Citroen CX inlet Manifold vacum leak and heater question
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  1. #1
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    Default Citroen CX inlet Manifold vacum leak and heater question

    Hi All,

    I seem to be finding more and more questions than answers in my quest to get the CX road worthy.
    Upon searching for a LHM leak around the brake valve a came across a small vacuum hose that is connected to the bottom of the inlet manifold

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    this is just sucking the atomsphere. Does this need to be connected to something or am i missing something.

    Also, on the heater/cooler ducting someone had screwed a plate on the vacuum operated valve moving between cold air and something else. What is the something else for?

    And upon all that i think i found the problem of the leak. The oil level reader pipes to the back of the block were frayed etc. after some huffing and puffing these were snipped and fixed. if not this would leak LHM would it not.

    Thanks again for all the Aussie frogs help. Ben

  2. #2
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    Not sure about the vacuum lines, but you can have a significant LHM leak from the LP return piping from the brake valve. There is a T joint there that splits. Have a look at it from the wheelarch, making sure the car is supported properly. I once, and only once, gave myself a big scare under a CX by pulling on the height corrector linkage - asking ... Now what does this do? - then the car dropped onto the wooden blocks I'd placed under it!

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    Fellow Frogger! Fingers's Avatar
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    A timely remind to read the sticky regarding working on hydraulic Citroens......

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    Too many posts! JohnW's Avatar
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    Quote Originally Posted by David S View Post
    Not sure about the vacuum lines, but you can have a significant LHM leak from the LP return piping from the brake valve. There is a T joint there that splits. Have a look at it from the wheelarch, making sure the car is supported properly. I once, and only once, gave myself a big scare under a CX by pulling on the height corrector linkage - asking ... Now what does this do? - then the car dropped onto the wooden blocks I'd placed under it!
    JohnW

    Renault 4CV 1951
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    Renault Scenic 2005 (wife's)
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  5. #5
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    Quote Originally Posted by JohnW View Post
    Absolutely!
    What one does when one is curious and one doesn't really know what one is doing with the benefit of hindsight!

    Maybe, benvv could post a few pictures of the parts being asked about? It's common for people to add vacuum taps and solenoids to cut off the flow to the heater in summer, so what's there may be part of that.

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    Too many posts! JohnW's Avatar
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    Quote Originally Posted by David S View Post
    Absolutely!
    What one does when one is curious and one doesn't really know what one is doing with the benefit of hindsight!

    Maybe, benvv could post a few pictures of the parts being asked about? It's common for people to add vacuum taps and solenoids to cut off the flow to the heater in summer, so what's there may be part of that.
    Yes, I agree totally, to both sentences. "Curiosity killed the cat" it is said! And yes, photos would help, as I didn't understand the question.
    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

  7. #7
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    Citroen CX inlet Manifold vacum leak and heater question-img_1103.jpg
    Citroen CX inlet Manifold vacum leak and heater question-img_1102.jpg

    please see attached the blower intake and how there is a steel plate screwed over the vacuum operated valve. is this the hot air intake that has been blocked up or?


    the main query is what is this vacuum line for? i have taken another picture of an intake manifold to highlight where it is connected to.

    Citroen CX inlet Manifold vacum leak and heater question-img_1104.jpg

    you can see the small nipple where the vacuum line is connected to.


    all comments and assistance greatly appreciated.

  8. #8
    1000+ Posts gerrypro's Avatar
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    That pipe under the manifold is a petrol drain. It is calibrated to only admit a slight amount of air into the induction system. It usually has a tube connected to it that passes any flooded petrol to the under side and onto the road.
    The vac capsule on the side of the heater box should connect via a vac line to the heavy vac line that comes from the console lever closets to the drivers seat. It controls the air re-circulation of the ventilation and air con system.
    Often these vac capsules have a perforated diaphragm and are inoperative. I built one good one up from several different units that each had different faults.
    I have not seen the metal plate before. Maybe some one has performed a repair?
    Cheers Gerry

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    1000+ Posts George 1/8th's Avatar
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    I once had a CX and had that intake unit out of the car.
    I think that metal plate you have there is original, but it's been glued shut somehow. It's supposed to open and close , remote controlled by that little air servo, connected with rubber tubing from the control console.
    If you want to restore it to it's former condition have a look at how it's been glued shut, and cut through the glue. The top of the flap should have a rod which the plate is hinged on. It should open and close.

    That's a known issue with that CX air flow design. Even with the heater tap closed , air coming through the air intake on those cars is always warm. On hot days it's VERY warm. The heater is great in winter, but it's not a very cool car in summer.
    Cheers...George 1/8th.

  10. #10
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by benvv View Post
    Hi All,

    I seem to be finding more and more questions than answers in my quest to get the CX road worthy.
    Upon searching for a LHM leak around the brake valve a came across a small vacuum hose that is connected to the bottom of the inlet manifold

    this is just sucking the atomsphere. Does this need to be connected to something or am i missing something.

