In the event of an engine overheating, where is the coolant likely to boil first?

The coolant is likely to boil first at the inlet to the coolant pump because this area is typically under lower pressure compared to other parts of the engine cooling system. When an engine overheats, the coolant's temperature can exceed its boiling point, leading to the formation of steam.

Inlet areas, especially where the coolant enters the pump, are most susceptible to reaching this boiling point first due to the dynamic nature of the cooling system. As coolant circulates, it absorbs heat from the engine components, and if the system is compromised (such as with low coolant levels or insufficient circulation), it can create hot spots. The inlet to the coolant pump may not be as effectively cooled as other areas, allowing the coolant there to boil before it reaches more temperature-stable areas like the engine water jacket or the top of the radiator tank, where coolant pressure and flow are typically more controlled.

Understanding this concept is essential for diagnosing cooling system issues and preventing engine damage due to overheating.