You can take a 3' long x 1/16" stainless steel bare welding rod, wrap it around 1 1/2" PVC tube and make your own inner radiator hose spring to keep it from collapsing from the suction of the water pump.
I used 2 sticks of ER70S-2 stainless rod 3 foot long. Tightly wrapped around a 1 inch PEX pipe. When released it springs out to 1.5 inch. Bend the ends in so they don't gouge the hose.
If the SS rods have the specification callout flags on the ends, snap them off as it will snap off later if you do not.
Some soapy water and some long pliers, just spin the wire in from both ends.
