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Bleeding Coolant System 1.8T

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Cadger, Oct 23, 2011.

  1. Cadger
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    Cadger New Member

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    [Oct 23, 2011]
    Hello all....

    I've just done the coolant flange on the 1.8t engine and I'm unsure if the system is fully bled....

    I've followed all guides I can find on here and various other website but my rad still isn't getting warm....I'll explain what Ive done so far..

    Filled the expansion tank and raised it as high as I can with the lid off and engine running, I've then pulled the one hose almost off the heater inlet until water was shooting up out of the bleed hole. I've then undone the bleed screw on the metal coolant pipe ontop of the inlet manifiold and again water comes out....I've pumped the hoses etc etc and no more air comes out.

    The engine warms up to 90 degrees and stays pretty solid the fan comes on and I'm getting plenty of heat in the cabin without revving it but like I said the rad isn't getting warm and I'm not getting any coolant returning to the expansion tank via the small return pipe....

    Any ideas...I don't want to risk running it if theirs an airlock of some sort in the system.

    Cheers
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  3. CMD
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    CMD Pointing Forward's!!!!!!!!!

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    [Oct 23, 2011]
    Take engine cover off there is a plastic bleed screw (some are metal) on the black coolant pipe unscrew this until air bubbles stop.. The plastic screw can sometimes snap (mine broke) but they are about £1.40 ish to buy from main dealer
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  4. Cadger
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    Cadger New Member

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    [Oct 23, 2011]
    yeah did that bled it until all air had stopped coming out....
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  5. quattro tony
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    quattro tony Member

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    [Oct 23, 2011]
    Did you have any problems b4 you did the coolant flange?, it all sounds ok what u have done, if the heaters are good and the fan comes in, then it sounds not like an air lock problem. Maybe the thermostat is opening early when it shouldn't be. When you are warming it up what do the coolant hoses feel like top and bottom, hot or cold? If both are getting hot then flow must be ok through the rad.
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  6. Cadger
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    Cadger New Member

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    [Oct 24, 2011]
    No problems before hand just the leak from the rear coolant flange....top pipe gets warm 75% along the length but gets cold before it meets the rad, bottom hose is still cold and so is the rad, the fan is coming on but is coooling a cold radiator??
    Last edited: Oct 24, 2011
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  7. Cadger
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    Cadger New Member

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    [Oct 24, 2011]
    Thinking I could have a duff Thermostat which is stuck closed preventing flow down the top pipe and through the rad.....?? Stat has only done 10k fitted by audi but ?!??! I can't think what else it could be.... Top pipe is getting warm but I think thats only through heat conduction rather than flow....
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