NOTE: You will need a source of vacuum such as a vacuum pump
and a vacuum gauge to make these tests. You may be able to disconnect and plug
the hoses leading to this valve, then operate the engine to produce vacuum for
testing. In this case, you can tee a vacuum gauge into the line which will apply
vacuum. You will also need about four feet of vacuum line, the diameter of that
used to connect this valve into the system.
- Remove the vacuum delay valve. Cut a vacuum hose of the size used to connect
this valve into the system to 40 in. (1 meter) in length. Connect the hose
to the inlet end of this valve (the arrow on the valve should point away from
the hose connection), then attach a source of vacuum and the vacuum gauge
to the other end of the hose.
- Hold your thumb tightly against the open end of the valve. Apply a vacuum
of over 20 in. Hg (508mm Hg). Then, seal off the source of vacuum. Release
your thumb and watch the gauge as vacuum decreases to 4 in. Hg (102mm Hg).
This should take 1.3–2.3 seconds. If the time elapsed during the pressure
drop is outside this range, replace the valve.
