What effect does a vacuum leak have on a diesel engine?

A vacuum leak in a diesel engine disrupts the air-fuel mixture entering the combustion chamber, which can lead to an improper ratio of air to fuel. This imbalance can cause the engine to run less smoothly, leading to rough engine performance. In essence, the engine struggles to maintain proper operation because it is not receiving the correct amount of fuel or air essential for efficient combustion. This can result in symptoms such as irregular idling, stalling, or decreased acceleration.

The other effects listed do not accurately reflect the implications of a vacuum leak. For instance, while fuel efficiency typically suffers due to an incorrect air-fuel mixture, horsepower may also be negatively impacted because the engine cannot perform at its optimal level. Similarly, a vacuum leak does not reduce wear on engine parts; instead, it can potentially lead to increased wear due to poor combustion and erratic engine behavior.