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Guide to changing temp sensor

Discussion in 'A3/S3 Forum (8L Chassis)' started by barters3, Nov 15, 2009.

  1. barters3
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    barters3 Member

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    [Nov 15, 2009]
    I have been searching for infomation regarding the replacement of the thermostat and temp sensor.
    I have found a guide on the thermostat, however, i am a little unsure of how much coolant i will loose when carrying out the change?

    Also where is the coolant temp sensor located? and how is it replaced?
    I would be gratefull if anyone can help.
    #1
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  3. steviet
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    steviet Member

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    [Nov 15, 2009]
    You shouldnt lose any fluid mate maybe a very tin amount.Make sure you do it with the engine cold 1st and open the res cap 1st to let the pressure out then put cap back on.
    Im not sure with the S3 where it is,but im sure it maybe where the A3 1.8T is,its on the right hand side of the rocker cover.ill try get a pic up dude
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  4. zeeeebo
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    zeeeebo Lifes one big laugh

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    [Nov 15, 2009]
    can you uploads a pic of the a3 as i need to know to but cant seem to find any info on it!
    #3
  5. steviet
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    steviet Member

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    [Nov 15, 2009]
    Soory its not the best pic,its just under where i have put the arrow!.


    [​IMG]
    #4
  6. barters3
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    barters3 Member

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    [Nov 15, 2009]
    i cant see the pic very well because im on my phone.il take a proper look later. Il order the bits and let you know how i get on. Thanks.
    #5
  7. jonny87
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    jonny87 Active Member

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    [Nov 15, 2009]
    dude, i changed these two things on my 2000 reg s3 a few weeks ago, the thermostat i drained my system (was doing a coolant change/flush too) i would say it would be worth doing at the same time, but its up to you, you will lose some coolant doing the thermostat, but not all only whats in the header and pipes above thermo!

    the temp sensor is located on the rhs of the engine, follow the top hose from your rad also on the rhs, it will lead to the back of the engine there on that hose you will find the sensor it may be black or green depending if its been changed before or not!
    its held in place by a plastic push clip, be careful not to break it as i did!! simply slid this clip out unplug the sensor and pull him out, then same but in reverse for re-fitting, job done!

    if no one has put up a decent pic by the time i get home tomorrow mate, il get one up for you ;)
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  8. Imteyaz
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    Imteyaz 6th Gear

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    [Nov 16, 2009]
    As Steviet posted earlier, if you remove the expansion tank cap to relieve any pressure in the system and then put the cap back on, you shouldn't lose much coolant when you unplug and remove the sender, I lost a couple of table spoons worth but nothing more. Make sure you change the black o-ring seal for the sender
    too, I tried in vain to get the new sender / o-ring in and then realised that the old on was still in the housing.
    #7
  9. jq_quint
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    jq_quint Member

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    [Nov 16, 2009]
    i'll second that, made a similar mistake on my 2.8 A6, tried for ages to push the sensor down low enough to slide the clip back in only to realise an old o-ring was still in the bottom. doh.. Try and clean sendor pot as much as possible also before re-inserting new sensor...
    #8
  10. jonny87
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    jonny87 Active Member

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    [Nov 16, 2009]
    heres the pics mate:
    [​IMG]
    [​IMG]

    hope this helps ya dude!!
    #9
  11. 1animal1
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    1animal1 The Clar!! it mouves!!! VCDS Map User

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    [Nov 16, 2009]
    simple to change....a 4 yr old could do it if he could reach :)
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  12. barters3
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    barters3 Member

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    [Nov 16, 2009]
    Cheers guys, il get the parts orderd and attack it at the weekend. Does the thermostat come with a replacement o ring or wil i need to order it separetly?
    #11
  13. S3 Nattie
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    S3 Nattie Quattro ist für sissies

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    [Nov 16, 2009]
    I changed mine 2 weeks ago. Yes the o ring is separate but all together for the stat it cost £11 something from GSF.

    Quick tip, you do not need to take out the 2 screws that hold that plate thing at the front of the engine. These screws usually get messed up and some people drill them. Their is 2 allen key bolts (5mm) that holds the plate to the manifold, just remove these and the plate comes off.

    I would change the stat only, see how the temp. I bought both ( sensor - £18 from GSF ) and didnt need the sensor so took it back.
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  14. jonny87
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    jonny87 Active Member

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    [Nov 17, 2009]
    mine was the other way round, replaced the thermo but the senda was the one at fault, i would advise changing the senda first, about a million times easier to do than the thermo

    also i bought both mine from motor factors (dont know what area you're from) but cost £5 for thermo with o ring and £8 for senda

    good luck dude
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