What is NOT typically a cause for overheating in an engine due to low coolant?

A full coolant reservoir is not a cause of engine overheating due to low coolant levels because, by definition, having a full coolant reservoir indicates that there is an adequate supply of coolant in the system. Proper coolant levels are essential for effective heat transfer within the engine, and a full reservoir suggests that the system is not lacking coolant, which would lead to overheating.

In contrast, blocked radiators, rust in the cooling system, and leaking hoses do lead to issues with the cooling process. A blocked radiator prevents proper coolant flow and effective heat dissipation; rust can create obstructions and decrease heat transfer efficiency, and leaking hoses can lead to a loss of coolant, which ultimately results in overheating due to insufficient cooling. Thus, understanding the role of coolant and how these factors contribute to engine cooling helps clarify why a full coolant reservoir does not cause overheating.