An engine vacuum leak is a common vehicle problem that can produce a variety of mechanical and operational symptoms. By negatively impacting the natural engine vacuum pressure, a vacuum leak can seriously impede a car's performance. What follows is a brief list of the most common symptoms of a vacuum leak in a car.
Rough Engine Idle
The classic sign of a car with an engine vacuum leak is a rough engine idle. A vacuum leak causes a disruption of the normal vacuum that is created from a running engine. A vacuum leak alters the vacuum pressure of an engine, which results in a rough engine idle.
Along with a rough engine idle, engine hesitation during acceleration is one of the most common symptoms of an engine vacuum leak. During acceleration, the leaking engine vacuum pressure is more pronounced, which presents itself as a stumbling, or hesitating, engine.
Imprecise Transmission Shifting
Engine vacuum provides a large part of a transmission's operational power, a power that helps to properly shift the transmission gears. An engine vacuum leak can cause weak or imprecise transmission shifting points.
A vehicle with a vacuum leak will often have poor acceleration and reduced engine power. This is due to the escaping engine vacuum that reduces the overall force and pressure produced by the engine during combustion.
Hard Vehicle Starting
Depending on the size and location of a vehicle's vacuum leak, hard vehicle starting is often a symptom of a vacuum leak. By reducing the optimal pressure and vacuum within an operating engine, a vacuum leak can inhibit the action and function of a car's carburettor and/or fuel injection system, which directly impacts vehicle starting.