1985 Mazda 626 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Servo Diaphragm Adjustment

  1. Remove air cleaner. Plug hoses of idle compensator, thermo sensor and reed valves. Warm up engine to operating temperature. All accessories should be off. DO NOT  adjust while electric fan motor is running.
  2. On models with A/C only, disconnect A/C solenoid valve-to-servo vacuum sensing tube from servo diaphragm. Apply manifold vacuum to servo diaphragm. Engine speed should increase to 1200-1400 RPM. If not, turn adjusting screw. See Fig 2 .
    Fig 1: Adjusting Servo Diaphgarm (A/C Models)
    G42077
  3. If a vehicle is equipped with A/C and power steering, follow procedures outlined in step 1) before continuing. On power steering models, disconnect power steering solenoid valve-to-servo vacuum sensing tube.
  4. Apply manifold vacuum to servo. Engine speed should increase to 800-1000 RPM on manual transaxle models and 1050-1250 RPM on automatic transaxle models.
  5. If engine speed must be adjusted, turn adjusting screw on servo diaphragm head. Recheck engine speed.
Fig 2: Adjusting Servo Diaphragm (A/C Models)
G42078
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.