What should be checked if an engine is running hotter than normal?

When an engine is running hotter than normal, one of the primary factors to check is the coolant level. The cooling system is responsible for dissipating heat from the engine, and insufficient coolant can lead to overheating. If the coolant level is low, it can’t effectively absorb heat from the engine, causing the temperature to rise.

In addition to checking the coolant level, it's also important to consider the condition of the coolant itself, as degraded or old coolant can lose its effectiveness in regulating temperature. Inspecting hoses and the radiator for any leaks or blockages is also crucial, but the direct action of ensuring that there is enough coolant in the system is an immediate step to address overheating issues.

Other factors like oil viscosity, air filter cleanliness, and fuel quality can indirectly affect engine temperature, but they are not the primary concerns when immediate overheating occurs. For instance, oil viscosity affects lubrication at operating temperatures but does not directly influence coolant and heat management in real-time. Similarly, while having a clean air filter and good fuel quality contributes to overall engine performance, they do not play as crucial a role in managing engine heat as the coolant system does.