Had a search but can't find it . There is a small hose from the expansion tank down to the metal hoses. Held with a clip at each end . I know it's a known weak spot and mine does have a large split in it . Not leaking yet surprisingly, although I am out later today so it's bound to . It's about 6 inches long total.
I have read it's not a part to buy individually, but others must have a solution. It may be different size at each end , I think I have read?

Any experience and solutions welcome, thank you.
2007 XK

 

A tighter clamp on the bottom with a hose that fits best you can find? Small diameter lines carry little actual pressure since such a small area.

 

Dealer says you can't buy the rubber hose alone, you have to buy the entire assembly of metal piping. Thats nutz - I just fabricated my own hose. Make sure that the spigot from the tank isn't the culprit - that's a weak point and the fluid runs downward, maybe looking like that the hose is the culprit.
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It's not actually leaking right now , but it has a split in in , see first pic.
I will experiment with some hoses over the next few days , perhaps one hose of the spigot size with a smaller hose pushed in for the lower connection. Made up with a metal sleeve for the join. Easy access but a short run for a fiddly hose .
It must be a common fail now , but there does not seem to be anything already made up,available here in the UK.

 

What is the OD of the metal portion of the hose that has the crease in it? Can you find a rubber hose which you could slip over it, like a cuff, at least temporarily?