If the proper hardware is used at both ends of the water jacket, there should be no need to solder the tubing. The small self-crimping nut that is a one-time use item, and the corresponding female-threaded bushing it threads into will seal the tube sufficiently without any solder. All it has to seal is cooling system pressure- - - -7 PSI at most, and zero in some older cooling systems.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!