Basically when im out in car and have been giving it some i look under bonnet and have water on header tank(spec r) and has sprayed around tht area now when i tighten up the cap on it it seems to tighten but cant force it up its as if once it tightens it just stops and thats as far as it goes my old rst`s caps when i tightened the felt different when they were tight , its hard to explain , but i think (dunno if they have a seal) the caps done do u think this is my problem ? or is this common its not overheating and fans come and do the usual job but when i have gave it sopm it seems to leak from somewhere and think its the cap , checked hoses and are fine , there braided so look fine ?

any help appreciated