1979 BMW 633CSi Automatic TransFACTORY OEM SERVICE PROCEDURE

Check Valve

This valve has a one-way diaphragm which prevents hot exhaust gases from backing up into the hoses and air pump. This protects the air injection system in case of pump belt failure, high exhaust system back-pressure, or air hose ruptures.

Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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

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