Nope. Where would you like the overflow coolant to go? When everything is working normally, the coolant expands when the engine warms up, and it goes into the reservoir. Air comes out through that top hose. When the engine and coolant cool down, air comes back in through that hose to replace the coolant that went back into the engine. That hose is just there to direct any coolant or steam away from you as you're peeking at the reservoir.
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Monday, July 13th, 2015 AT 6:45 PM