Vacuum Test

1. Connect a vacuum tester with Y distributor to vacuum amplifier line (line with check valve) and check vacuum with engine idling.
a. With an engine speed of 750 RPM, vacuum reading should be;
Manual trans 300 ± 20 mbar
Automatic trans 350 ± 20 mbar
b. Turn ignition switch to OFF position.
c. Regulating linkage should be resting against its full load stop and zero inches of vacuum should be noted.
d. If not, check vacuum line routing, vacuum pump and vacuum control valve, repair or replace components as necessary.

2. Pull vacuum line off from the vacuum control valve, and connect a vacuum gauge.
a. Vacuum at idle speed should read 360 - 410 mbar.
b. Stop engine and move the throttle linkage to its full throttle stop. Vacuum reading should go to 0.
c. If not, check for proper vacuum line routing.
d. Check supply vacuum (above 700 mbar), and vacuum vent line for restrictions.
e. Adjust vacuum control valve (step 3).
f. Replace vacuum control valve if necessary.

3. Connect vacuum tester with Y distributor onto switch-over valve top side nipple and check vacuum with engine operating at 1200 RPM and 12 volts applied.
a. On switch-over valve 125, vacuum readings should be:
Manual trans300 ± 20 mbar
Automatic trans350 ± 20 mbar
b. On switch-over valve 126, approx. 700 mbar (20 in. Hg) of vacuum should be obtained.
c. If vacuum obtained is correct, switch-over valve is satisfactory.
d. If vacuum obtained is incorrect, check vacuum pump and replace switch-over valve if necessary.