    Also, on the heater/cooler ducting someone had screwed a plate on the vacuum operated valve moving between cold air and something else. What is the something else for?

    And upon all that i think i found the problem of the leak. The oil level reader pipes to the back of the block were frayed etc. after some huffing and puffing these were snipped and fixed. if not this would leak LHM would it not.

    Thanks again for all the Aussie frogs help. Ben
    It sounds like you have found the manifold drool tube, leave it unblocked. The oil level gauge will not leak LHM, I have never seen a working one, it's not a part of the hydraulic system. If you wish to dismantle the car back to it's component parts, you could in theory refill the level gauge with LHM so it works. Unless you remove XM dashes just for the enjoyment of it, you'll not get the level gauge working.

    Degrease the entire area with a pressure washer and degreaser and put the car up on ramps, you should them be able to see where it's dripping from. It's likely nowhere near the spot it drips from the car from, the LHM will be running down lines, across cables, down cross members and often on a CX drips from the front height corrector. It is almost unheard of in my experiance for it to be the height corrector that's leaking, it's always something above it.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/citro%EBn-forum/90325-best-project-car-you-have-ever-seen.html
    '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

  11. #11
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by benvv View Post
    Click image for larger version. 

Name:	IMG_1103.jpg 
Views:	537 
Size:	96.9 KB 
ID:	50248
    Click image for larger version. 

Name:	IMG_1102.jpg 
Views:	271 
Size:	99.4 KB 
ID:	50249

    please see attached the blower intake and how there is a steel plate screwed over the vacuum operated valve. is this the hot air intake that has been blocked up or?


    the main query is what is this vacuum line for? i have taken another picture of an intake manifold to highlight where it is connected to.

    Click image for larger version. 

Name:	IMG_1104.jpg 
Views:	567 
Size:	98.0 KB 
ID:	50250

    you can see the small nipple where the vacuum line is connected to.


    all comments and assistance greatly appreciated.
    The metal plate is blocking off the recirculation duct. The car must not have air conditioning, you don't get the recirculation duct unless the car is air conditioned.

    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

  12. #12
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    thanks all for the prompt answers.
    it seemed nonsensical to have a drip tube on the manifold but some how it starts to make sense. yes there is a tube attached to it.

    the blanking plate was screwed on, so presumed it was added after produtcion. the vacuum valve seemed to hold suctions so presumably it still works.
    However with the car running i cannot seem to get a vacuum from the tube that connects to the valve. The tube from the carb is connected so presumably there is an issue with the lever in the cabin. Any thoughts or observations.

    Regarding the leak, got a whole lot of degreaser so on to the area to see if can ascertain a leak. Then took it for a 10min drive to the rust man. no sign of a leak. i think the testing officer is having me on, or the drip was a hangover from the octopus leak that i remedied weeks ago.......



    thanks again ladies and gents.

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    Fellow Frogger! Bruce Llewellyn's Avatar
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    Quote Originally Posted by JohnW View Post
    Yes, I agree totally, to both sentences. "Curiosity killed the cat" it is said! And yes, photos would help, as I didn't understand the question.
    Cats don't have to be curious to get killed by Citroens, just to be asleep when the suspension sinks down.

  14. #14
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    Hi again all,

    1977 CX 2400 Pallas

    On the wiring loom i have found a lead not connected to anything that seems to have sometihng to do with the heating veneliation system. Turning the heater controls changes the voltage present between 5 to 12 volts.

    What would ti be for?

  15. #15
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    the blanking plate was screwed on, so presumed it was added after produtcion. the vacuum valve seemed to hold suctions so presumably it still works.
    However with the car running i cannot seem to get a vacuum from the tube that connects to the valve. The tube from the carb is connected so presumably there is an issue with the lever in the cabin. Any thoughts or

    (The vacuum should work when you pull the heater level all the way back to cold (re-circulate) I can hear a faint buzz from the controls when doing this and the vacuum starts)

    Via the aussiefrogs App
    Citroen C5 II manual '05; C4 Exculsive '07; Citroen CX2200 Pallas '76; CX2400 C-matic Pallas '78

  16. #16
    Fellow Frogger! Jinandfonic's Avatar
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    Quote Originally Posted by benvv View Post
    Hi again all,

    1977 CX 2400 Pallas

    On the wiring loom i have found a lead not connected to anything that seems to have sometihng to do with the heating veneliation system. Turning the heater controls changes the voltage present between 5 to 12 volts.

    What would ti be for?
    This sounds like your interior fan? The resister would change the fan speed therefore the voltage. If it changes on the heater control then this lead would activate the vacuum actuator for the recirculating air flap

    Via the aussiefrogs App
    Citroen C5 II manual '05; C4 Exculsive '07; Citroen CX2200 Pallas '76; CX2400 C-matic Pallas '78

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