) is that any old/brittle hoses will I think be "sucked in" (I don't know to what degree, not having used this method) & will hopefully show up as an immediate failure to maintain a vacuum, but I suspect some will just be weakened & will maybe shorten the (inevitable?) timespan to failure. Either way, check ALL 17 hoses & ALL the metal pipework for potential weaknesses & replace. Personally I tend to try to go for preventative maintenance rather bthan reactive maintenance, but that is not always viable.
As Lorna says, good thorough flushing, start from scratch, then you know what's in there, coolant doesn't last forever, it degrades & it's not just antifreeze, it's anti corrosive.