More ds21 woes
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Thread: More ds21 woes

  1. #1
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    Icon5 More ds21 woes

    I have recently had a rear brake cylinder apart to fit new o-rings. I re-pressurised the system to check for leaks at the connection when my friend near the front of the car saw a rapidly widening pool of LHM from under the left front. I soon discovered that there was a major leak ( more like a torrent) from the larger connection to the brake accumulator. This seemed odd as I had done nothing in that vicinity. So I proceeded to change the seal. Same result. Try again - I loosened the accumulator hold-down bracket as it had been difficult to get the pipe centralised so that the end would fit into the shallow centralising recess. Same result. What the...

    I see 2 possible explanations - that the seal is not the correct size (although it is identical to the old one) or that there is a split in the pipe towards the end. (the LHM gushes out between the pipe and the screw in fitting)

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    The seal is about 10mm OD x 10mm long. Should it be longer? as when I screw the fitting in it stops against the bulge in the pipe without the usual feeling of 'crush' which the rubber seal gives first.

    Any ideas most welcome, Don

  2. #2
    Fellow Frogger
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    There are two large seals I've encountered. One is thicker than the other. The parts book shows two larger seals which are both 9.5mm long with 6.8mm ID, but the OD is either 10.2 or 11.8mm. I think you want the large one at the brake accumulator. It turns up in the CX remote brake sphere too.
    https://www.franzose.de/en/Citroen-D...ulik/ANR32277/
    They note:
    Hydraulic line rubber 6,35mm. LHM (green). 12mm outside diameter. About
    10mm long. Only suitable for Citroen DS + SM, with LHM hydraulic system.
    This heavy rubber is for the connection at the brake system accumulator.


  3. #3
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    Thanks David. I think that's it, I need a bigger seal. The old one appears to be a 10mm diameter one and managed to work for about 6 years until it got tired of doing a man's job!

    Don

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    I managed to get the correct(larger diameter) seal locally. Initially it still leaked profusely but after a bit more tightening it leaks only a little.
    HOWEVER - now there is another leak. After running the engine for a minute or two there is a strange smell and smoke appears from below the exhaust manifold. Investigation revealed green fluid dripping off the flange at the end of the downpipe and also running down the front of the downpipe just below the pipe to manifold flange. This is where the smoke comes from but where is the leak?
    A friend and I have checked all the hydraulic devices and pipes anywhere near the exhaust downpipe and found no clues. I am totally mystified.
    Tomorrow I will check further. Does anyone know what burning coolant and or LHM smells like?

  5. #5
    Administrator GreenBlood's Avatar
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    Quote Originally Posted by tresbon View Post
    I managed to get the correct(larger diameter) seal locally. Initially it still leaked profusely but after a bit more tightening it leaks only a little.
    HOWEVER - now there is another leak. After running the engine for a minute or two there is a strange smell and smoke appears from below the exhaust manifold. Investigation revealed green fluid dripping off the flange at the end of the downpipe and also running down the front of the downpipe just below the pipe to manifold flange. This is where the smoke comes from but where is the leak?
    A friend and I have checked all the hydraulic devices and pipes anywhere near the exhaust downpipe and found no clues. I am totally mystified.
    Tomorrow I will check further. Does anyone know what burning coolant and or LHM smells like?
    My best guess would be a coolant leak from the steel heater pipe that runs above the exhaust manifold along the head, maybe at the connection to the head, or possibly the rubber hose it connects to at the rear - are you losing coolant?

    Cheers
    Chris
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    Thanks Chris. There is no leak from the coolant pipe or attached hose, but, mysteriously the leak onto the exhaust downpipe has now ceased. That is good but I now have a new leak (a steady drip of LHM) from the other side of the car in the vicinity of a junction between the underside of the floor panel and the front of the cross member under the engine. Once a gain I cannot tell from where it originates. I guess it could be from the height corrector so will take the guard and panel off to get a view.
    Just a thought - is it possible that the hydraulic pressure could be too high thus causing all these odd leaks?

    Don
    Quote Originally Posted by GreenBlood View Post
    My best guess would be a coolant leak from the steel heater pipe that runs above the exhaust manifold along the head, maybe at the connection to the head, or possibly the rubber hose it connects to at the rear - are you losing coolant?

