Over heating Focus

I have 1999 Focus 1.6, Just recently it has started over heating, when the temperature starts going up I have to Slow right down so the temp will drop to a normal temperature. I have changed the thermastat and
the radiator and it has been ok for 2 weeks, but it has started again. anyboby out there got any ideas to what else counld cause this problem? :?
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Strange one. Are you sure it is actually overheating?!
(engine temp relayed via ECU from CHT on this engine- no separate gauge transmitter) CHT are known to go bad, and there is a wiring mod too. I'd be checking this first.
Tim..
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I presume you replaced the hoses at the same time as the radiator. They can collapse on the inside and block the flow without looking bad on the outside.
Have you checked the level of coolant in your new radiator? Air bubbles can cause this.
If all this is OK then hopefully it is simply a broken fan or cooling switch. Less hopefully you have a failing head gasket.
You can test for the operation of the fan by leaving it idle on a hot day with the engine already warm and the hood (sorry, bonnet) up and see if the fan runs. A bad head gasket might (but only might) be signalled by coolant in the oil or vice-versa.
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