Here are some reasons why you might want to change the freshwater pump on your Cummins engine:

1.     Wear and tear: Over time, the impeller and bearings of the freshwater pump can wear down due to continuous use, leading to decreased pump performance and efficiency. Eventually, the pump may stop working altogether, which can cause engine overheating and other problems.

2.     Leakage: The freshwater pump can develop leaks, which can cause loss of coolant and engine overheating. A damaged or worn-out pump can also cause leaks, which can be identified by a pool of coolant under the pump or a low coolant level.

3.     Corrosion: The freshwater pump can become corroded due to the presence of contaminants in the coolant or exposure to other corrosive agents. Corrosion can cause leaks, reduced pump performance, and eventually, pump failure.

4.     Blockage: The freshwater pump can become clogged with debris, rust, or other foreign objects, leading to reduced water flow and pump performance. If not addressed, the blockage can cause the pump to fail or the engine to overheat.

5.     Maintenance: Regular maintenance of the freshwater pump can help identify issues before they become major problems. If the pump is found to be in poor condition during routine maintenance, it may be necessary to replace it to prevent engine damage.

In summary, freshwater pumps are critical components of the engine cooling system, and they need to be in good working order to prevent engine damage and overheating. Regular maintenance and timely repairs can help prevent issues that may require pump replacement.