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engine temp issue? CTS or Thermostat?

Discussion in 'A3/S3 Forum (8L Chassis)' started by S3featesV9, Dec 12, 2011.

  1. S3featesV9
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    S3featesV9 Active Member

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    [Dec 12, 2011]
    hi all, ive had a good read through lots of threads about engine temp issues. and it seems the thermostat is just as common as the temp sensor.

    but i cant quite fiqure out what my issue is, so here goes...

    driving this morning, i did approx 20 miles, got home from the misses place and noticed my engine temp wasnt quite at 90. was about 86. so i decided to go back out and try and get it to 90 as ive never had this before usually up to temp within minutes. was driving like an arse at high revs and it wouldnt budge. then sat at traffic lights and it dropped to about 83 ish. then when i pulled away it rose to about the same 86-87. and thats as far as it went.

    do you reckon its the sensor? or thermostat? im going to take it for a blast to the jet wash later...see if it rises to full temp.

    im hoping it isnt the thermostat as i have read its a right pain to do, a job that involves alot of swearing and tool chucking?
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  3. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 12, 2011]
    Normally if it's the stat the temp will go down as you drive along as cold air is getting to the rad and the stat cant open enough to keep the temp up.
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 12, 2011]
    If its the stat, it will usually rise if parked and left running.

    Make sure the AC is OFF, so the cooling fans arent running, get the engine warm, then view the temp on channel 49c on the climate control unit. If its the stat then once parked it should start climbing upto and beyond 90c.

    If the stat is faulty, it usually gets cooler as you drive faster.

    On mine recently it was fine around town, getting up to 90 just fine, but get onto a motorway and sit at 70 and it would start dropping and would settle around 75c.
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  5. S3featesV9
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    S3featesV9 Active Member

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    [Dec 12, 2011]
    Channel 49c?

    Well I left car running at home for 10 mins whilst I hoovered it out and it had risen to bang on 90. Left home and drove work, it went down to about 80 and stayed there the way here. Now parked up in work car park, car running and it's rise. To 90 again. Not budging above so I'm guessing the thermostat has stuck open?? Better than being stuck closed I suppose. Or could it be something else?

    How difficult is it to actually do the thermo? As I've rear mixed views. It looks pretty easy. But things are never that simple in my life
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 12, 2011]
    Sounds like the stat to me.

    To view the actual temperature, hold down the recirc button and press the up arrow (windscreen flow) The display will change to 1c. Use the temp +/- controls to make it read 49c, then press recirc again and the display will change to show the exact coolant temp.

    You will find the guage lies, and shows 90c over a range of 80-100c or so, this is normal. With a working thermostat the reading should come up to 90 (both my A4's seem to sit at 92) and stay there +/- a degree or two when driving. If you stop they'll start creeping up until the fan kicks in around 100c.
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  7. Nilz
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    Nilz Defo worth the wait :)

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    [Dec 12, 2011]
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  8. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    Well just got home from work and did the channel 49 thing. I waited until it read 90 then set of home, soon as I hit the main road it tumbled down to about 75 and fluctuated between 74-80. Then parked up at a lay by let is rise to 90 again. Carried on and same happened. So deffo the thermostat.

    So just wondering is it worth me driving out to my local Audi dealer to get a thermostat and coolant or can I pop to Allparts just around the corner from home?

    What coolant is advised and how much will I be needing?

    Also as for draining the old stuff out which pipe should I use? And what's the safest way to fill up ensuring all air is out?

    Sorry so many questions just I have an enormous journey Wednesday morning and I'm not up for doing it whilst my mpg is utter horse sh*t. So it needs to be done today, quickly and correctly.

    Just thought, is it worth an engine and radiator flush whilst I'm at it?

    Cheers guys!
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  9. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    Anyone?
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  10. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2011]
    Defo sounds like the Thermostat mate. You can get a thermostat from any parts place but some people have had issues with them.

    Dont worry about draining any fluid. Follow the guide posted. When you remove the thermostat you need to be quick to pop the new one in but some coolant will leak out when you do it.

