Ka overheating problem

The engine boils up, but I get no temperature warning light and the radiator fan does not run. Checked the temperature sensor and it reads about 50
kohms cold, going down to about 5 kohms in near-boiling water from a kettle - does that seem about right? I would suspect the fan motor (plug connector seems clean & OK - but can't connect to the plug pins to check continuity), except for the lack of warning light. Grateful for any ideas / suggestions.
TrevM
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I should have mentioned it's a late '02 Duratec 1.3 8V engine. Also the water is circulating through the rad, and the heater gets hot, which I think means the thermostat is OK?
TrevM.
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Does not mean the thermostat is OK. If the engine boils and the radiator is not very hot, check the thermostat. Easy way to see how hot the radiator is, just pour some water on it. If it boils, it's hot.
Al
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Thanks for the thought, but the rad gets red-hot, top to bottom, so as I said there seems to be full circulation going on. I have checked the 3(?) relevant fuses all OK, but can not find the fan relay K45 - where the f* are the relays?! There is high speed fan relay somewhere too, but normal speed would be OK for a start... Looks as if I am going to have to test the fan motor somehow: the connections look pretty hard to get at...
My first Ford had gravity water circulation - no pump, fuses, thermostat, relays, PCM... Happy days!
TrevM
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You were right, Al: it was the thermostat. The rad seemed pretty hot when I first checked, but the car had been standing a while. After another short run, the water going through the heater again got very hot but this time the rad was nearly cold. Fitted a new 'stat today - all OK now - tricky little job, though - not recommended for a beginner!
Incidentally, the thermostat & sealing ring came to over 25 at a Ford dealer: about 100 times the cost of similar items when I started out playing around with cars about 40 years ago! Over the same period, a gallon of petrol has gone up by a factor of about 20 times...
Thanks, TrevM
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