[casioqv]

Don't fix it with thin walled aluminum pipe, that will be a possible corrosion issue long term. Those pipes are suitable for air only, not coolant. Since this hose goes from the IP to the head, stiffness isn't a concern so you can replace it with stiffer than stock hose or pipe.

If I were you, I would just get a brass or copper size adapter that adapts from the size on one end of the hose to the other. Then you can run regular off the shelf coolant hose from any auto parts store. You could solder this yourself from copper pipe fittings, or buy one at most industrial hose supply stores.

In the short term, you can make the hose survive until you get a replacement going by wrapping it in a layer of "hose repair tape" as sold in truck stops, then wrap diagonally in two directions with dental floss, and then wrap again with a layer of hose repair tape. I've done this on hoses before, and suspect even the worst hoses would survive months of normal use with this treatment. I never drive an old diesel anywhere without this tape and dental floss in the glove box.

Another option is to just remove the cold start device and cap off it's hoses. I don't know how well that would work in your climate, but in warmer areas I think it would be fine.