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electric vacuum pump

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by gaz238, Mar 30, 2007.

  1. gaz238
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    gaz238 New Member

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    [Mar 30, 2007]
    vag com is giving 17787 - brake boost vacuum system. my vehicle is an a6 2.0 petrol cvt is fitted with an electric vacuum pump which they fit to automatics, not sure why. i think it gives additional vacuum to the servo. it is located next to the power steering fluid. i believe this to be the cause of the problem as if i disconnect it from the hose and press the brake pedal, there is no response from it at all - no vacuum/noise etc. unless it`s the electrical connection? if this was the case i presume it would be the fuse which would affect other things. the problem is audi want £200 for a new one which i could not return if it was not the pump which was defective ! does anyone know how i can find out if it is the pump or the connector etc which is defective before i part with the cash. any advice on this would be greatly appreciated. also, can anyone explain the function of this part which might give me a better idea of what the problem might be
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  3. enda1
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    enda1 Member

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    [Apr 2, 2007]
    Gaz.
    Automatics don't have the same level of engine braking as a manual due to the nature of the gearbox. This means they don't generate enough vacuum during braking as the inlet manifold is not generating enough vacuum for the servo and hence the pump makes up the difference.
    It could be one of the following.
    1) the vacuum sensor is knackered. you could try a jumper cable aross this sensor to see if brings on the relay and pump but I haven't looked at the sensor so I don't know the wiring layout.
    2)The relay to bring in the pump is knackered. Try a different relay and see if this works.
    3) There is a leak in you vacuum lines. You can test this using the following http://www.cyclegear.com/spgm.cfm?L1=2&L2=&L3=&L4=&item=PAR_DS-310207
    This mightyvac unit is also a brake bleeder and is a great tool. Connect this to your pipes and pull a vacuum and see if you have a leak.
    4)The vacuum pump is knackered. to test this you need to take the suction line to the servo off the pump and then get the pump to cycle (possibly run 12v direct to it). Put hand/finger over the end and see if you can feel vacuum. if not then the pump is at fault.
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  4. evomaster3000
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    evomaster3000 Member

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    [Apr 4, 2007]
    i'm after an electric vacuum pump, which autos were they fitted to and what years? and what do they look like/ locations

    Sorry to hi-jack the tread
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  5. enda1
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    enda1 Member

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    [Apr 5, 2007]
    I think they are fitted to all a6 autos. They are mounted on the right of the engine bay beside the power steering resevoir
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