Ok. My wife is driving car. And sitting in heavy traffic in Belfast. She calls me and tells me the temperature gauge is at full temp. I tell her to immediately turn the ar off and wait for me. I arrive and switch on ignition without starting the car and it it now shows normal 3 bars (20 mins before I arrived at scene).
Pulled bonnet and slowly removed rad cap. Turned car on and watched a few bubbles (only for about 5 secs) appear before it settled. As car heated up the water level rose and flowed over. The fan did not kick in. I turned on the AC and both fans started.
This is the first time the car has done this, it is also the first time she has been in stand still traffic (about 16C)
My initial thoughts were panic, now I've settled down a bit and am thinking a bit more methodically I have checked fan fuse which is ok. TE fact that both fans kick on with AC tells me they're ok. So surely I must be looking at a thermo switch?
Correct me if I'm wrong please. Any advice or tips or locations of said fault would be greatly appreciated.
Many Thanks

 

Thermostat could be bad or water pump.

 

not enough info. Has the radiator ever been changed. if not it is likely leaking. do you smell antifreeze at the fron of the car. If you did recently put a radiator in the car there is probably air in the system. It is not easy to make sure every bit of air gets bled out and if there is ANY air in it at all the car WILL run hot

 

hope she didnt run it to long as the heat causes head warping and / or block issues

 

No, she hasn't had a rad and i cant smell any antifreeze at all. It was run for maybe 5 mins top when overheated. I've ordered a new fan switch, thermostat and rad cap. Once these are fitted i'll be having her pressure tested. Is there a thread on both thermostat replacement and also one on bleeding the cooling system (i hear it's a bitch)