What causes coolant to be lost through the overflow?

Coolant can be lost through the overflow due to a few reasons, primarily related to overheating. When the engine temperature rises excessively, the pressure in the cooling system increases, causing coolant to escape through the overflow reservoir. Additionally, a faulty radiator cap, which fails to maintain proper pressure, can also lead to coolant loss. Leaks in hoses or connections may further contribute to the issue.