Thought it was a bit funny why my fan was coming on alot,and car felt quite warm earlier in the day but never saw the temp guage go up so never thought anymore about it, then out later in the day and water started to hit my windscreen and then steam and then the temp guage shot up so pulled over. there is a big crack down the plastic bit of the radiator below the top pipe. Radiator looks almost new so what could have caused the heat/pressure build up? (car is a 95 wrx)

 

No the plastic end caps are prone to failure,mine did on a WRX 02 plated with only 23,000 mls on the clock.
If yours has lasted all this time, i for one would say youve done well out of it.

 

yes as common as any family in shameless. I am on my third (92wrx) Bought 2nd hand for my second (car is daily driver so needed quickly) the next was brand new and touch wood its been okay