GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Air Injection Reactor System (A.I.R.)

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OPERATION



See Figure 1

The AIR system injects compressed air into the exhaust system, near enough to the exhaust valves to continue burning the normally unburned segment of the exhaust gases. To do this it employs an air injection pump and a system of hoses, valves, tubes, etc., necessary to carry the compressed air from the pump to the exhaust manifolds. Carburetors and distributors for AIR engines have specific modifications to adapt them to the air injection system; those components should not be interchanged with those intended for use on engines that do not have the system.

A diverter valve is used to prevent backfiring. The valve senses sudden increases in manifold vacuum and ceases the injection of air during fuel rich periods. During coasting, this valve diverts the entire air flow through the pump muffler and during high engine speeds, expels it through a relief valve. Check valves in the system prevent exhaust gases from entering the pump.



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Fig. Fig. 1: AIR system

The AIR system on the V6 engines is slightly different, but its purpose remains the same.

SERVICE

The AIR system's effectiveness depends on correct engine idle speed and ignition timing. These settings should be strictly adhered to and checked frequently. All hoses and fittings should be inspected for condition and tightness of connections. Check the drive belt for wear and tension every 12 months or 12,000 miles.

REMOVAL & INSTALLATION



See Figures 2, 3 and 4

Air Pump

CAUTION
Do not pry on the pump housing or clamp the pump in a vise; the housing is soft aluminum and may become distorted.

  1. Disconnect the negative (-) battery cable and the air hoses at the pump.
  2.  
  3. Hold the pump pulley from turning and loosen the pulley bolts.
  4.  
  5. Loosen the pump mounting bolt and adjustment bracket bolt. Remove the drive belt.
  6.  
  7. Remove the mounting bolts, and then remove the pump.
  8.  

To install:
  1. Position the pump into the mounting brackets and loosely install the bolts.
  2.  
  3. Install the drive belt and adjust the tension to 146 ft. lbs. for a new belt and 90 ft. lbs. for an old belt. Torque the mounting bolts to 25 ft. lbs. (34 Nm).
  4.  
  5. Install and reconnect the pump hoses and electrical connections.
  6.  



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Fig. Fig. 2: Removing the air pump

Pump Filter
  1. Remove the drive belt and pump pulley.
  2.  
  3. Using needlenose pliers, pull the fan/filter unit from the pump hub.
  4.  

Use care to prevent any dirt or fragments from entering the air intake hole. DO NOT insert a screwdriver between the pump and the filter, and do not attempt to remove the metal hub. It is seldom possible to remove the filter without destroying it.



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Fig. Fig. 3: Air pump filter removal

  1. To install a new filter, draw it on with the pulley and pulley bolts. Do not hammer or press the filter onto the pump.
  2.  
  3. Draw the filter down evenly by torquing the bolts alternately. Make sure the outer edge of the filter slips into the housing. A slight amount of interference with the housing bore is normal.
  4.  

The new filter may squeal initially until the sealing lip on the pump outer diameter has worn in.



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Fig. Fig. 4: Common air pump mounting and location

Diverter (Anti-Afterburn) Valve
  1. Detach the vacuum sensing line and electrical connections from the valve.
  2.  
  3. Remove the other hose(s) from the valve.
  4.  
  5. Unfasten the diverter valve from the elbow or the pump body.
  6.  

To install:
  1. Always use a new gasket. Tighten the valve securing bolts to 85 inch lbs. (10 Nm).
  2.  

 
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