coolant leak at front of front right wheel

[semirapid]

hi could anyone help me please i have a 99 boxster iv had it about 6 month and i love it.i had a coolant leak at the right rear wheel well when i got the car and i replaced the expansion tank and it sorted it but now iv got another coolant leak from in front of the front right wheel well but it only leaks intermitantly and only when iv been out in the car and just turnned the engine off.my friend has a 98 boxster so i borrowed his expansion tank cap but im still getting the problem.if anyone has had this problem or can help i would be verry greatfull.... thanks.