Equus 3660 - Hand Vacuum Pump & Brake Bleeding Kit - Manual (Page 10)

8 3660
B. VACUUM MOTOR/ACTUATOR TESTING PROCEDURES
The following procedure shows how the vacuum pump might be used to
check a vacuum motor/actuator for a leaking diaphragm:
1. Connect the vacuum pump's vacuum hose to the vacuum port of
the motor/actuator.
2. Operate the handle to apply 8-10 inches (20-25 cm) Hg of vacuum
to the motor/actuator, as shown on the vacuum gauge.
NOTE: Consult the vehicle’s service manual for specifications.
3. Observe the vacuum gauge for approximately one minute.
• If the vacuum gauge reading remains steady for one minute,
the diaphragm is not leaking.
• If the vacuum gauge reading falls, a leaking diaphragm is
indicated.
VII. TESTING THE PCV SYSTEM
A. SYSTEM DESCRIPTION AND OPERATION
The Positive Crankcase Ventilation (PCV) system helps reduce air
pollution by aiding in the scavenging and burning of harmful engine
crankcase vapors and gases before they can enter the atmosphere. The
PCV system consists essentially of an intake filter, PCV valve and
interconnecting hoses (see Figure 4).
Fresh air is drawn through the intake filter (located in the air cleaner),
through the valve cover, and into the crankcase to be mixed with the
crankcase gases. From the crankcase the gases are drawn to the
opposite valve cover, through the PCV valve, and into the intake
manifold. The intake manifold vacuum draws these crankcase gases
where they are mixed with incoming intake air to be burned during
engine combustion.
Airflow through the PCV system adds to the airflow through the
carburetor or throttle body during engine operation. During cruising
and light acceleration, intake manifold vacuum and the pressure inside
the crankcase are relatively high. The strong manifold vacuum draws
the PCV valve plunger into the narrow end of the valve, restricting
most of the flow of gases into the intake manifold. During hard
acceleration or high speed operation (heavy load condition), low intake
manifold vacuum allows the PCV valve spring to overcome the high
crankcase pressure, pushing the plunger out of the narrow end of the
PCV valve and increasing the flow of crankcase gases into the engine
for combustion.