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Facelift Coolant leak around bottle

kpm278 Aug 11, 2018

  1. kpm278

    kpm278 Member

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    Hi

    I have a 2014 tdi 2.0 that intermittently empties its coolant bottle. I can see coolant around the bottle/engine mount area and on the bottom engine cover/splash shield. I removed the pipes and bottle and looked for splits but all good. I filled it back up and monitored and it stayed level for a couple of days until tonight when it emptied again.

    I’ve read caps can go naff and is a straightforward replacement obviously. Is there anything else common I should look at?

    Thanks
     
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  3. B5NUT

    B5NUT Well-Known Member TFSI Owners Group VCDS Map User Audi A6 Audi A3 Audi Avant Owner Group quattro S-line owners group S tronic

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    Most likely the system is over pressurised and it's emptying the coolant out that way. Go for a drive and see how much pressure is in the system, the coolant pipes should have a good amount of pressure but if they are rock hard then somehow excess pressure is getting into the system. This could be down to waterpump, stat or even head gasket.
     
  4. kpm278

    kpm278 Member

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    Thanks for the info. Did 175 miles without really losing any, but then noticed a bit around the bottle after another 30 miles. Coolant pipes were still squishy after 175 miles. Next step I’ll wrap some tissue around the ends of the pipes and under the bottle and see what gets wet first.

    Water pump was changed a couple of months back. I noticed they didn’t fasten one of the pipe clips back on but made no difference when I fixed that.
     
  5. kpm278

    kpm278 Member

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    Had been fine for 500 miles but got back in the car 12hrs after a 40 mile run up the motorway and coolant bottle was empty. It’s definitely coming out the hole under the tank which does indicate pressure increase as suggested. It’s also not dropping over time but suddenly. Would a garage able to pressure test something that apparently happens randomly and at great intervals?
     
  6. AlS3BE

    AlS3BE Well-Known Member

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    You will probably find it’s not random.
    Most likely when the car is under hard boost that’s when it’s likely to start leaking.
    I remember from an old tunes Subaru that the radiator cap was rated to 1.1 bar and as soon as it was boosting it was coming out the cap at a rapid rate. Changed the cap to a 1.3 bar and all was good. Not sure if this applies to the a3.
     
  7. kpm278

    kpm278 Member

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    update. been driving the car a bit harder recently but no leak. car is in the garage now, they pressure tested and all is fine. they said one of the hoses has noticeably more crystallisation around it, indicating concentration of coolant and suggest i replace it at £156. that sounds like a bit of a stab in the dark considering the coolant is emptying out the hole at the bottom and not the hose. i'm inclined to not replace the hose at this point, any thoughts?
     
  8. kpm278

    kpm278 Member

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    been looking around and come across a couple of threads indicating coolant leak when a certain set of parameters are met:

    dpf regerenation
    +
    coolant at operating temperature
    +
    certain speed

    https://www.briskoda.net/forums/topic/446946-coolant-lost-during-dpf-active-regeneration/
    http://forums.tdiclub.com/showpost.php?p=5379013&postcount=9

    is there any way to tell when regeneration is taking place? i've never noticed a light on my dash or unusual sound.
    i have vcds now so perhaps i can test the theory with a forced regen
     
  9. Svenedin

    Svenedin Well-Known Member Team Navarra Audi S3 quattro S tronic

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    Maybe try a replacement cap. Cheap fix if that's what it is. My coolant leaked out of the top but that is because Audi overfilled it when they serviced the car. It didn't empty the bottle though. You've checked hoses for splits but what about the security of any clips? It passed a static pressure test but that isn't at operating temperature. If Audi is saying a hose has crystallisation around it are they saying it is blocked? You could take it off and clean it out. I believe draining the cooling system is problematic though as it is supposed to be filled back up under vacuum so that there isn't air trapped in the system (at least on my engine)
     
    Last edited: Sep 6, 2018
  10. kpm278

    kpm278 Member

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    Managed to get the warranty company/ dealer (not audi) to cover the cost of the hose so i'll let it be replaced. no residue around the cap when it leaks (it all comes out the bottom) so i'm thinking the cap is sound, but for the sake of £10 (or whatever it costs) that will be my next fix if it happens again, alongside vcds regen. i'll also ask the garage if they pressure tested it with a warm engine. thanks for input all
     
  11. kpm278

    kpm278 Member

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    Car has been running sound for the past 5-6 weeks, no sudden loss of coolant. Checked today while under the bay and coolant level is sitting on the lower marker level now and I can feel slimy coolant under the tank. So it's lost a cupful. An improvement I suppose.....
     
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