CX rear drops right after turning off engine / brake valve?
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Thread: CX rear drops right after turning off engine / brake valve?

  1. #1
    Tadpole
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    Default CX rear drops right after turning off engine / brake valve?

    As the title says, the CX TRD T2 drops the rear almost immediately after turning the engine off. I've replaced the rear cylinders with overhauled ones as well as the rear spheres.
    The accumulator is leaking some LHM from around the "lid" at the top where the tube is clamped on, even though it was replaced with an overhauled one.
    The pump "clicks" every 5 seconds or so.
    All spheres are new, exept at the front wheels. The accumulator sphere has "2004" on it and is supposedly not used.
    The front stays up longer, maybe an hour or two. The rear drops to the ground in 5 minutes.
    Both correctors are replaced with overhauled correctors.
    The (!) lamp left of the engine oil lamp turns on if I brake more than moderately.
    Sometimes the steering is a little heavy when parked, at least just after starting the engine.

    Also, got a leak somewhere around the area of the front corrector or steering rack. Very hard to tell, but it seems it comes from somewhere up there in the jungle...

    I've heard rumours about the "brake valve", but I don't know what to look for or how to overhaul it. But I bought an overhaul kit for it.

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    Is there anybody on the forum that has any experience with similar issues?

    Thanks, J.

  2. #2
    Real cars have hydraulics DoubleChevron's Avatar
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    Yeah, the bit your brake pedal pushes on. The pressure source for the rear brakes is the rear suspension circuit. So if the brake valve starts leaking internally, the rear suspension will drop quickly. I think they must have changed the design when they started making BX's .... as the early brake valves never did this.

    seeya
    Shane L.
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  3. #3
    Tadpole
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    Okay, thanks. Is there any point using the overhaul kit, with new seals and stuff, or is the hardware probably worn out?

  4. #4
    Too many posts! JohnW's Avatar
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    I'd be looking at the accumulator in parallel with fixing the brake valve - even if not used much, 14 years is quite a long time for a sphere.

    You know about places like CX-Basis for spare parts?

    Good luck.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
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  5. #5
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by JohnW View Post
    I'd be looking at the accumulator in parallel with fixing the brake valve - even if not used much, 14 years is quite a long time for a sphere.

    You know about places like CX-Basis for spare parts?

    Good luck.
    The rear suspension is the brake accumulator for the rear brake circuit. Even if you have massive spectacular hydraulic failure, you will still have rear brakes while you have rear suspension height. I've found this a couple of times in an ID19 if I keep driving with the pressure light on.

    Leaking doseur valves are the issue.

    http://citroen.tramontana.co.hu/en/b...re/brake-valve

    seeya,
    Shane L.

    seeya,
    Shane L.
    JohnW likes this.
    'Cit' homepage:
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    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  6. #6
    Tadpole
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    Thanks. I read the article. So there is no point overhauling the brake valve,

    would you recommend buying a brand new from CX Basis?

    When I think about it, if the pressure escapes to rebound constantly, no wonder that the pump ticks so often...

  7. #7
    Too many posts! JohnW's Avatar
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    I've had many good experiences with CX-Basis, if that is your question. I've no experience repairing one, so can't honestly comment - Shane has so much more experience.

    Good luck with it. Not the most conveniently located component to change!
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  8. #8
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by jupan View Post
    Thanks. I read the article. So there is no point overhauling the brake valve,

    would you recommend buying a brand new from CX Basis?

