You mean, to pressure test the system. I'll have a think, but would have no idea where to start or go.
I'm gonna try to get under the car, to check the tip, but i'm sure thats ok.
I think that hissing sound may have been the Air Con pump, as i Had a look yesterday, checked the MAP, and the I/C piping, and all seems ok, checked the I/C and all looked ok, but will see if i can get that presure tested also.
but checked all around that area, and could see nothing. Carl / Daz / Rogers, any chace you can have a good listen under the front bumper, drivers side, underneath the headlight, to see if you can hear any type of hissing, please. (Wll probably need to stick your head under the bumper.)
Will also check the DP, to make sure thats all on tight.