The Benefits of Using Hydraflush

[CitroJim]

In this thread

http://www.frenchcarforum.co.uk/forum/v ... hp?t=22130

Dei asked what the benefits of using Hydraflush were.

Dei, I'm now in a better position to answer after draining my old LHM and refilling with hydraflush today.

When I bought my Activa, I had a look in the LHM reservoir and noted nice green LHM. It had a new HP pump fitted a short while before I bought it and given that nice green LHM that came out of the bleed nipples when I first bled the brakes I thought all was well in the hydraulic department. I was fooled Things were far from well.

I suspected that all was not well when I'd had it a few days but lots of citarobics and new spheres all round and a brake bleed seemed to make things better.

Today I pulled out the filter block on top of the LHM reservoir in preparation to syphon out the old LHM and got the shock of my life. The filters were so badly clogged they were almost invisible. They should be off-white with a fine gauze in them but both mine were a uniform black and each wearing a fur coat I wish I'd taken a photo, it was spectacular! I reckon they'd never been out in the life of the car.

It took me an hour to gently clean them in petrol and to clean the LHM reservoir. It had a deposit of the same muck on its base about a mm thick.

Now, however good you are, when you clean, there is no way you can clean out all the nooks and crannies in the filters and reservoir so it has to be a good idea to run Hydraflush if only to give these items a clean. If that was the state of the reservior and filters, the state of the rest of the system does not bear thinking about

After refilling with Hydraflush and doing a good bout of citarobics and bleeding the brakes the differences became apparant. After only a short time in the hydraulics began working much better. Firstly I noticed how much faster the car rose and fell. It had always been very sluggish in the past.

Out on the road it seems smoother and more like a Xantia should be. Althhough you'll never get a magic carpet ride from an Activa, it is subjectively better and I hope as the Hydraflush works its magic over time it will get better. Even the brakes feel better.

The STOP light also goes out a good deal faster now as well.

All in all a good afternoons work, punctuated by a massive thunderstorm whilst I was safely tucked inside the garage cleaning filters!

I'll leave the Hydraflush in for a 1000 miles and then refill with LHM. I'll be cleaning the filters again too

Just one question. Where does all this muck and dirt come from in what is effectively a sealed system? There did seem an awful lot of it.

A few tips I picked up: The Filter block will not come out of the reservoir unless every pipe is pulled off. I was spoilt on the old TD as the block would easily rise up without disconnecting any pipes at all so I was wrong in what I said in another thread on changing LHM

The pipes will drip for ages when disconnected. As soon as you pull the reservior out, put a suitable drip tray under the pipes if you don't want your gearbox and driveway covered in LHM

The original clips can be re-used with care. Prise them open gently with a very small screwdriver using a twisting motion. Use a small pair of needle nosed pliers to re-clip them. It is easiest to get one side hooked on first and then it'll snap shut.

Petrol is a fantastic cleaner for the filters and the reservior. Take care using it though and use it out of doors!

Those mesh filters are very effective. Despite all the muck and sediment, the LHM I filtered out was crystal clear and clean, if not a little on the yellow side.

LHM does not taste very nice. I need to use something other than Jim Suck Power on my syphon when I come to drain the Hydraflush

I hope it's not toxic

And I still swear at the front caliper bleed nipples. What a silly place to put them

[DickieG]

Quite where all that sediment has comes from would be interesting to find out Jim. All I've ever seen is small particles of rubber hoses and general crud on the numerous Xantia's I've changed the LHM on.

On a similar theme today I connected up a long length of clear hose onto the brake calipers of my Activa to run directly back into the LHM reservior to see if I could flush out any air pockets within the system, but despite allowing it to run for a good two minutes on each caliper with the nipple open there wasn't any significant bubbles. Totally agree on the front nipples, I suppose that makes up for the rear ones being so easy to gain access to on Activa's.

I fitted a nice new shiney front balancing ram today as well .

[jeremy]

Jim - Sorry to say the apparent improvement in your car is probably only new fluid syndrome and in a week or so it'll be back to normal.

A few years ago I had a problem with the FDV on my BX (like someone had assembled it incorrectly with a ball bearing valve the wrong side of its plunger). The system functioned reasonably well but would put the warning light on during the first 5 miles.

