I drive a 2016 Acadia with 100k miles, and while it runs perfectly, I keep smelling coolant once the engine gets hot, only from outside the car. It never overheats, smokes, or shows visible leaks, and I've only topped off coolant once. I'm guessing the water pump might be seeping, but it's hard to see. Has anyone else dealt with this, and should I be worried about long-term damage?