Hi,

For the second time in 8-9 months my coolant filler cap has come apart such that the yellow top comes away in your hand but the black threaded part remains in situ in the reservoir opening.

It's been over-tightened as far as I know (certainly not by me) so I'm looking for a better solution. Does anyone recommend using a one piece metal filler cap instead? Does anyone know the size of thread I would, as I'll probably end up damaging the black bit when I come to remove it.

Any ideas?