FDV : don't just swap it, overhaul it !

Frequently asked technical questions and common modifications/improvements
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DFF53
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Post by DFF53 » Thu Apr 01, 2010 9:18 pm

I dont think , they do, i e-mailed them recently to send one over to New Zealand and they said they dont have them anymore. They still stock Xantia ones though, wonder how different they are?
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TB2
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Post by TB2 » Mon May 10, 2010 2:07 pm

While still searching for a repair kit, I stumbled upon a french site where some guy has posted some nice pictures of the location and removal procedure of the FDV:

http://www.planete-citroen.com/forum/sh ... stcount=15

one of the pictures (removing the radiator...):

Image

Amazing access, when the radiator is gone :D


(but still no luck finding a kit...)
Carl

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1989 16 Valve
---
Parts needed:
- One black leather headrest.
- FDV overhaul kit (95.669.034)
Please contact me through PN if you have any of this.

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Post by themildbunch » Fri Dec 16, 2011 7:18 pm

Just replaced a very leaky FDV on my TD - Been weeping for over 12 months but got bad enough to fail the MOT and cost a 1/2 l of LHM every few weeks!

I got a recon one from Pleiades for about £100 - I now have one good but leaky one and one unknown one to practice reconditioning on....

Not a 5 minute job to change I found... Had to drain and remove the rad, remove acc sphere and remove the starter as one FDV bolt is impossible to access with it in....

I found all pipes went back in with their new seals OK apart from the smaller one which needed a couple if mm cut from the seal... They were all pretty hard to get back in and get the threads started but possible - just make sure you get the pipes in before reconnecting the FDV to the block oh, and clean it all well with degreaser before you start...
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Re: FDV : don't just swap it, overhaul it !

Post by womble3go » Thu Jun 22, 2017 3:33 pm

Hi,

My unit is leaking possible out of the seals just looked at this, is it my computer or are the photo for this missing?

Thanks for the help.

Kevin.

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Re: FDV : don't just swap it, overhaul it !

Post by KevR » Sun Jul 02, 2017 11:15 pm

Photos are missing because they were hosted elsewhere and the thread is incredibly old! I don't think seals are available from Citroen any more, unfortunately.
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

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Re: FDV : don't just swap it, overhaul it !

Post by senmathal » Wed Jul 05, 2017 7:41 am

womble3go wrote:
Thu Jun 22, 2017 3:33 pm
Hi,

My unit is leaking possible out of the seals just looked at this, is it my computer or are the photo for this missing?

Thanks for the help.

Kevin.


The seals can you buy separate every where. It is ordinary O-rings- 4 pc 10x2 mm and one pc 5,5x2 mm for the adjustment screw. Maybe you not need this one. More difficult is the two small filter. They can bee hard to find.

/Mats

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Re: FDV : don't just swap it, overhaul it !

Post by KevR » Wed Jul 05, 2017 8:50 am

That's good information, thanks. Do the seals need to be a specific material? Viton?
I would think the filters could be cleaned very well in an ultrasonic bath.
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

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Re: FDV : don't just swap it, overhaul it !

Post by womble3go » Fri Jul 07, 2017 8:30 pm

Thank you for the reply's on this, I have try a short term fix till I have time to sort out the right way which I saw in a different tread which the person used sealant on the leaking seal which worked for him.

I have tryed this left it to set for 48hr and fired it up today with no sign of leek but see what it does over night?

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Re: FDV : don't just swap it, overhaul it !

Post by senmathal » Mon Jul 17, 2017 6:29 pm

KevR wrote:
Wed Jul 05, 2017 8:50 am
That's good information, thanks. Do the seals need to be a specific material? Viton?
I would think the filters could be cleaned very well in an ultrasonic bath.


You can use the most common type of o-rings as LHM is minaral oil.

The problem with the filter is not dirt, they goes in pieces depending of the high hydraulic pressure. The small pieces than come in to the valve and that`s way it´s very important to disassemble the valve and clean it very careful. But sometimes the filter is OK an you can reuse them.

/Mats

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Re: FDV : don't just swap it, overhaul it !