I couldn't find what was wrong and kept doing things that I thought might help. Every time I'd loose some LHM, top it up and the problem seemed to have gone away for a couple of days - only to come back again. Eventually I'd clamp the pipe to the pump and not top it up so I could see if I'd made any difference.

A couple of times I've had new LHM in it - seems floaty, rolls more - but generally softer and more comfortable - but each time its gone back to its old ways when the fluid gets mashed up.

[LeeDJC]

The amount of muck that came out when I gave my brakes a quick bleed the other day was most disturbing! Where It comes from I really don't know, but I can only assume that it is a by product of the wear/breakdown of components and seals over time.

With regard to the "new fluid syndrome", my 1.9D had been rather neglected when I got it. However, after a hydraflush (about 3000 miles worth!) and new fluid (plus a change of spheres) it was a transformed car, and still is. That was around 12 months ago!

I reported improvements much like Jim after the fluid change. Smoother ride, MUCH better braking, the stop light going out faster, and the car rising and falling much more smoothly.

Incidentally, this Xantia has, by far, better brakes than ANY other car I have ever driven. They really are fantastic! I just hope that the brakes on my estate are half as good once it's gone through "the change"

[CitroJim]

Incidentally, this Xantia has, by far, better brakes than ANY other car I have ever driven. They really are fantastic! I just hope that the brakes on my estate are half as good once it's gone through "the change"

Funny you should say that Lee, I still think the brakes on my old (non-antisink) TD are far superior. They're sharper, liviler and more responsive than the Activa.

There is nothing wrong with the Activa brakes but they don't feel the same as the old TD. They're actually a lot more progressive and they've got the power but it seems it needs a mite bit more foot pressure to get it.

I guess it is the gradual conventionalisation (i.e. lets make it feel like an ordinary car) syndrome . I had no problem invoking the ABS last evening during testing.

So Lee, I'm sorry, but don't hold out too much hope for your estate brakes feeling like your D brakes

Is your D a non-antisink by any chance Lee?

[DickieG]

Funny you should say that Lee, I still think the brakes on my old (non-antisink) TD are far superior. They're sharper, liviler and more responsive than the Activa.

There is nothing wrong with the Activa brakes but they don't feel the same as the old TD. They're actually a lot more progressive and they've got the power but it seems it needs a mite bit more foot pressure to get it.

I wonder if the dreaded brake spring has been removed on your TD but not from the Activa as that will have the effect you describe above.

[deian]

Thanks for getting back with the 'experience' Jim, I'll be interested to change mine in the next few weeks. Let us know if you feel the 'niceness' disappearing after a week or two as the others have mentioned.

It sounds to me that when all the sediments have been taken away by the hydraflush there may be better 'current' of lhm in the pipes rather than the reliance of 'voltage' for the movement... hence the more responsive brakes and better feeling.

Thanks for that one Jim.

[CitroJim]

I wonder if the dreaded brake spring has been removed on your TD but not from the Activa as that will have the effect you describe above.

Ahh, thanks for reminding me Richard, a very senior moment I must confess I did the spring mod on my TD very early in my ownership and completely forgot that I had

What is more, I've never checked to see if it has been done on my Activa!

I recall it made one heck of a difference on the TD

[DickieG]

Ahh, thanks for reminding me Richard, a very senior moment I must confess

A pleasure Jim, believe me you're not alone with having 'senior moments'

[LeeDJC]

Incidentally, this Xantia has, by far, better brakes than ANY other car I have ever driven. They really are fantastic! I just hope that the brakes on my estate are half as good once it's gone through "the change"

Funny you should say that Lee, I still think the brakes on my old (non-antisink) TD are far superior. They're sharper, liviler and more responsive than the Activa.

There is nothing wrong with the Activa brakes but they don't feel the same as the old TD. They're actually a lot more progressive and they've got the power but it seems it needs a mite bit more foot pressure to get it.

I guess it is the gradual conventionalisation (i.e. lets make it feel like an ordinary car) syndrome . I had no problem invoking the ABS last evening during testing.

So Lee, I'm sorry, but don't hold out too much hope for your estate brakes feeling like your D brakes

Is your D a non-antisink by any chance Lee?

There's no reason they shouldn't be as good TBH. They're both antisink and non hydractive.

