Paul Philpot Posted July 13, 2018 Share Posted July 13, 2018 Fitted new head gasket, water pump, leaky fan switch, thermostat, temperature sensor etc. Car runs perfectly but fan not coming on until in the red. Any ideas? Car is 1994 Supersport K series 1.4 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 13, 2018 Member Share Posted July 13, 2018 But reliably coming on when it does... except too hot?Does it come on immediately and consistently when you short the wires at the sensor?Have you got a multimeter and a wiring diagram?Jonathan Link to comment Share on other sites More sharing options...
revilla Posted July 13, 2018 Share Posted July 13, 2018 Are BOTH top and bottom radiator hoses getting hot? If the bottom hose isn't, it might suggest that you've got an airlock after filling the cooling system and the water isn't circulating properly. In this case the fan switch will be a lot cooler than the indicated water temperature and the fan won't come on. Link to comment Share on other sites More sharing options...
SM25T Posted July 13, 2018 Share Posted July 13, 2018 Did you look at the rating 'open/closed' on the old and new fan switch ... are they the same. I would agree that an airlock or low water level in radiator header may be a factor. Link to comment Share on other sites More sharing options...
Stridey Posted July 13, 2018 Share Posted July 13, 2018 It’s a tricky balance ( having taken a while to get an acceptable balance on mine).Checking the thermostat in a pan on the cooker with a thermometer diagnosed a faulty one for me.Replaced fan switch. I am a big advocate of wiring an override in as well, to anticipate traffic stops in hot weather. Also I have a light on the dash to tell me when fan is on. Bit of piece of mind. Wiring a temporary override (assuming fan works) is very simple as a get you home fix. Those tiny crocadile clipped wires can be handy.I’m now acutely aware of how outside temp can affect overall temps, I see on my regular drive where I expect fan to come on and how a good run in shaded trees can bring temp down and fan goes off. Link to comment Share on other sites More sharing options...
p.mole1 Posted July 13, 2018 Share Posted July 13, 2018 If your radiator has a the screwed fitting near the top hose remove this and if and top up the radiator till it is full. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 13, 2018 Share Posted July 13, 2018 Lots if stuff in archives about override switches, relays and clearing airlocks. Best way to clear an airlock is to raise the front of the car as high as possible on jacks (safely!) and run engine with rad cap and top plug removed until hot, keeping topped up, although it'd sometimes easier to drain down again first. Trapped air usually comes out with a burp, a bit like 'winding' a baby!Paul Link to comment Share on other sites More sharing options...
Paul Philpot Posted July 25, 2018 Author Share Posted July 25, 2018 New switch fitted and car fully 'winded' by burping... and what a burp it was!!!Thanks everybody.Paul Link to comment Share on other sites More sharing options...
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