Post by KevR » Mon Jul 17, 2017 7:28 pm

Thanks - good info!
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

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Re: FDV : don't just swap it, overhaul it !

Post by cauchoiskev » Tue Aug 08, 2017 3:39 pm

I wil try to dig out the original photos and post them again, also for the HP pump thread.

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Re: FDV : don't just swap it, overhaul it !

Post by womble3go » Tue Aug 08, 2017 10:36 pm

It be great if you could.thank you.

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Re: FDV : don't just swap it, overhaul it !

Post by KevR » Wed Aug 09, 2017 1:50 pm

Yes, would be very helpful.
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

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Re: FDV : don't just swap it, overhaul it !

Post by cauchoiskev » Sat Aug 12, 2017 4:26 pm

If you swap your faulty/leaky FDV for one from the scrappers, chances are you'll have the same problem or worse within a year or two.

The repair kit is still available and costs about 20 squid in France, maybe a bit more abroad. Expensive for about 10 grams of plastic (although to be honest I was expecting worse). But, when you've done the overhaul,you've got yourself an FDV as good as new ! Well, almost.

Believe me, it is far easier to overhaul an FDV than to put the bloody thing back on the car, which you would have to do if you simply swap it anyway. However, there are a few things you have to be aware of. A French enthousiast has done 3D drawings of all the innards (although I believe he is mistaken on the quantity and posistion of the springs) :

http://www.planete-citroen.com/forum/sh ... hp?t=36437

1) The two filters (one on top, one on the bottom of the FDV) are held in by 5mm allen screws. The bottom filter is inside a metal holder, which itself is sandwiched between two washers with central holes. Here's the state my two filters were in :
old filters.jpg
old filters
Hardly surprising that the steering was intermittent...

2) Once the filters and one washer are out, you need to get the four plugs on the sides out. WARNING ! don't touch this screw :
dont touch.jpg
don't touch
It regulates the pressure at full lock, and would need special equipment to calibrate.

The plugs are held in by circlips, which look pretty impossible to get out. Here's how you do it :
plug.jpg
plug
You just push the plug back against the spring pressure, and then use a small, sharp screwdriver to prise the circlip out. You'll probably think of a more elegant way of doing it, but this worked. You may have to push the plugs inwards to get out the ones on the opposite side.

3) Take the bottom piston out on the opposite side from the filter (left side, where the spring is, as shown below, which is the FDV as seen from the motor)
explosion.jpg
explosion
because, apparently (a French guy says), the other side is not machined, and would scratch the piston. I can't confirm this, but why take a risk ?

4) Now you can get the filter holder out. Underneath it is an unbelievably thin washer (0.2mm) with an unbelievably small hole in the middle :
thin washer.jpg
thin washer
highly losable, IMO.

5) When it's all apart, wash in petrol. It all looked as good as new, ready for another 300000km ! Buy your kit :

repair kit.jpg
repair kit
which for some reason contains a double ration of LHM joints. Thanks Mr. Citroën !

Then put it all together again : start with the washers, filters and allen screws. The thicker washer has a conical hole, the wider side :
thick washer.jpg
thick washer
should be facing you when you put it in.

Then you can put the pistons and springs in and finish with the plugs. You'll have to push them in again to put in the circlips.

6) Now comes the hard bit : putting it back in the car again ! My advice is not to bolt the FDV onto the motor until you've got the HP pipes on (make sure the cable clamps are undone to give some free play). It might be a good idea to take the radiator and even the accu sphere off. As the Citroën workshop manual says, access is "uneasy".

7) Prime the pump, top up the LHM and say hello to sweet, smooth, non -intermittent PAS ! Hurray !

Footnote : there is a common opinion that the FDV was a bodged solution to avoid referencing a new pump. When you take it apart, it looks very carefully designed indeed. It's amazing what clever folk can do with three springs, two pistons and a ball bearing. IMO, this thing will never fail if the LHM is kept clean (unfortunely, few of us have had our BXs from new...) , it will just start leaking as the joints harden. I would also suggest that an FDV will last at least as long as a 6+2 pump.

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Re: FDV : don't just swap it, overhaul it !

Post by KevR » Sat Aug 12, 2017 7:28 pm

That's great - thanks!
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!