When you say pipe I assume that it's not a composite tank and fitting? I have repaired a plastic/composite tank on a Jeep with crazy glue. How ever you seal it, drain it down enough and then clean and dry it with something like brake cleaner or whatever. Carry extra water. If you are going to nurse it home and need to add water let it run while adding it. If it's real low let it cool down and then let it run while adding the water. Add it slowly so you dont have a surge of cold water hitting a hot engine and crack the heads or block. Yer flirting with disaster but worse things have been nursed home. If you do all that, drain the water out when you get home, not just for freezing but it will start rusting everything real bad.