    When I think about it, if the pressure escapes to rebound constantly, no wonder that the pump ticks so often...
    I just try a used one from an earlier CX .... They the brake valves on seem to become a problem when the BX came along.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  9. #9
    1000+ Posts George 1/8th's Avatar
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    Hey Jupan,
    many of us here have owned Cxs and done all of those jobs. Shane and John and a few others know just about all there is to know . I restored a CX for as a hobby for about 2 years before I registered it and drove it. As a general rule , if your accumulator is cycling about every 5 seconds you have a pretty flat Accumulator sphere. Have a good look at it. Depressurise the system, unscrew the accumulator sphere, make sure it is an accumulator sphere, ie. one with a large centre hole and no baffles. It shouldn't act like a fire extinguisher when you take it off. If it does, it's dead.
    I'd begin by replacing it with a tested one or a new one. You could get one from a wrecker for about $10.00. Or a new one for about $100.oo
    Have a good look all around the steering rack. There should be no leaks. If there is LHM running out of it , you will have to remove it , dismantle it, and replace all of the o rings and seals and wipers. Mine took all day, but was worth it.
    The seal kit cost me about $200.00 about 13 years ago. You'll probably have to get one from the UK.
    Good luck.
    JohnW likes this.

  10. #10
    1000+ Posts gerrypro's Avatar
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    Quote Originally Posted by George 1/8th View Post
    Hey Jupan,

    Have a good look all around the steering rack. There should be no leaks. If there is LHM running out of it , you will have to remove it , dismantle it, and replace all of the o rings and seals and wipers. Mine took all day, but was worth it.
    The seal kit cost me about $200.00 about 13 years ago. You'll probably have to get one from the UK.
    Good luck.
    CX basis has seal kits and just about everything else you need for a CX!
    I agree with everything that George has said and would follow his suggestions before removing the brake valve. Then if that does not solve the problem perhaps the brake valve could be investigated. Which ever way you will end up with a system that is as good as it gets. Not a bad thing to achieve on a 40 year old car.
    BTW I have done all of this myself.
    One plus for you is that Jochen Heusel at CX basis will only have to post the bits to Norway from Germany! Not all the way out to Australia. Should be quite quick and much less expensive!
    Cheers Gerry

  11. #11
    Too many posts! JohnW's Avatar
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    For your own information, get out the kitchen scales and weigh the accumulator when it comes off and weigh the new one (I'm expecting) before you fit it. Should be about 400 g difference if the old one is dead, as it will be full of LHM not nitrogen!

    Just a thought.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  12. #12
    1000+ Posts gerrypro's Avatar
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    Quote Originally Posted by jupan View Post

    would you recommend buying a brand new from CX Basis?

    ...
    Yes. Well worth the investment.
    Cheers Gerry

  13. #13
    Fellow Frogger! citroenthusiast's Avatar
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    Quote Originally Posted by jupan View Post
    As the title says, the CX TRD T2 drops the rear almost immediately after turning the engine off. I've replaced the rear cylinders with overhauled ones as well as the rear spheres.
    The accumulator is leaking some LHM from around the "lid" at the top where the tube is clamped on, even though it was replaced with an overhauled one.
    The pump "clicks" every 5 seconds or so.
    All spheres are new, exept at the front wheels. The accumulator sphere has "2004" on it and is supposedly not used.
    The front stays up longer, maybe an hour or two. The rear drops to the ground in 5 minutes.
    Both correctors are replaced with overhauled correctors.
    Thanks, J.
    Where did you source the overhauled height correctors? Unless it was Citrotech, the overhaul may have simply been replacing the rubber bits. That means there still may be massive internal leakage (loss of pressure) even though there are no further external leaks (dripping, etc.). Does the rear stay up longer if the manual valve is put in its highest position before you shut off the engine?
    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

  14. #14
    Tadpole
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    Quote Originally Posted by citroenthusiast View Post
    Where did you source the overhauled height correctors? Unless it was Citrotech, the overhaul may have simply been replacing the rubber bits. That means there still may be massive internal leakage (loss of pressure) even though there are no further external leaks (dripping, etc.). Does the rear stay up longer if the manual valve is put in its highest position before you shut off the engine?
    I tried that theory, but it drops just a quickly... But, if I hoist it to the highest position, it stays there for a while.

    My question about overhauling the brake valve with the kit was about whether that would solve it og if the hardware in the brake valve itself normally just wears out so that it wouldn't help to use the overhaul kit.

    The brake valve costs almost 500 euros so that's why I asked if it's worth it...
    Last edited by jupan; 2nd August 2018 at 10:34 AM.

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