Is there some way of checking if the fans start without waiting for the engine to overheat?
Also should both fans start when the temperature from the Otter switch activates?
Cooling Fans
Without going to check at my car I think this is how the otter switch is wired you should have one wire to the lug on the the top and one as an earth. Join the two together and it should start the fans. I thin k you will have to have the ignition on to do this.
Mine is a '61 with positive earth not like your 'modern' cars
but I think the principles are the same.
As for the fans I don't know for certain but my bet would be both fans should come on at the same time otherwise you would require two otter switches set at slightly different temps to get one to come on and if the heat kept increasing then the other would come on.
Hope this is of some help.
Dave
Mine is a '61 with positive earth not like your 'modern' cars
but I think the principles are the same.As for the fans I don't know for certain but my bet would be both fans should come on at the same time otherwise you would require two otter switches set at slightly different temps to get one to come on and if the heat kept increasing then the other would come on.
Hope this is of some help.
Dave
-
stuarthardy
- Posts:488
- Joined:Thu May 14, 2009 8:56 pm
- Location:North Shropshire
Dave is right, simply shorting out the Otter switch should switch on the fans.
I'm not sure whether the feed fuse is ignition controlled or not. If it isn't then the fans should run and continue to cool the car after switching the engine off. This prevents heat soak and can improve hot starting. If your car doesn't do this then it is a worthwhile modification to make because it helps to prevent heat soak, which can cause hot starting problems. You need to be aware of this when working under the bonnet in case they start up without warning - could give you a nice hair cut.
You can test the Otter switch by connecting a test lamp to it and immersing it in water ( I have an old electric kettle I use for such things) and heating it whilst monitoring the temperature (I use a thermocouple). For accurate results, stir the water as you go. The switch should have a snap action so it should be either on or off. If the bulb gets gradually brighter then the bimetal is creeping and the switch should be replaced.
Don't forget that the switch will not reset to off until the temperature has dropped well below the operating temperature.
Regards
Stuart
I'm not sure whether the feed fuse is ignition controlled or not. If it isn't then the fans should run and continue to cool the car after switching the engine off. This prevents heat soak and can improve hot starting. If your car doesn't do this then it is a worthwhile modification to make because it helps to prevent heat soak, which can cause hot starting problems. You need to be aware of this when working under the bonnet in case they start up without warning - could give you a nice hair cut.
You can test the Otter switch by connecting a test lamp to it and immersing it in water ( I have an old electric kettle I use for such things) and heating it whilst monitoring the temperature (I use a thermocouple). For accurate results, stir the water as you go. The switch should have a snap action so it should be either on or off. If the bulb gets gradually brighter then the bimetal is creeping and the switch should be replaced.
Don't forget that the switch will not reset to off until the temperature has dropped well below the operating temperature.
Regards
Stuart
Stuart
1962 E-Type FHC
1969 420 Daimler Sovereign
1994 X300 XJR
1962 E-Type FHC
1969 420 Daimler Sovereign
1994 X300 XJR
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