Overheating and hissing noise!

Hi All!

Info: Y Reg (2001) Fiesta MK5, 1.25 Zetec

So on my drive home today (15 mi. or so) I noticed that the car felt particularly warm inside even though the radiator fans were off and the dial on cold.

I then noticed that even though I had been driving for ten minutes or so the temperature gauge was barely over the cold mark :frown: The car continued to get hotter, even though the engine temp was supposedly cold.

Once the engine had cooled off I checked the coolant tank, which was an inch or two below the Minimum marks, so I topped it up with water and took it for a 5 minute round the block drive.

When I opened the bonnet afterwards there was a hissing sound coming from near the coolant tank and everything around there felt warm.

I have no idea what to check or how, and given the age of the car, any expensive fix would probably write her off :(

Any ideas? Is this an expensive issue? What should I expect from a mechanic?

And most importantly if I am checking and topping up the water is it safe to drive?!

Cheers,

Anil