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Inexplicable coolant loss???

Discussion in 'A4/S4 forum(B5 Chassis)' started by Arrkon, Aug 7, 2011.

  1. Arrkon
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    Arrkon Midlands regional Moderator

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    Im losing coolant from somewhere (fill it on Mon morning, by the end of the week it's down to min. Has dropped so far at occasionally that the DIS warning comes on).... no idea where to start looking though.
    • HVAC works great hot and cold.
    • Coolant temp never above 90, and doesnt move...
    • No apparent leaks
    • No white smoke/steam
    :think: any suggestions where to start looking?

    Car is a 1.8T APU, and G12 is getting expensive with the amount ive gone through :(

    (on a side note also, how much oil should a 1.8T go through/lose?)
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  2. Oranoco
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    Oranoco Well-Known Member

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    Check the plastic pipe at the back of the engine and for signs of leaking on top of the gearbox
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  3. ScottD3
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    ScottD3 I want your faulty electronics

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    How's your carpets?
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  4. B5NUT
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    B5NUT Well-Known Member

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    Have you checked the expansion tank overflow? I had the similar fault on my TDi and it turned out to be he head gasket, exaust gasses going into the coolant system and it was being chuck out the expansion tank.
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  5. Arrkon
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    Arrkon Midlands regional Moderator

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    Carpets, bone dry. Gearbox was out only a few weeks back to do the clutch conversion, no obvious signs on or around that. Expansion tank "overflow" I've not looked at, will check that when I get a chance. Though the header doesn't smell "exhausty" even after a thrashing, just smells of g12 lol
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  6. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Easy way to check is get someone to use an emissions tester over the header tank that will rule out the headgasket.
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  7. THE MONSTER
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    THE MONSTER Member

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    I presume you have your under tray on have you checked to see if that is full of water or any water in it lowest point and all that..

    That amount must be visible and going somewhere..
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  8. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Also check for a pink crusty residue of coolant on the system also near the water pump and at the oil cooler pipes !
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  9. Sandip
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    Sandip Active Member

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    I had this on my S3, put some red food colouring into your coolant, go for a drive, then pull you plugs out one at a time. If the ceramic on any of the plugs has turned pink then you may possibly have a hairline crack on the cylinder head.

    Or like Bradderz says, hydrocarbon test the coolant
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  10. salad.dodger
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    salad.dodger Member

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    I had coolant lose on a 5 series BMW, works out the head was leaking right at the back, could see water marks
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  11. B5NUT
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    B5NUT Well-Known Member

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    A very easy test to check if your getting exhaust gasses into the coolant system would be to take it for a quick drive and get the engine almost upto temp and check the hoses for pressure, if they are solid then gasses are getting into the coolant system, and you are looking at either a HG failure or damage to the cylinder head.

    The top water hose on my car was just about solid even after a quick drive and the engine was around 80 on temp.

    One other possible cause is the expension cap has failed and needs to be replaced, a quick pressure test would answer that question or just get one from a breakers for a couple of quid.
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  12. Arrkon
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    Arrkon Midlands regional Moderator

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    Ah well i have just squeezed the hoses and they are still quite soft :) so hopefully not a HG problem
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  13. tdia4
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    tdia4 TDIPOWARRR

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    Leaking from a Core plug maybe?
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  14. Mike B
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    Mike B Member

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    Take off the header tank and check at the back for acrack.This is where we found a leak and the new tank was £12
    #14
  15. Arrkon
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    Arrkon Midlands regional Moderator

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    How do you mean a "core plug" ?
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  16. ScottD3
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    ScottD3 I want your faulty electronics

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    Round metal disk pushed in to the side of the engine. It Blocks up the old holes used during the manufacturing process.
    They can become thin and leak (happened on my land rover) or fall out.
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  17. bmarshall
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    bmarshall Member

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    Welsh plug
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  18. Arrkon
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    Arrkon Midlands regional Moderator

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    After having a good look, i may have found the issue...

    Take a peek at the pics on FLICKR and tell me what you think... its like a pinky white sticky paste.... could be some coolant residue?

    Cheers guys...
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  19. ScottD3
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    ScottD3 I want your faulty electronics

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    Yup, I'd say thats coolant.
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  20. Arrkon
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    Arrkon Midlands regional Moderator

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    thought so... have added a diagram of the area with positions i think the leak may be coming from... any ideas? I suspect No 3 is at fault... or hopefully duff pipes...
    Last edited: Aug 16, 2011
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  21. ScottD3
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    ScottD3 I want your faulty electronics

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    it looks like its coming from coolant pipes on number 14 of your diagram.
    Possible a split pipe or the metal pipe work in side has rotted away.

    I'd take the coolant pipes off, give the area a good old clean, replace the spring clips and try again.
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  22. Arrkon
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    Arrkon Midlands regional Moderator

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    yup was thinkin that... Cheap fixes win :w00t:
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  23. ScottD3
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    ScottD3 I want your faulty electronics

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    Deffo.

    I just need to find out where my coolant smell is coming from now.
    I'm off to check my oil filter housing.
    #23
  24. Arrkon
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    Arrkon Midlands regional Moderator

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    if its strong interior smell. could be the HVAC exchanger.
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  25. ScottD3
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    ScottD3 I want your faulty electronics

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    I do hope you don't mean this
    [​IMG]
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  26. Arrkon
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    Arrkon Midlands regional Moderator

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    yep thats what i meant... is that pic yours???
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  27. ScottD3
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    ScottD3 I want your faulty electronics

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    Nahh Google image.
    I hope its not.
    I really don't want to take my days out.
    #27
  28. Arrkon
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    Arrkon Midlands regional Moderator

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    Days? Did you mean dash??? Haha
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  29. ScottD3
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    ScottD3 I want your faulty electronics

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    LOL.
    Yeah Dash.

    The fact that it only smells when it pumps out warm air has me even more worried now.

    Know of any other way to check it?
    All my carpets are dry.
    #29
  30. Arrkon
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    Arrkon Midlands regional Moderator

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    Pressure test maybe?
    #30

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