What component could likely cause power steering fluid overheating?

The component that could likely cause power steering fluid overheating is a closed tester valve for too long. When a tester valve remains closed, it restricts the flow of power steering fluid within the system. This creates a buildup of pressure and can lead to excessive heat as the pump continues to work harder to force fluid through the restricted path. The increased resistance within the system leads to elevated temperatures in the power steering fluid, which can negatively impact the fluid's effectiveness and the overall steering system performance. Keeping the valve closed for an extended period can exacerbate this issue, leading to overheating and potential damage to the pump or other components in the power steering system.

In contrast, while a faulty power steering pump bearing might lead to noise or rough operation, it is not directly linked to overheating fluid. A blocked return line would cause fluid circulation issues, but the overheating is more closely associated with restrictions that create pressure buildup. Worn steering gear might lead to a loss of steering precision, but it does not necessarily contribute to overheating power steering fluid in the same way a confined or obstructed flow does.