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disel leak

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by swarcup, Mar 4, 2010.

  1. swarcup

    swarcup Well-Known Member

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    havent used the car since sunday when i brimmed the tank. im lucky i live only 6 miles from work so i generally cycle and when i returned home this eve straight away noticed a patch of diesel about the size of a tennis racket just in front of the drivers side rear wheel. looking undernieth theres not a lot to see cause its all covered in trim but it seems to be working its way down from near the fuel pipe that connects the filler cap to the tank and dripping from the tank bottom. it wasnt doing it earlier this week im sure i would have seen it. :sadlike:

    any suggestions as to where i should start looking or is it a strip the covers and wing liner off to see. do you think its to full of fuel and i need to burn some off and the problem could be a connection issue.

    weather looks bang on this weekend and im doing a full service so an ideal oppotunity to fix
    anybody had this issue before?
     
  2. quattrojames

    quattrojames Moderator
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    I can't say I've ever experienced this, but down here it's been a pretty sunny (and warm relatively) week, I wonder if the heat has expanded the diesel and it's coming out the overflow?
     
  3. swarcup

    swarcup Well-Known Member

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    i didnt know there is an overflow, if so then that is a feasable thought. il keep an eye
     
    #3 swarcup, Mar 4, 2010
    Last edited: Mar 4, 2010
  4. quattrojames

    quattrojames Moderator
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    Thinking about it. it's probably a breather tube rather than an overflow, but the principle's the same I guess. I'd do a few miles and lose some fuel and see what happens first.
     
  5. simon.m

    simon.m Active Member

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    as stupid as this may sound when i first got my car i filled it right up and see a puddle from under the car.
    now i thought oh iv put to much in so drove home and got under it to find nothing wrong. turns out
    on top of the tank where the float is the 10ins plastic bolt had some how pushed off letting it come out the top of the tank.
    just some food for thought. :icon_thumright:
     
  6. Turkster

    Turkster Bro.Paul 2.5TDI Quattro Sport

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  7. swarcup

    swarcup Well-Known Member

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    Just an update for info purposes

    Acording to an american fuel research web site diesel will expand 1% for every 15 degrees rise in temperature. I reckon the fuel tank is about 60litres so that means 600ml of extra expansion in the tank per 15 degree rise. If the temp rise yesterday was say 8 degrees then that should mean approx 300ml of expansion inside the tank and as my tank was brimming hey presto it had nowhere to go except out of any breathers and onto the floor, has anyone ever noticed that when you fill up after you have left the garage it can run down the outside of the car. this apparently i am informed is due to the fuel warming up in your tank and running out a little breather hole behind the flap as the fuel below ground is quite cold especialy at this time of the year.

    hopefully nothing to worry about then apart from the clean up!
     
  8. simon.m

    simon.m Active Member

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    you learn some thing new every day i was told to fill up in the morning as you get more diesel as its heavier when cold how true that is i dont no:icon_thumright:
    i think its a 70litres tank or so i was told by audi and i think the hanz manul sazs 70 to mate
     
  9. swarcup

    swarcup Well-Known Member

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    THAT SOUNDS TRUE TO ME AS THE FUEL WILL BE COLDER IN THE MORNING SO YOU GET MORE FOR YOUR MONEY
     
  10. simon.m

    simon.m Active Member

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    damm this key bord im in czech for a few days and there z is are y but still says z not y till you hit it :think:
    so will be filling up in the mornings then lol
     
  11. quattrojames

    quattrojames Moderator
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    I was always taught to fill up at night as an empty tank overnight will attract condensation inside. Thats a practical thing rather than a financial thing obviously!
     
  12. simon.m

    simon.m Active Member

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    good point all though i fill up when i need it more than when is best for my pockit lol so not to often on a tdi :icon_thumright:
     
  13. quattrojames

    quattrojames Moderator
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    Pretty often on a 2.5 :cool:
     
  14. simon.m

    simon.m Active Member

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    bet it pulls well though
     
  15. quattrojames

    quattrojames Moderator
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    :thumbsup:
     
  16. Mike B

    Mike B Member

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    I am not sure that the temp in an under ground storage tank will vary much but I learnt a long time ago that filling up and then parking will waste the fuel which is forced out by expansion to air temp .def dont do this on a hot day and lose lots!
     
  17. quattrojames

    quattrojames Moderator
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    The temp in the underground tank is pretty stable yes, but the temp in the cars fuel tank will vary which is where the condensation is formed.
     
  18. swarcup

    swarcup Well-Known Member

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    Burnt off about half of a quater of the tank know and still drip...drip...drip. but its really wierd it only seems to be dripping after a run. i can wipe it up when parked and it wont drip but when ive been on a drive and come home it drips again. over the wekend i removed the rear wheel and arch liner and the plastic cover from undernieth and it is deffinately bone dry around the pipes that deliver the fuel to the tank. it seems to be running from the top of the tank. i couldnt see any of the connections to the tank as the rear diff/exhaust heat shield was obscuring the view. I pulled out the back seat to remove the flap that covers something to do with the fuel tank but a warning sticker said not to remove unless under half full so aired on the side of sense and left alone. What exactly is under the flap? will i be able to remove ok ar should i wait? If you have never lifted the back seat then have a look, my god under mine was 9 years of car life including half a bag of dog biscuits, 2 bungee chords, a generator manual, 21p ,a gold ring, hair clips, somerfield reciepts and what looked like a past diesel spill from the cover plate in question, which is interesting as i wonder if ive had this problem before and it was taken off while full to have a look. if anyone can post a pic or describe what will be seen if removed i would appreciate a lot. thanks and soory for the long and winded update.
     
  19. simon.m

    simon.m Active Member

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    have a look under the hatch in the boot its black and has 3 scrues in it when its up you can see the
    top of the tank where the float is the 10ins plastic bolt holding it in pop off on mine and was leeking from there till i put it back on
     
  20. swarcup

    swarcup Well-Known Member

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    do the screws just hold the plate on? will the other bits be attached to the plate when lifted? just the warning sticker making me a bit twitchy. dont want to get derv in the carpets lol:)
     
  21. simon.m

    simon.m Active Member

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    yes mate if its the flat black plate with ruber around the edeg its just so you can get at the top of the tank where the float is i have a solon so its in my boot behind the seats not under them
     
  22. simon.m

    simon.m Active Member

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    dont thank me yet we mazbe talking about two difront things lol :icon_thumright:
     
  23. quattrojames

    quattrojames Moderator
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    These pics might give you a bit of a clue:

    [​IMG]
    [​IMG]
     
  24. simon.m

    simon.m Active Member

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    so the part i was on about is not the part under the seats but in the boot like i said
    looking at the pic :icon_thumright:
     
    #24 simon.m, Mar 8, 2010
    Last edited: Mar 8, 2010
  25. swarcup

    swarcup Well-Known Member

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    we are talking about the same piece its just mounted in a different poition on a saloon to an avant :icon_thumright:. i opened the triangular cover plate with the 3 screws last night and the fuel is deffinately leaking from the seal around the float switch i believe it is. there is a whitish coloured circular piece of approx 6 inch in diameter with wires and pipes connected to it that drops into the tank,the seal around it is leaking, when driving the fuel is sloshing against it and letting small amounts come out. The seal is compressed down with a large metal retaining washer that twists into some notches. im not sure if i need a new seal or if the tangs on the retaining washer just need a little bend so as to apply more pressure to the seal. The part isnt numbered on james's diagram but is the circular part shown at the right lower position on the diagram
     
  26. simon.m

    simon.m Active Member

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    glad you found it mate.
     

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