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Temp guage slow to rise / not at all

Discussion in 'A3/S3 Forum (8L Chassis)' started by scott_johnson, Sep 30, 2010.

  1. scott_johnson
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    scott_johnson Audiless

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    [Sep 30, 2010]
    Hey all..

    Temp guage dosent seem to be working properly, its sort of all or nothing.

    Sometimes itll warm up to 90, although taking over 20 mins, then will drop to 0 again?

    Common fault / easy fix?
    #1
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  3. mk1chopper
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    mk1chopper Missing the S3

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    [Sep 30, 2010]
    Sounds like your thermostat has broken, not a hard or expensive job to replace. Do a search on it should return a few threads where people have replaced them. If its not the thermostat its more than likely the temp sender, also easy to replace.
    #2
  4. mulli01
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    mulli01 Member

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    [Sep 30, 2010]
    i had the same symtoms as you've described, i replaced the temp sender and now the thermostat stays at 90° or just below
    didn't take 5 mins to replace
    #3
  5. Speedy Steve
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    Speedy Steve Active Member

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    [Sep 30, 2010]
    Yeah id try the temp sender first as its a dame site easier to change than the stat
    #4
  6. Imteyaz
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    Imteyaz 6th Gear

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    [Sep 30, 2010]
    If your going to change your temp sender, make sure to do it when the engine is cold. Also, try and get a new o-ring for it too when purchasing the sender. Open the cap on the expansion tank to relieve any pressure in the coolant system and close it again. Temp sender is located at the right side of the head, held in by a black plastic 'horse-shoe' clip.

    Pull out this horse-shoe clip and lift out sender - make sure the o-ring is also removed at this stage (it tends to stay on the platic flange and you'll wonder why the new sender with its new o-ring dont fit!). By keeping the cap on the expansion tank, it creates an airlocks of sorts and stops all the coolant gushing out, this method will let it loose about a tablespoons worth. HTH,
    #5
  7. TimG
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    TimG Active Member

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    [Sep 30, 2010]
    I have the needle not reaching 90 degree problem. In traffic it hits 90, but on the move it barely makes 70, I assume as the thermostat is stuck open and the radiator is cooling the car down when moving. I changed the temp sender as its the easy first option, but it didnt sort it, and now have a thermostat to go in at the weekend! Hope it will sort it out.

    Not too sure what damage will occur by leaving it too long, I guess just some fuel economy drop as the car is 'cold' all of the time unless stationary! Not noticed a severe lack in economy though TBH.
    #6
  8. aham_uk
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    aham_uk Member VCDS Map User

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    [Oct 3, 2010]
    3-5mpg is normally the difference with a faulty sensor
    #7
  9. s3dave
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    s3dave TFSI Hybrid Supporter

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    [Oct 3, 2010]
    ^ correct you will get over -fueling of some sort they should ALWAYS stay at 90 under or over you have a problem
    #8
  10. S3KO4
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    S3KO4 Member

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    [Oct 4, 2010]
    I would put my money on the thermostat. its probably sticking open a bit. if the sender was at fault it will make no difference to the reading if the car was moving or not.
    #9
  11. HTC
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    HTC Active Member

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    [Oct 4, 2010]
    :iagree:

    Thermostat for sure.
    #10
  12. scott_johnson
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    scott_johnson Audiless

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    [Oct 4, 2010]
    Cheers guys, ordered a thermostat friday :) £23 which dosent kill the bank either :)
    #11
  13. Dazboss
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    Dazboss Like A Thristy Dingo ;)

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    [Oct 4, 2010]
    Im just about to change my stat today. Make sure you have a jiggle pin on it if not drill a small 6mm hole in it :)
    #12
  14. Dazboss
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    Dazboss Like A Thristy Dingo ;)

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    [Oct 4, 2010]
    Mine was taking a long time to warm up / show up warm. Just done the stat its not nice job. The bottom bolt is a joke, ze Germans must of been on the pop when they slapped the bolt holes in.
    #13
  15. Imteyaz
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    Imteyaz 6th Gear

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    [Oct 9, 2010]
    Stealerships charge around £16 for the new 'green' sender - there are two different shaped senders, make sure they supply the right one as I'm led to believe that the early cars had different shaped ones - not sure what year your car is but the later ones are "church window" shaped (technical term from the stealership I got mine :p.

    Clicky me: VWVortex.com - DIY: Replacing your temperature sender with the updated one (green-top)
    #14
  16. metricspaces
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    metricspaces Member

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    [Oct 9, 2010]
    Thermostat here is £8.05 Audi - Euro Car Parts UK
    #15
  17. Nilz
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    Nilz Defo worth the wait :)

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    [Oct 9, 2010]
    Scott,thats really expensve for a stat,can get them for bout a fiver mate.
    #16
  18. Welly
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    Welly VX220 SC Driver :)

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    [Oct 9, 2010]
    My money is on the stat also. If you see the needle rise to 90 in traffic when there is no airflow through the rad, then the sensor is clearly working as it is getting a reading.

    No dash activity, or erratic dash activity normally mean the CTS.
    #17

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