Intake Manifold: Testing and Inspection

NOTE: An intake manifold leak is characterized by lower than normal manifold vacuum. Also one or more cylinders may not be functioning.

WARNING: USE EXTREME CAUTION WHEN THE ENGINE IS OPERATING. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR THE FAN. DO NOT WEAR LOOSE CLOTHING.

CHECKING FOR VACUUM LEAKS
1. Start the engine allowing it to warm up.
2. Inspect for disconnected vacuum hoses or hardened or cracked vacuum lines.
3. With a spray bottle, spray a small stream of water on the suspect area.
4. If there is a change in RPM'S, the suspected leak has been found.
5. Repair as required.

CLEANING
^ Clean manifold in solvent and blow dry with compressed air.
^ Clean cylinder block front and rear gasket surfaces using a suitable solvent.
^ The plenum pan rail must be clean and dry (free of all foreign material).

INSPECTION
^ Inspect manifold for cracks.
^ Inspect mating surfaces of manifold for flatness with a straightedge.