What are the signs of a leaking intake manifold?

Updated April 17, 2017

A leaking intake manifold can severely disrupt a vehicle engine's performance and cause a variety of abnormal engine signs and symptoms. Leaky intake manifolds prevent the adequate flow of air and fuel into a vehicle's engine and combustion chambers, a situation that has far-reaching impacts on engine performance, functionality and reliability.

Engine Miss

Many times, a vehicle with a leaking intake manifold experiences an engine miss, or an irregular engine cycle. A leaky intake manifold allows intake gases (air and fuel) to leak out into the outside air, disrupting normal engine combustion, which leads to an engine miss.

Engine Noise

A leaking intake manifold allows engine intake gases to escape during engine operation.These escaping gases, which are travelling at very high speeds, can be heard as loud hissing sounds as they leak out of a leaky intake manifold.

Engine Hesitation

By interfering with the amount of air/fuel mixture that reaches a vehicle's engine, a leaking intake manifold negatively impacts engine combustion and power. This can cause a vehicle to hesitate or stumble, especially upon acceleration from a stop.

Low Engine Power

It's common for a vehicle with a leaky intake manifold to experience reduced engine power. This is due to the amount of air/fuel mixture that escapes from the leaky section of intake manifold. The wasted air/fuel mixture gases impedes engine combustion, which in turn causes a power loss.

Hard Starting Condition

A leaky intake manifold can make a car hard to start. By allowing a large portion of the air/fuel mixture to escape rather than enter the engine, a leaky intake manifold prevents normal engine combustion from occurring, which in turn affects vehicle starting, especially a vehicle that has been sitting for long periods of time.

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