BMW Coupes and Sedans 1970-1988 Repair Guide

Automatic Air Intake Preheating Valve



See Figure 1

The automatic air induction pre-heat valve is located in a housing to the right of the radiator, on vehicles so equipped. Every 8000 miles (13,000 km), the lever should be placed in the winter (W) position and the valve's freedom of movement checked. If necessary, oil the valve. In the "W" position air drawn in at the front of the car is mixed with air preheated around the exhaust manifold in a ratio dependent on outside and engine temperatures, until it reaches approximately 86°F (30°C). At approximately this same outside temperature, the pre-heat supply hose is completely closed and the car obtains all its induction air supply from the fresh air hose. In summer, the lever should be used to set the valve to the "S" position. The cover plate can be removed for inspection purposes.

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Fig. Fig. 1: Slide out the air intake preheating assembly


See Figure 1

  1. Remove the cover.
  3. Adjust the butterfly valve by loosening the nuts.
  5. The butterfly valve is correctly set when the distance is 2.3 inches (60mm).