Servo & Vacuum Check

To determine condition of diaphragm, remove hose from servo unit and apply 15" of vacuum to tube opening and hold in for one minute. Vacuum should not leak down more than 5" in one minute. If leakage is excessive, replace servo. To utilize engine as vacuum source, proceed as follows: Disconnect servo cable or bead chain and hose from servo unit, then connect engine vacuum directly to servo fitting. Note position of servo diaphragm and start engine. Diaphragm should pull in. Clamp off engine vacuum supply line and check unit for leakage.