Equus 3660 - Hand Vacuum Pump & Brake Bleeding Kit - Manual (Page 15)

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D. TESTING THE EGR VALVE DIAPHRAGM
1. Turn the engine "off"
2. Disconnect the vacuum hose at the EGR valve.
3. Connect the vacuum pump to the EGR valve (use the clear hose
and adapter included in the accessory kit, as necessary).
4. Squeeze and release the pump handle until 10 ~ 12 in. (26 ~ 30 cm)
Hg of vacuum is indicated on the gauge. Observe the vacuum
gauge for one minute minimum.
• Verify the vacuum gauge reading of 10 ~ 12 in. (26 ~ 30 cm)
Hg remains steady for at least one minute. If the vacuum
drops, the diaphragm is defective.
E. CHECKING EGR VALVE SEAT/RESTRICTIONS IN EXHAUST
TUBE
The only way to accurately check the EGR valve seat for contamination
or damage and the exhaust tube for restrictions is to remove the EGR
valve. Consult the manufacturer's service manual for procedures.
The EGR valve may also operate properly with the engine at normal
operating temperature, but remain open when the engine is cold. This
usually occurs when a faulty thermal switching device fails to shut off
the vacuum supply when the engine is cold.
IX. DIAGNOSING MECHANICAL ENGINE CONDITIONS
When used properly, a vacuum gauge can provide a considerable
amount of information about the internal condition of an engine.
However, it is easy to misinterpret the readings of the instrument and
thereby reach false conclusions. When using a vacuum gauge on an
engine, it is far more important to note the action and the general
location of the needle rather than the actual vacuum reading.
NOTE: Vacuum leaks or improper operation of any of the external
vacuum-operated devices (EGR valve, vacuum-operated solenoids, EVAP
system, vacuum valves, etc.) and hoses may interfere with proper engine
diagnosis by giving a false indication of current engine condition. Always
perform a preliminary check for proper operation and sealing integrity of
these devices before an engine vacuum test is performed.
1. Start and run the engine until it reaches operating temperature.
2. Connect the vacuum gauge to the intake manifold. Whenever
possible, connect the gauge hose directly to a vacuum port on the
intake manifold in order to avoid any leaks that might exist in
other connections.
3. Evaluate the test results.