What is the purpose of Welch plugs installed on engines?

Welch plugs, also known as freeze plugs or core plugs, serve a specific function in the manufacturing of engines. Their primary purpose is to provide a means of removing sand that is used in the casting process of the engine block. During the casting process, sand is packed into molds to create the intricate shapes and passages required for engine components. After the casting is completed, the Welch plugs are installed to seal certain openings left for this sand removal. This ensures that the engine block is free of debris, which might affect its performance and durability.

While the other options mention important aspects of engine operation and maintenance, they do not align with the specific function of Welch plugs. For example, preventing oil leaks is typically managed through gaskets and seals, not Welch plugs. Measuring coolant temperature involves sensors and gauges that are separate from the functions of freeze plugs. Enhancing fuel mixture pertains to the air-fuel ratio adjustments in the combustion system, which is distinct from the role of Welch plugs in the engine's structure.