out the pesky filter :x

I'd say, especially if you're refilling with Hydraflush, once you're all filled up (having primed the pump etc.) do an extended Citaerobics session, turn the wheel from lock to lock etc. to send the stuff round the whole system... THEN bleed all four brakes until you get clean bubble-free fluid coming through. I guess if you wanted, you could take the lid off again and re-check the filters from time to time during the next 2000 miles to see if the Hydraflush has picked up anything on its voyages...

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Post by Stewart (oily!) » Wed Apr 05, 2006 1:11 pm

I have a spare tank and set of filters, I clean them and just swap them over, hydraflush did get a lot of clag out of the system which seems to be gone now (I had the tank off to weld the inner wing and the filters were still clean)
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Post by silverfox » Thu Apr 06, 2006 3:59 pm

Stewart (oily!) wrote:I have a spare tank and set of filters, I clean them and just swap them over, hydraflush did get a lot of clag out of the system which seems to be gone now (I had the tank off to weld the inner wing and the filters were still clean)
I agree it HAS to be done - leave it too long and you'll have a nasty surprise when the steering feels as if its going to lock! I know - it happened to me! Hydraflush worked almost instantly - still got it in - 2,000 more miles to go before replacing.

Thanks for the tip about having a spare reservoir and filters Stewart - great idea! Geoff
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Post by Philip Chidlow » Thu Apr 06, 2006 4:15 pm

Excellent advise, lads. I will try and get hold of a spare reservoir and filters etc - not least because it would allow me to see how it all fits together etc. An super idea.
• 1992 Citroen BX TZD Turbo saloon, White, 94k miles
• 2003 Rover 75 CDTi Connoisseur Tourer, BRG, 145k miles.

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Post by silverfox » Thu Apr 06, 2006 4:25 pm

I find the filters really fiddly when repositioning - also cut my finger first time! Yes is razor sharp Stewart! Is there an easy way/tool to reposition the filters? They are so easy to displace! Need smaller hands - and no wife to badger into doing it for me! :lol:

Also the system seems to take forever to re-pressurise afterwards - I tried the usual steering wheel both ways but still took ages. Priming the pump was difficult maybe I did it wrong? (I removed the supply pipe and primed it with LHM but probably got some air into it!) Geoff
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Post by Way2go » Thu Apr 06, 2006 4:39 pm

silverfox wrote:Also the system seems to take forever to re-pressurise afterwards - I tried the usual steering wheel both ways but still took ages.
There is a component that fails if you operate the power steering without power with the wheels on the ground. That is the rubber flexible coupling to the steering rack and can split. I found this out at a previous MOT time. :(
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Post by Oscar » Thu Apr 06, 2006 5:12 pm

"There is a component that fails if you operate the power steering without power with the wheels on the ground. That is the rubber flexible coupling to the steering rack"

Oh. :( Mine has never had PAS and rebuilding the pinion valve is one of those jobs on the long finger at the moment. This piece of information might move it up the priority list.
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Post by (CZ)enda » Thu Apr 06, 2006 10:56 pm

Do you mean the Hardy joint - the rubber disc? It is not as bad as it seems, it was the first (of many) things I had to fix on my BX. But, it may be I had to saw the old one off :?:
Hydraurincage worked wonders. At least, it made the points that needed proper repair obvious :shock:
The nastiest surprise (the dreaded green puddle below rear axle) actually came before I used the hydraflush.