As the fluid cools it creates a slight vacuum. It should pull fluid back in via the overflow.

I'm guessing the hose is so week it's easier to collapse than draw fluid back from the overflow. Replace the hoses both upper and lower. Also check to make sure there is no gunk in the bottom of your overflow preventing the reverse flow.

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98 Montero with cold weather package
96 Toyota Land Cruiser, fully locked Mall Machine :-)