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Vacuum Amplifier

  1. Connect vacuum tester to White-Slate/Brown vacuum line with "Y" connector. Run engine at 1500 RPM. Vacuum should be less than 2.7 in. Hg. If vacuum is zero or more than 10 in. Hg, ensure that vacuum lines are connected correctly to throttle valve housing.
  2. Increase engine speed to 3200 RPM. Vacuum should be greater than 10 in. Hg. Decrease engine speed to below 3000 RPM. Vacuum should drop. If vacuum does not drop replace vacuum amplifier.
  3. If vacuum is not 10 in. Hg at 3200 RPM, connect vacuum tester to White-Slate/Blue vacuum line at vacuum amplifier. Increase engine speed slowly to 1500 RPM. If vacuum is less than 2.7 in. Hg, increase engine speed to 3200 RPM. If vacuum drops to 10 in. Hg, replace vacuum amplifier.
Fig 1: EGR System Diagram (190D)
G65854Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Fig 2: EGR System Diagram (420SEL & 560 Series)
G93926Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
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