[carbon8ed]

Hi chaps - what a forum! just what I needed. My first Xantia estate (N) was one of the first in the country. The brakes were AWESOME so sharp so crisp so good. 1.9TD without air con. NB when you turned the steering wheel I could also here a wooshing sound which was apprently the power steering fluid travelling through a pipe fixed to the bulkhead - really annoying - see later

A year later I 'upgraded' to a 1.9TD with aircon and the brakes seem exactly as people describe, they needed more grunt I felt to get the same effect, the pedal felt softer etc, but they would still stop nonetheless. The wooshing sound has also disappeared too.

I quized the servicing mechanic about this brake difference and wooshing he said that for the wooshing - citroen moved the pipes further away from the bulkhead which stopped the transmission of the sounds into the cabin - for the brakes he said there had been customer complaints about the harshness of the brakes on the early Xantias and that citroen had somewhere installed an additional or alternative pump/plunger system in the braking circuit to soften the brakes up a bit. I am still upset by this to this day.

HTH

[RichardW]

No need to disconnect any pipes to get the filter block out (based on a Hydractive TD with very tight pipes anyway!):

1. Syphon the LHM out of the tank (trying not to inhale - I use a piece of clear tube, you can see if before you drink it then!).
2. Unclip as many of the pipes from the side of the tank as you can
3. Undo the clip and tank bolts and wiggle the tank up a bit, you should then be able to unlip the pipe support from the side of the tank (I seem to remember sliding it forwards or backwards to release it ).
4. You should now be able to wiggle tank right out of the rubber ring at the bottom, and tilt it over about 45° - which leaves enough room to pull the filter block clear of the tank. Remove the tank from the car and put a tub of some sort under the filter block that is now dripping LHM everywhere It's much easier if you've got an assistant at this stage, since the tank falls over when you put it down!

When you re-assemble it's even easier, since the tank will be totally empty and can be reconnected to the filter block at 90°.

I think I had to cut a few cable ties that were holding pipes, and even then some of the small hard plastic pipes pass through the clip.

Considering it's a 2 yearly service item, it's much more awkward than it needs to be - maybe that's why it never gets done!

[LeeDJC]

Hi chaps - what a forum! just what I needed. My first Xantia estate (N) was one of the first in the country. The brakes were AWESOME so sharp so crisp so good. 1.9TD without air con. NB when you turned the steering wheel I could also here a wooshing sound which was apprently the power steering fluid travelling through a pipe fixed to the bulkhead - really annoying - see later

A year later I 'upgraded' to a 1.9TD with aircon and the brakes seem exactly as people describe, they needed more grunt I felt to get the same effect, the pedal felt softer etc, but they would still stop nonetheless. The wooshing sound has also disappeared too.

I quized the servicing mechanic about this brake difference and wooshing he said that for the wooshing - citroen moved the pipes further away from the bulkhead which stopped the transmission of the sounds into the cabin - for the brakes he said there had been customer complaints about the harshness of the brakes on the early Xantias and that citroen had somewhere installed an additional or alternative pump/plunger system in the braking circuit to soften the brakes up a bit. I am still upset by this to this day.

HTH

Thanks for that - that would probably explain the difference in braking between my two then. Very annoying!

[CitroJim]

No need to disconnect any pipes to get the filter block out (based on a Hydractive TD with very tight pipes anyway!):

Thanks for that Richard! Makes good sense I confess I was worried about straining and damaging the tight pipes so I played it cautiously.

Mind you, seeing how much dirt and rubbish was in the fileter block I'm glad I had it out on this occasion to give it a really good clean. Next time though (about 800 miles away) I'll use your method.

Carbon8ed, Welcome! Very interesting. My Activa wooshes a little on full lock but paradoxically my very early Mk1 TD is totally silent

Lee, I'm going to have a look at brake pedal springs this evening and if my Activa still has one (I think it has, it feels like it) I'll try a solid rod and report back. In fact I still have the spring from my TD and it'll be interesting to compare the two. This, carbon8ed, may be what Citroen changed in response to criticism

[CitroJim]

I had a look at my Activa brake pedal and the spring was there so I've replaced it with a piece of 15mm copper water pipe.

The difference is remarkable Sharp, responsive and powerful as hydraulic Citroen brakes should be. They feel just like my TD ones now

I compared the Activa spring to the one from my TD and they're identical.