ill try rite best english i can...i just start my car and waited for it to cut out..when it did i see that a little bit of smoke was coming out of the radiator (wasnt there before it stalled)...the problems there i recken...just foned fiat glen hopkin they wanted £95 2 do a diagnostic.fink ill just take it there next week some time see whats wrong and fix it myself.dont wana just buy a new raditor and hope 4 the best.rather no what parts 2 buy 1st.
Thanks for understanding, and it's much easier to read what you you write, thus making it easier to help....
It sounds like your car is overheating. The fact that you say it seems to occur at traffic lights and when you leave it for 30 mins it will run again for a little while before the same thing happens. The 'smoke' you describe exiting from the radiator would also back this up. When you're driving the car in 3rd gear @ 4k RPM, there will be much more pressure and you may not realise how much coolant is being lost from this 'smoke'
Ok, firstly...how much coolant is in the tank when the engine is cold, and also are you losing any coolant at all?
Is the smoke coming from somewhere on the radiator itself, the bled screw or the cap? If there is 'smoke' coming from the radiator, it's more likely hot steam/water vapour. Anyway, it's not good for the engine, and over a long drive it could basically drain of the coolant and cause the car to overheat.
When you start the car and allow it to tick over, does the radiator fan come on at all? When the water gets too hot, the fan should come on and cool it down, if it does not come on, then the water can boil over, increase pressure and force itself out of the radiator cap which the cap is designed to do.
Anyway, I wouldn't suggest driving it as air getting into the coolant system could cause an airlock, or even total loss of coolant which could cause a head hasket failure and that could be very expensive to fix.
I also would not bring it to a fiat garage, they will charge you £95 to simply tell you what is wrong with it, before they even fix the problem. Go to a small, independant garage which builds itself on reputation, it will be much, much cheaper (maybe half the price, or more) than a fiat dealer.
I hope this helps.