chrisc11

That is excellent info thank you guys so much!  I'll measure it and then search around to see what I can find! thanks again!

Hello chaps,

Please excuse my ignorance because when it comes to cars I know absolutely nothing, I am posting this because my granddad has a Triumph Herald 1200 and always comes to me when he needs to buy parts online and I am having a hard time figuring out what half of them are even called, let alone find them on ebay for a price my granddad approves.  I took a picture and I would really appreciate it if someone could point me in the right direction.  What is this thing:

My granddad says it's a cap for the coolant system and the problem is that it's leaking so he needs a new one.

Thank you guys!