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Trouble with engine temperature/radiator fan

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  • [Corsa B 1993-2000] Trouble with engine temperature/radiator fan

    First, I wonder what the engine temperature normally should be on? In my case it has always been that when the temperature reaches over 100C (about 105C) the radiator fan kicks off and the temperature then drops slightly below 100C again.

    Now the fan does not work anymore (Well it starts sometimes, not always) which means that you can not run it due to overheating.

    What could be the problem?

  • #2
    Which engine do you have? Quite a few Corsa engines don't trigger the fan until the needle is nearly in the red, and I mean literally just touching it. Modern engines tend to run at around 105C.

    If you say the fan isn't starting when it should then it depends which engine you have how you check. Some older ones have a thermoswitch on the side of the radiator, if you bridge the wires on that the fan relay ought to kick in. New models use the coolant temperature sensor via the ECU to trigger the fan.

    Not knowing which model/year/engine yours is there isn't much more we can say.
    1972 Viva restoration thread -


    • #3
      Sorry, forgot to mention that.

      Opel Corsa Swing
      Engine X14SZ


      • #4
        On the X14SZ around 100 is normal.

        For the X14SZ there is a sensor that screws into the bottom of the radiator on the driver's side. Unclip the plug and bridge the connection with a paperclip. If the fan starts running then the motor is fine and it's likely you need a new sensor.

        They're only about a tenner on eBay and just unscrew from the radiator. Dead easy to change. Make sure you have something underneath to catch the coolant that will run out.
        [URL=""][B][COLOR="#0000CD"]Big clear out of parts[/COLOR][/B][/URL]
        [URL=""][B][COLOR="#0000cd"]Corsa D Yellow LE[/COLOR][/B][/URL]
        [URL=""][B][COLOR="#0000cd"]Corsa B Atlantis Blue[/COLOR][/B][/URL]
        [URL=""][B][COLOR="#006400"]Mazda Eunos V-Spec[/COLOR][/B][/URL]


        • #5
          You can also run a wire across the thermoswitch to a manual switch on the dashboard which allows you to retain the automatic operation of the fan but also enable manual override if you see the gauge going higher than you are happy with. Twin core 5amp wire is fine, the load goes via the relay, not the switch.
          1972 Viva restoration thread -


          • #6
            Which sensor exactly will I need to change? Can you link it here? Would be appreciated.
            Also Im not sure what you meant, or how I will do the "Unclip the plug and bridge the connection with a paperclip." Is this necessary?


            • #7
              It's very very straight forward. It's necessary to identify if the sensor's dud or the motor to the fan is dud.

              Basically there is a plug that connects to the sensor. Just unplug it and bridge it with a paperclip and the fan should turn on.

              This should be the sensor:

              Vauxhall Corsa Tigra Nov Radiator Thermostat Fan Switch | eBay
              [URL=""][B][COLOR="#0000CD"]Big clear out of parts[/COLOR][/B][/URL]
              [URL=""][B][COLOR="#0000cd"]Corsa D Yellow LE[/COLOR][/B][/URL]
              [URL=""][B][COLOR="#0000cd"]Corsa B Atlantis Blue[/COLOR][/B][/URL]
              [URL=""][B][COLOR="#006400"]Mazda Eunos V-Spec[/COLOR][/B][/URL]


              • #8
                OK I'm guessing you don't work on cars a lot, so as Nibnob days, it's really quite simple, nothing to worry about.

                First of all look down the side of the radiator (driver's side) and down near the lower end you'll find an electrical connection. That's the thermoswitch. When the coolant reaches a specified temperature it closes and makes a circuit. That circuit then triggers the fan relay, which connect power to the fan and turns it on. (The thermoswitch doesn't carry the power to run the fan as that would burn it out, so it's like a switch that operates another switch.)

                So, if you remove that electrical connector and bridge it (ie join its two wires together) then the relay should be activated and the fan should run. You just need the ignition on to make it work.

                (9 times out of 10 this works, which proves that the relay and the fan motor are fine. It's usually the thermoswitch that fails.)

                By putting a paperclip across the terminals in the connector you are duplicating what happens when the thermoswitch closes.

                One word of warning. If you do need to replace the thermoswitch bear in mind that it is held in place by a nut moulded into the plastic side on the radiator. Sometimes the screw threads of the switch corrode into the nut and when you try to unscrew it it rips the nut loose - in which case a new radiator is the only fix. So go careful with it.

                If you say where you are there may be someone close by who can test it for you if you aren't sure.
                1972 Viva restoration thread -


                • #9
                  Thank you.
                  Yes, you are right, I have just started to work with cars a bit
                  I will buy that sensor and will try to fix this.
                  By the way, is there a chance of getting a shock when I bridge the connection with a paperclip?

                  I doubt that anyone is close by. I live in Sweden


                  • #10
                    Turn the ignition off before you bridge the sensor connector, and make sure the paperclip isn't touching an earth when you turn it on to check the fan operation. That way you can't do any harm.

                    Sweden is a bit off my usual route.
                    1972 Viva restoration thread -


                    • #11
                      So, I did buy that sensor before looking on my current sensor.
                      And these two doesnt look identical to each other, which means the cables does not fit on the new sensor.

                      The one I bought looks like thisClick image for larger version

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                      And the currently installed looks like this Click image for larger version

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                      As you can see, they have different connections.

                      Did I buy the wrong sensor?


                      • #12
                        Is this the one I should have bought?

                        Temperature Switch Radiator Fan Opel 50190 by Standard | eBay


                        • #13
                          Well if it's not te same, then it's wrong.

                          If you've got as far as taking a pic of it, and removing old wires then why not just bridge it to see if it's the issue?


                          • #14
                            I did bridge it with paperclips. The fan started to run when I turned the ignition.


                            • #15
                              Then the fan and relay are fine. As I said early on, on many of these the fan doesn't run until the gauge is nearly in the red anyway. So if you fan is coming on at that stage you don't have a problem.

                              If you're worried fit an override switch. Only replace the sensor if the gauge hits the red and the fan doesn't cut in - because the old sensor often corrodes into the retaining nut which is held in place by a plastic moulding. It is very common for that be destroyed by trying to remove the old sensor, hence you don't do it unless you really have to.
                              1972 Viva restoration thread -