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Coolant temp gauge problems on A4 (B6) TDI

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by sherbet31, Feb 2, 2012.

  1. sherbet31
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    sherbet31 New Member

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    [Feb 2, 2012]
    HI,

    I am hoping someone out there can give me some advise on a problem i am having with my 2003 1.9 TDI 130 A4.

    The coolant temperature showing on the gauge was only going to just above 70 degrees when i was on the motorway. I replaced the thermostat and the coolant temp sensor but there is still a problem.
    The coolant temp will now get to 90 degrees but it sems to take a while and if i stop for traffic lights or traffic the gauge starts to drop towards 70 degrees again.
    Tonight i got the temp upto 90 degrees and then left the car idling for approx 5 minutes and the temperature dropped down to 70 degrees. If i turn the car off for about 10 minutes or so the temperature again has dropped to around 70.
    Is it possible that the viscous fan could be causing this?
    I have checked the fan after 15 minutes driving and it seemed to spin freely with only a slight resistance and when the engine is cold the resistance goes.

    Please Help!!!

    Regards
    Sherbet
    #1
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  3. marktdisport
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    marktdisport Active Member

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    [Feb 2, 2012]
    it seems we all have the same issue with the B6 130hp,
    #2
  4. stu_m
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    stu_m Well-Known Member VCDS Map User

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    [Feb 2, 2012]
    Turn your heating off and see what happens

    It should warm up and hold temp

    Your heating is acting like a radiator in this cold weather
    #3
  5. quattro tony
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    quattro tony Member

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    [Feb 2, 2012]
    Ive had an erratic temp gauge with my previous a4 1.9 tdi 130, It would rarely get to 90 degrees only when going long distance on motorways, most of the time it would sit around 70, 80 ish, temp sensor had been done , slightly improved, mpg still good so just left it.
    #4
  6. stu_m
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    stu_m Well-Known Member VCDS Map User

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    [Feb 2, 2012]
    Once mine gets to 90 it will sit there all day long

    Unless I have the heating off and then turn it on when the gauge gets to 90 it will drop to 70 ish then come back up slowly in hot weather it just gets to 90 in no time at all
    #5
  7. yendall24
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    yendall24 Member

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    [Feb 2, 2012]
    i have the same engine as you and it is normal for a diesel to do this in very cold weather they are a lot more thermally eficient than petrol so therefore produce less heat .one more thing your car does not have a viscous fan you will have electric fans
    #6
  8. stuhow3361
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    stuhow3361 Member

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    [Feb 3, 2012]
    my temp gauge works occasionally but most of the time it reads zero,what needs changing and approx how much?
    #7
  9. pauldazzle
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    pauldazzle Active Member

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    [Feb 3, 2012]
    Coolant temp sensor 1st, & if that doesn't improve things change the thermostat.
    #8
  10. stuhow3361
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    stuhow3361 Member

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    [Feb 3, 2012]
    where's the sensor located on the 1.9tdi?
    #9
  11. pauldazzle
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    pauldazzle Active Member

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    [Feb 3, 2012]
    It's a bit of pain to get at as it's tucked away at the rear of the engine. I found the easiest way to get at it was to remove the large boost pipe off that runs around the rear of the engine.
    #10
  12. jay786
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    jay786 Member

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    [Feb 25, 2012]
    Same Problem .. if the heatings on it goes down to 70 Degrees .. is that normal? ... is that supposed to happen?
    How do i fix this .. air in the cooling system?
    #11
  13. pauldazzle
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    pauldazzle Active Member

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    [Feb 26, 2012]
    Sounds like a thermostat problem not a CTS fault.
    #12
  14. jay786
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    jay786 Member

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    [Feb 26, 2012]
    i just changed the thermostat today
    #13
  15. pauldazzle
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    pauldazzle Active Member

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    [Feb 26, 2012]
    You probably have an air lock.
    Take the header tank cap off, put the AC on hot, start the engine & hold the rpm's up to at least 2500 until temp gets up & hold it there for a few minutes. If you have an extra pair of hands available squeezing the top rad hose helps while doing this. Top up the header tank if needed, & leave the engine to cool down, then check coolant level again.
    #14
  16. pink.teg
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    pink.teg Member

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    [Feb 26, 2012]
    Just a quick Q
    my 1.9tdi Quattro 2003 has as a viscous fan .
    #15
  17. marktdisport
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    marktdisport Active Member

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    [Feb 26, 2012]
    correct
    #16

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