MGB Register Forum

Ian, there is an air passage, but I don't know how it works. I think the cap is made in two parts and the air escapes laterally between the parts. I held a rubber tube firmly against the internal central hole and blew and the air definitely escaped from the cap.

Thanks Mike, that's interesting and also reassures me a little! Good that you got it sorted out.

Ian F

Ian,
On my caps the flat top of the cap can be pulled off & there is a small breather hole through the centre of the base. On the edge of the rim there is a tiny u shaped hole which , when the flat top is replaced enables venting. (My hand book refers to checking that these don't become blocked). These are difficult to see if you aren't aware of them.
Cheers
Charles

Thanks Charles, I definitely need my specs for that!
Good to know, always something new to learn,

Ian F