Thanks for checking gambit, I would leave it but I have to get it sorted as the mpg has droped by 10mpg!!!!
Got in the post this morning a used valve from a fellow kind gti member

I have given it a blow (no comments please) and the valve seems to pop nice, my original one didnto seem to do this but gurgled a bit, so hopwfully i swap em over and it will be fine

I'll check haynes out and test it, i did know about this but was not sure what setting my multimeter should be on.
Thanks again mate, i'll let you know, it's been a looooong problem
