Today i was driving my car home and i was stuck in traffic and i started watchin my tempature gauge rise past 220 then 225 then 235. So i just pulled off the side of the interstate shut the car off but turned on the key to let the fan keep running. I waited for about an hour for the traffic to clear up so i could haul it home w/o stopping. My fan temp switch isn't working which i already knew so i drove it all the way home with the A/C on so the fan would stay running. I know the fan was running cause i heard and saw it and when i looked under the hood and when my temp got up to 235 my coolent overflow tank was full. My question is i have a just realized i have a bad radiator cap, the rubber seal tore off, could this have caused this whole problem or could it be something else?

 

That probaly would not cause it, your thermo could not be opening and shutting properaly, or you could have a bad radiator, or a water pump

 

Yes , Get a new cap. You need pressure in the system for it to work proper.....Thats why they are there in the first place!

 

if it was the water pump you would hear the bearing shot on it and it would be lecking out the little hole thing the Cap , like Riley's35089rs+ said keeps the pressure in the system thats why its going intot the over flow tank. and if the radiator was shot you would see the anti-frezze on the ground.

your best bet it to get a new cap and then get a new t-stat.

 

Get a fan switch. Get a radiator cap.

Don't bother messing with the thermostat unless you just really want to for some reason. The other things you mention are entirely enough by themselves to account for the symptoms you are observing. This is not rocket science here.

After you fix what you already know is broken, then start looking for other stuff you don't already know about yet. You may find that it works fine.