How to Tell if an Intake Manifold Is Leaking

If an intake manifold is leaking, excess air gets into the manifold and disturbs the air-fuel ratio. The air-fuel ratio on most cars is 14 parts air to 1 part fuel. If excess air disturbs that ratio, the engine runs lean -- which means there is too much air and not enough gas. If the mixture is too lean, excess heat is created inside the engine, which causes detonation (pinging) and could eventually cause internal engine damage.

• 1

  Start the vehicle. Listen for an air leak. If the intake is leaking bad enough, you might hear the air whistling as it is sucked past the broken intake manifold gasket. If you cannot find a leaking vacuum hose, the intake manifold is suspect.

• 2

  Spray the area where the intake manifold mates with the lifter galley with the carburetor cleaner.

• 3

  Spray the carburetor cleaner in a steady stream until the vehicle's idle evens out. The carburetor cleaner blocks the air for a few seconds, thus correcting the mixture.