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Technical Question

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  • 13-06-2003 11:34am
    #1
    Borzoi
    Registered Users Posts: 2,876 ✭✭✭


    Just got the car NCT, passed no problem (whew) but I've noticed that the engine temperature gauge is only working intermitently - sometimes it does, sometimes not.

    The question is whether I need to worry, does this indicate a thermostat failure, or is it just the gauge, and a loose connection. otherwise the car is fine.

    The car is a 95 Saab 900

    thanking in advance


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    #2
    mike65
    Closed Accounts Posts: 88,978 ✭✭✭✭mike65


    Almost certainly the gauge not the thermostat, time to take the dash apart!

    If the thermostat were failing/failed the gauge would be at the max and you'd have steam under the bonnet!

    Mike.


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    #3
    BrianD3
    Registered Users Posts: 8,386 ✭✭✭BrianD3


    Sounds like a fault with the gauge alright - but it could still be a fault with the thermostat or something more serious. The thermostat could be sticking open intermittently causing the car to run too cold which could result in the gauge displaying little or no rise in termperature giving the impression that the gauge is not working. Does the car warm up ok? The heater should give out hot air after a few minutes driving from cold (even on the coldest mornings) If it doesn't you could well have a stuck open thermostat.

    Also, I believe that an airlock in the circuit could cause the gauge to give an incorrect reading. I'm not exactly sure how these gauges work - do they display the temperature of the coolant or of the engine block itself? If they measure the coolant temperature an airlock could well cause an incorrect reading. Because if the sensor for the gauge is supposed to be immersed in coolant and is in fact immersed in air it could throw things off. I know in my car the fan switch sensor is in the rad and if there's an airlock the fan may not come on when it's supposed to. Anyhow I think the airlock theory is unlikely. Still you should get the car checked out because if it overheats you could be looking at a warped cylinder head, blown HG etc. which will be big money to put right.

    BrianD3


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    #4
    Borzoi
    Registered Users Posts: 2,876 ✭✭✭Borzoi


    Thanks guys, but over the weekend while doing a bit of driving I noticed that the gauge would stay down, then suddenly leap to normal driving teperature, then sometime drop again. seem to be purely a loose connection.

    Might take out the Haynes and double check it all


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