im confused

hi there wonder if anyone can shed any light..........have a mk1 1.8gti which seems to be getting hot?ive been down a few roads to try to sovle this problem...new head gasket...new thermostat new fan switch..new hoses...checked the fan works fine and comes on about just under 3/4 way up the gauge which in turn then cools the temp to about 1/2 way up the gauge but soon as the fan stops its back upto the 3/4......thought id try wat i believe is the temp sender on the flange which comes out of the front of the head but when i put in the new one the fan dint come on until over 3/4 up the guage which has really confused me surely with the new sender in the fan should at least kick in at the same point if not sooner than my old one???might it just be a faulty gauge?????????any ideas....oh and does anyone know what the other sensor is on the oil filter head????????????

nothing on the engine controls when the fan kicks in, it is soley the fan switch on the rad, i belive there are a few different versions with different temps so may be worth checking what u have in and add one that puts the fan on sooner, or switch to a mk2 rad and fan as they have two stage fans on there this may help.

if timing is  out it can make it run hot but from what you have said about the fan/ temp  it seems to be working as it should. do you think the car drives ok ?  what rpm does it tickover at ?

How old is the radiator? Is it all gunged up if you look through it? If so run a hose through it to clear the crud. You could take it off and back flush it too as the bottom may be full of crud.

My son ran his without the grille for a while and it ran warmer!

Old water pumps can corrode ie: metal impeller blades rot and get smaller meaning it doesnt shift water at the required rate?

Are ALL the hoses replaced. Some old small bore ones can swell/balloon internally while looking ok but restricting the flow?

HTH and good luck.