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Thermostat not opening but not overheating?

stuiwhite Sep 7, 2012

  1. stuiwhite

    stuiwhite Member

    Good morning!

    My Car: 2005 A4 B7 19 TDI SE (115bhp)

    Please understand that I have looked at every Thermostat thread available on the internet (Well that's how it feels)

    I changed my Thermostat Tuesday evening after months of having my temp gauge never going past 70,

    Took car out after and the gauge got to 90 and stayed there which is fantastic!

    I am a very nervous guy when it comes to cooling (Having needed to change 2 thermostats in the past on a MK3 Ibiza Cupra after they malfunctioned)

    I get in the car and drive to get the temp up to 90 and it nevers go's over 90 or drops anymore and my heating is working better than before (Obviously with it allowing the engine to heat up properly now!)

    However i get out every time now and check coolant levels which are always fine and feel cooling pipes to ensure things are working.

    Heres what i find:

    Top coolant pipe (Nearest to touch when looking under bonnet = Very warm/hot
    Reservoir and pipes coming from it = Warm/hot
    Radiator = Warm/hot

    Now my concern...
    Pipe coming from Thermostat housing = Cold?

    Now should i be concerned as if the car was overheating i would get a error right?

    Is this just because my car isnt getting hot enough for thermo to open?

    Do the diesels run a lot cooler and there for the thermo stays shut a lot longer?

    Any advice would be GREATLY appreciated!


  2. A4_MaJiK

    A4_MaJiK Azeem

    I can confirm first of all that diesel do run alot cooler than petrol engines. If its not going over 90 then personally I wouldn't worry about it the slightest. Coolant temperature is also dependant on driving style too. It'll only ever get so hot in traffic for instance as opposed to driving at speed with air flow coming through the radiator.
  3. stuiwhite

    stuiwhite Member

    Thank you, Really appreciate it.

    I guess im being over cautious!

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