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Air filter preheat system

Discussion in 'Bay Tech Clinic' started by Klaus Schroeder, Sep 29, 2021.

  1. Klaus Schroeder

    Klaus Schroeder Member

    Messages:
    65
    Location:
    Victoria
    preheat 1.gif preheat5.JPG preheat8.JPG Hi All,
    I have a late 74/75 2 litre bay.

    Just enquiring whether some one can explain the purpose of the preheat system, air regulator box attached to the air filter. It appears my system may have been disconnected ? The left hand side is ok from the air filter to carb. The right side at the top of filter has been disconnected , why would someone do this ,would there be a purpose. ?

    From the photos and diagram I am enquiring about 13,14 and 15 where does number 15 connect to? I don`t have number 17 either .

    Regards Klaus
     
    Last edited by a moderator: Sep 29, 2021
  2. tintop

    tintop Well-Known Member

    Messages:
    1,043
    Location:
    Canberra
    Hi, 13,14 &15 aren't part of the pre heat system they are part of the fuel breather system.

    The small pipe on the left side carby is part of the central idling system

    Preheat system cuts out once the engine has warmed up - then instead of taking warm air from the engine it takes cool air via 17 which should head over above the battery
     
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  3. Klaus Schroeder

    Klaus Schroeder Member

    Messages:
    65
    Location:
    Victoria
    Ok, that makes sense now. So , my lfuel breather system is not connected ,therefore I should connect to the top nipple of air filter with a rubber hose to where does it go??
    Back to preheat system are there any connections I should see? I think,last time I checked a flap is inside? if so, how does this open or close? Am I on the right track here?
    I shall buy a no. 17 tube and connect
    Regards Klaus
     
  4. tintop

    tintop Well-Known Member

    Messages:
    1,043
    Location:
    Canberra
    There should be fuel tank breather hoses coming from both sides (up high) along the back of the engine bay which go into a tee and then to the air filter.

    There should be a vacuum hose that comes from under the air filter box and goes to the left hand fitting on the right hand carby air intake...the right hand fitting should have a hose going down to the pre heater
     
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  5. Klaus Schroeder

    Klaus Schroeder Member

    Messages:
    65
    Location:
    Victoria
    preheat10.jpg
    Thanks Tintop, I think I got this ,I will need to follow your notes and check this out. Attached is a photo of the left side airfilter connection it looks ok to me .
     
  6. tintop

    tintop Well-Known Member

    Messages:
    1,043
    Location:
    Canberra
    Yep, left side is just the central idling system
     
  7. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    3,012
    Location:
    Penna, Hobart
    The vapour line hoses go to the top right on the filter which is the one blocked off in you top photo. The 2 nipples we are talking about is on the other side and underneath. The one under the filter is under the middle of the filter and if you take the filter box out you will see it has three large tubes joined in the middle with a smaller tube off it facing toward you. May be blocked off but it shouldn't be.

    Here is a link to the carb tuning post and it has a diagram of all the pipes (and some only the Americans have.) I just noticed the 3 pipe connection under the filter in the picture (blue) has a 4th running back toward the fan housing but that wont be on yours.

    https://forums.kombiclub.com/thread...pe-iv-adjustment-procedure.45512/#post-488549


    Adrian
     
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  8. 1500king

    1500king Well-Known Member

    Messages:
    1,683
    Location:
    Adelaide, SA
    No such thing as a pre 76 2L bay. August 1975(1976 model year) was first of the 2.0L. Yours likely 1800
     
  9. 1500king

    1500king Well-Known Member

    Messages:
    1,683
    Location:
    Adelaide, SA
    I have all of those in stock. @volksdoktor
     
  10. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    3,012
    Location:
    Penna, Hobart
    It is likely if you actually have a 2l in your 74/75 it is a replacement engine (really common after 45+ years).

    Adrian
     
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