Hello, Thanks for the replies. The whole breather thing was where I was going with this thread. Basically the original cumbled, so I did the piece of pipe with the bolt in, and the car kept breaking down. Once the pipe wqas removed it worked fine, albeit a little bit smelly :) I have now fitted a new breather rubber on the filler cap, so that should allow it to breathe. I will do the pipe with bolt again and see if I break down. If I do, then the one way valve will be the next option. If that is the case, where would I get the one way valve from? Is that something the local motor factors would sell? Many thanks for all replies, much appreciated