bd197

hello all,

2001 fiesta zetec S

my car runs great but my temp gauge has a mind of its own. for the first 10mins or so of driving its fine. climbs up to normal and stays there. then without warning it will rise up towards the red, stay there a while then come back down again. it will do this constantly but with no pattern. it might stay there all the time but if i stop, turn off the ignition and start the engine again it's at normal. i can set off and it might be ok for a day or two or it might go mad again in a few minutes.
i've noticed the radiator fan comes on aswell but if i restart that stops too.
i've replaced the temp sender on the cylinder head but it's exactly the same. there are no signs of over heating and i'm worried the fan motor will burn out soon.
so.....any ideas what it might be ?

eternally greatful.

dave.