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How do you bleed the air out of the cooling system?

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by gadgesxi, Jan 15, 2010.

  1. gadgesxi
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    gadgesxi Member

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    Think i have an air lock in my system, but anyway at the weekend I'm going to try and blast my heater matrix clean with the garden hose pipe and then top the system up and bleed.

    I had a little go last night, not sure if i done it correct though. I took the cap off the cooling water tank, reved car to 3k, next thing eruptions out the water tank, **** myself and turned engine off, then the tank sucked its self clean nearly.

    Also noticed a screw on the solid pipe that runs accros the top of the engine, i unscrewed this slighlty and water was bubbling out, didnt want to take the screw out incase it was under pressure and blew off everywhere.

    So, how do i do it?
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  2. pjmspeedy
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    pjmspeedy Dude, what's mine say ?

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    The little screw that you mentioned is the bleed screw so carry on as you were but leave the engine ticking over.
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  3. gadgesxi
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    gadgesxi Member

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    and keep the cap on the water tank?
    Do i start the engine with the bleed screw removed?
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  4. technics100
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    technics100 Member

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    Run the car upto temperature and have the heater on max heat and power inside, fill until it won't take any more then rev the engine, if its upto temp the thermostat should open and it should swallow some coolant fill it up. I had my water pump done during the week and the mechanic said it was a pain to bleed the system. Where abouts if the bleed valve?
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  5. gadgesxi
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    gadgesxi Member

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    thanks for the help
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  6. defsix
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    defsix Member

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    Where is the drain plug for the radiator ? is it the plastic tap on the bottom ride side of the radiator , along the pipe a few inches ?
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  7. gadgesxi
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    gadgesxi Member

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    Can anyone tell me how to bleed the cooling system on the 1.8t engine please? Gonna have ago at doing this today.
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  8. Rhencullen1989
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    Rhencullen1989 190 S LINE QUATTRO

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    You really need to fill up the expansion tank really slowly with a 50/50 mix of de-ionised water and G12+, on the B5's you need to unbolt the expansion tank and hold it as high as possible, i assume the B6's are the same. There is a bleed screw on the metal pipe that runs the length of the engine under the plastic cover, remove this screw and slowly fill till coolant comes out and no air. There also may be a bleed hole in the rubber pipe that goes into the heater matrix, loosen the hose clamp and slide the rubber pipe off until the small bleed hole in the rubber pipe is clear of the stub on the matrix, do not remove the pipe all the way, just an inch or two. Have a go at that and see how you get on.
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  9. gadgesxi
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    gadgesxi Member

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    All sorted. Took half the day messing about and pushing the air out, but got there in the end :)
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