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LOTS of bubbles from reservoir...

Discussion in 'A3/S3 Forum (8L Chassis)' started by nick4501, Jun 22, 2010.

  1. nick4501
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    nick4501 Member

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    [Jun 22, 2010]
    Hi guys.

    I installed a water temp sensor last weekend and fearing that I'd caused some air bubbles in the system, I took the reservoir cap off and let the engine run until it got up to temperature and the radiator fans came on. Little bubbles immediately starting coming to the top of the water in the reservoir. This continued (extremely quickly - like 3 every second!) for all of the 15 minutes that it took for the car to turn the fans on.

    Now, whenever I turn my car on, I can hear it bubbling away!

    I captured this on my phone (you can hear it bubbling away furiously)...

    View My Video

    What should I do?!
    #1
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  3. Matt82
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    Matt82 Active Member

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    [Jun 22, 2010]
    the water level looks high. does it drop at all?
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  4. nick4501
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    nick4501 Member

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    [Jun 22, 2010]
    I was thinking that myself. When it's cold it's around the middle line on the reservoir case, but it continued to rise as it got warmer. I had to put the top back on, because it was getting close to overflowing after 20 minutes!
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  5. Matt82
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    Matt82 Active Member

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    [Jun 22, 2010]
    well it needs the cap on to pressurise

    if it doesnt pressurise it will boil.

    just put the cap back on, run it normally, itll self bleed anyway, and keep an eye on the water level

    is it a diesel?
    #4
  6. nick4501
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    nick4501 Member

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    [Jun 23, 2010]
    But now when I start it from cold (with the cap on and the bonnet closed), I can still hear it bubbling away!

    No - It's a 2001 a3 1.8t.

    Isn't there a bleed valve that I can play with?
    #5
  7. Alex C
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    Alex C Well-Known Member

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    [Jun 23, 2010]
    you can hear it bubbling with the engine running and the bonnet closed!? you sure?
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  8. nick4501
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    nick4501 Member

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    [Jun 24, 2010]
    Unless it's something RIGHT next to the reservoir - yes!

    I suspect that it needs bleeding properly...it seems to take about 10 mins of driving before the needle even begins to move...
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  9. DenCar
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    DenCar Member

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    [Jun 25, 2010]
    Hi

    Im no expert but, are you sure its bubbling coolent that you can hear? If its not over-heating or losing coolent then dont worry about it, it should be showing 90 degs on your guage when fully warmed up.
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  10. s3dave
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    s3dave TFSI Hybrid

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    [Jun 25, 2010]
    the bubbling is probably in the matrix in the car where the air is trapped, did you have your heater on full when you replaced the coolant? if not do it again with the heater on max
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  11. nick4501
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    nick4501 Member

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    [Jun 25, 2010]
    I know it sounds unusual, but I'm pretty certain it is coming from there!...You can't really see it in the video, but I can see the bubbles! On my last car (Honda CRX), there was a bleed valve at the side of the block. I could simply open the valve until water came out and I knew that the system was air-free. Is there a similar system on A3's?
    #10

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