i just bought a new header tank cap which has got 1.3 printed on it the one already on it says .9 is there any difference???

My car just started leaking water wile i was driving along i poped the binnet and i could hear the water boiling in the tank did the cap cause it to boil???

 

is it leaking from the tank or from the yellow capped overflow behind the passenger headlight

 

cant see where its coming from more steam than water but its in the tank area

 

just found the main top water pipe has split al the way down lol

would the new cap be to blame ???