    Cheers
    Chris

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    1000+ Posts gerrypro's Avatar
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    When fitting a steel hydraulic line the very tip of the pipe is meant to fit snuggly into the bore of the casting. It is possible to deform the tip of the pipe through careless fitting to the point that the tip develops a burr preventing it engaging fully into the casting. Turning the union nut up tight behind such a badly fitted pipe will not create a proper seal and will wholly rely on the pipe seal, which may or may not serve to seal the joint. Carefully inspect the tip of the pipe to ascertain its condition. Remove any burring with a fine metal file and refit without the seal, making sure that you feel the engagement deep into the casting of the hydraulic unit, and that the pipe sits concentrically with the bore of the threads. There is no need to do up the union nut at this stage. Remove the pipe and then fit the seal making sure the pipe fits as before. You will probably notice that the union nut will fit deeper than it used to and that there will be a noticeable squash on the seal. If this is the case the union will only need a moderate tightening.
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    Cheers Gerry

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    1000+ Posts forumnoreason's Avatar
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    that leak onto the downpipe could be from front suspension cylinder, also the leak on left same, boots could be split (old?) If you cannot see any obvious leaks with motor running on high setting with a lamp then you might have to remove the wing and hydraulic cover plate to see where the issue is.

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    Thanks for that Jerry. As it happens, when I was trying to get the pipe into the brake accumulator to seal I noticed that there was small burr on the pipe end which I removed. So that was probably the problem at that time but was probably caused by my attempt to refit the pipe when it was not properly aligned with the unit. I had never thought that the pipe fit into the bore was so critical but I did wonder how that little bit of rubber sealed against the high pressure.
    Quote Originally Posted by gerrypro View Post
    When fitting a steel hydraulic line the very tip of the pipe is meant to fit snuggly into the bore of the casting. It is possible to deform the tip of the pipe through careless fitting to the point that the tip develops a burr preventing it engaging fully into the casting. Turning the union nut up tight behind such a badly fitted pipe will not create a proper seal and will wholly rely on the pipe seal, which may or may not serve to seal the joint. Carefully inspect the tip of the pipe to ascertain its condition. Remove any burring with a fine metal file and refit without the seal, making sure that you feel the engagement deep into the casting of the hydraulic unit, and that the pipe sits concentrically with the bore of the threads. There is no need to do up the union nut at this stage. Remove the pipe and then fit the seal making sure the pipe fits as before. You will probably notice that the union nut will fit deeper than it used to and that there will be a noticeable squash on the seal. If this is the case the union will only need a moderate tightening.

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    Thanks for that idea. My next task is to do as you say. The new drip is clearly from some part of the leakage return system. I have had new front boots ready for some time, just waiting for the motivation to use them! Don
    Quote Originally Posted by forumnoreason View Post
    that leak onto the downpipe could be from front suspension cylinder, also the leak on left same, boots could be split (old?) If you cannot see any obvious leaks with motor running on high setting with a lamp then you might have to remove the wing and hydraulic cover plate to see where the issue is.

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    Trace the piping and hoses back from the bottom of the reservoir and you see they run along the left side of the engine bay. There are some short rubber joiners under the reservoir and some longer hoses along the left side of the engine bay. There is also a short hose right in the corner made by the left chassis rail and the main crossmember, joining the return pipe running across the crossmember to the piping along the left chassis rail. It's hard to see with the undertray on, but it eventually perishes and leaks a lot as it brings all the left side return flow back to the reservoir.

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    I have had the left guard and the panel behind off and there was no sign of any leaks in there. I eventually traced a minor leak of green fluid back to the heater radiator. That was surprise because the coolant feels quite 'oily' and I thought I had a LHM leak. They are both exactly the same color too.
    On the other side, where there is intermittent leakage onto the exhaust pipe, it appears that it is LHM coming from the lower side of the joint in the 2-piece sphere. I don't think I have read or heard about this fault before. I assume that I need a new sphere?

    Don

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    Fellow Frogger! mberry's Avatar
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    I doubt you'll need a new sphere. I would expect that it wasn't properly tightened when reassembled. Maybe the thread wasn't cleaned properly..... either way, most likely repairable, I wouldn't discard a 2 piece sphere.

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