    You will need G12 coolant and just top up the header tank Once you've got everything back together.
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  11. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    £8 part, jeez that's cheap. How much antifreeze am I going to loose? 5ltr is about £23. Should be enough, just top up the rest with water if I'm short?
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  12. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2011]
    Mate you wont even loose half a litre if you get the new stat in place nice and quickly. It's always god to have some spare G12 on the shelf anyway.

    Dont forget to buy a brand new o-ring for the stat too.
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  13. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 13, 2011]
    i dont how how bad a job it is on the A3, the A4's pretty easy as its mounted near enough at the bottom of the engine and directly accessible from underneath.

    I've used cheap ones from the local factors at various points over the last few years and every single one has failed in short order. The replacements came from All German Parts and those have all been fine.

    If its a pig to do i'd be tempted to use a genuine Audi one.
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  14. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2011]
    It's abit tight on the S3 due to it being right next to the alternator. If the inlet mani is removed it gives you a load more space.
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  15. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    ok hmmmm. issue already.

    being me i looked for the coolant temp sensor just so i knew where it was as im replacing that too. and i decided to undo the two 10mm nuts holding it on. soon as it came off all the cooland in engine block flew out. and i shouted at myself you foooooking idiot! so ive fixed that back onto the block and changed CTS. now im about to actually do thermostat. and OMG who the hell decided to put that there! jeez! thinking about filling coolant up and leaving it lol.

    but i cant do that it needs to be done. so now i just want to make sure i am attacking the correct part
    [​IMG]

    that hose you see going to the block in middle of pic?
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  16. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    also how do i go about making sure there is coolant in the block when i fill it up? just aswell i got 5ltr of the stuff hey!!
    or will i need more now?
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  17. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2011]
    Yep that hose in your pic is the badboy. You can dilute the coolant with water you know, it doesn't have to be pure G12.

    I'm a bit confused about the temp sensor as on mine it was held in by a spring clip type of thing. Can you take a pic of what you undid?
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  18. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    [​IMG]
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  19. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2011]
    Ahh, you dont have to undo that matey.

    See the green thing on the left of your pic. That's the temp sender. It's held into the pipe by a split pin type of thing. You can just see it in your pic where the slot is in the plastic holder.

    You pull out the pin (dont drop it) then lift out the green sender and plop in the new one, then slide the pin back in to hold it in place. This will probably have an o-ring seal with it too so make sure that goes back in to seal it properly.
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  20. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    yeah i figured that out lol. i just dont know what came over me to undo is, guess i was in two minds, CTS and thermostat. and brain said 'undo the thermostat' so fingers followed my eyes haha. just wondering how do i ensure i fill the block up, as obviously atm it has...none
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  21. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2011]
    Once everything is back together just fill up the header tank with G12 up to the "Max" line. Turn on the car and let it get up to temp with the bottle cap off. This will let any air out of the system. The level will probably drop a bit as it gets around the system, just top it back up to the "Max" line and do the cap up.

    Also check the sender and stat to make sure you have no leaks.
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  22. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    Well job DONE. but im neveeeeeer doing that again. unless its sunny, warm and cars jacked up. MY BACK IS KILLING ME after leaning over for the past however long, hours i suppose.

    i got attacked by rain, i can cope with that, then the most hoooorrendous hail storm. i thought sod this is was so painfully cold lol.

    [​IMG]

    so i decided to create a shelter so i could carry on. which ment limited light, and only a poxy cheap LED torch.

    [​IMG]

    started car up and ran it to 90 checked level it hadnt dropped then soon as it hit 102 the fan kicked in and cut out at 92. checked level, had dropped a smidge. topped it up. took it for a spin left it to run on the drive for ten mins. no leaks and level all goooooood.

    p.s i dont wish this job up on anyone. it is fooking horrible. weather didnt help either
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  23. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2011]
    Well done :thumbsup:
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  24. S3featesV9
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    S3featesV9 Active Member

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    [Dec 13, 2011]
    only problem i had was that bottom bolt, couldnt quite tell if it was tight or not...time will tell.

    cheers for all the help dude
    #23

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