I have a ford fiesta 2006 1.6 Auto ambiente (ford with the pimple on the lights) i have been on many forums and still cannot understand the reasoning behind my Ford overheating. i had lost the original cap but having this problem even when i had the original water bottle cap. the car overheats up to 120 degrees , when i drive a bit faster it goes back down. i am not losing water, but water is boiling very hot inside the bottle, that i cant even open the cap, its too hot to even touch. today im going to ford to purchase the original cap, but how will this stop the car from overheating. i drove today with 120 degrees and it refused to come down, the bottle is smoking and i can see the water boiling inside. i have checked the radiator and pipes for leaks, and i checked the switch on the radiator, and the fan is working it is on but still overheating.

Water?

Ain't you supposed to use a radiator coolant? They have a higher boiling temp I think????

Isn't there a pump/belt that circulates the 'solution' in the radiator? Could this be broken?

Not sure how changing the cap will solve your issue or what I've wrote will help you?

Hope it's an easy fix.

 

The cap holds a certain amount of pressure, it's this pressure that raises the boiling point of the coolant.  If there isn't enough pressure (dodgy cap) it'll boil. 

However I'm not sure that's the problem in this case.  And I definitely wouldn't have been driving it far at 120c, likely to cook the head at temps like that!  Are you totally sure you're not losing water anywhere?  Specifically around the cap?  The coolant reservoirs on these are terrible and always cracking which gives the symptoms you describe.

Alan, I would assume he means coolant when he says water, but it doesn't alter the boiling point much if at all, it's more for anti-corrosion and not freezing in the cold.

Ofcourse liquid under pressure boils at a hight temp. Reason water boils on mount everest at a 71'C as the pressures lower.

 

I'll sit in the corner, quietly now.😦

Are you sure that the water is circulating around the system eg is the radiator and top rad hose hot etc? The pressure cap will bring the boiling point up, but even with no cap at normal air pressure it shouldn't be boiling.

When the cambelt was done was the water pump changed out as well?