What could be a reason for the bearings on a pump to be very hot?

In the context of pump operation, if the bearings are very hot, one potential reason could be over lubrication. When bearings are over lubricated, the excess grease or oil can create excessive friction instead of reducing it. This situation can lead to a condition where the lubricant does not flow properly, which can cause the bearings to overheat. Over lubrication can also create excessive pressure in the bearing housing, displacing the lubricant and preventing it from adequately cooling the bearings.

The other options, such as under lubrication, may lead to overheating as well, but the choice of over lubrication directly correlates with excessive heat generation due to improper lubrication management. Normal operating conditions would not typically manifest with hot bearings, as they should maintain a specific temperature range. Worn out seals can contribute to losses elsewhere in the system, but their primary function is to prevent leaks, rather than directly affecting bearing temperature in a way that causes heat. Thus, over lubrication stands out as a clear cause of increased bearing temperature.