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Thermostat, cts question.

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  • [Non Corsa] Thermostat, cts question.

    Hi all

    More a question to clear up my rattled brain.


    vectra c
    1.8 16v
    54 plate
    122 bhp

    As some of you know I had to change my thermostat and housing which included a new cts too.

    After going out for a run in it today I noticed the following.

    Choke turns off as it should
    Heaters work perfectly nice hot air and cold when setting is changed to cold.
    Fan kicks in around 95c as it should
    Everything works as it should do including the temperate gauge.

    However the faster I go 40mph - 70mph the temperature gauge drops to 65 - 70c so my question is faulty thermostat?

    My self and nibnob as posted in my project believe that is the issue, but wouldn't the heaters be effected too?


  • #2
    It depends on what the gauge is reading. The Veccie has a very efficient cooling system so even in heavy traffic they don't tend to overheat. So long as the engine warms up quickly then the 'stat is doing its job. At speed (especially in the winter) the flow of cold air through the rad can cool the coolant sensed by the CTS (which drives the gauge) whilst not actually affecting the running temperature of the coolant flowing round the engine.

    As I recall the gauge doesn't actually read low temperatures that accurately, so it's just indicating that at speed the 'stat is fully open, but the cold air through the rad is dropping the coolant temp sufficient for the gauge to dip slightly. Also, if the gauge is showing 95 when the fan kicks in then the gauge itself is reading a bit low, they usually activate about 102 iirc. So don't take the gauge as absolutely accurate.

    I'd suggest it's absolutely fine - so just drive and enjoy.
    1972 Viva restoration thread -


    • #3
      Thank you very much Taurus

      Its the only car I have had that's done this so was rattled trying to work it out. And like you say the digital gauge I used in the corsa read around 103 as the fan kicked in but was 96c on the standard gauge.

      Again thank you very much
      Last edited by tanktop; 16-01-2014, 08:56 PM.