GM Full Size Vans 1967-1986 Repair Guide

Air Injector Reactor (AIR) System

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This system was first introduced on California vans in 1966. The AIR system injects compressed air into the exhaust system, near enough to the exhaust valves to continue the burning of 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.

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

TESTING



Check Valve

To test the check valve, disconnect the hose at the diverter valve. Blow into the hose and suck on it. Air should flow only into the engine.

Diverter Valve

Pull off the vacuum line to the top of the valve with the engine running. There should be vacuum in the line. Replace the line. No air should be escaping with the engine running at a steady idle. Open and quickly close the throttle. A blast of air should come out of the valve muffler for at least one second.

Air Pump

Disconnect the hose from the diverter valve. Start the engine and accelerate it to about 1,500 rpm. The air flow should increase as the engine is accelerated. If no air flow is noted or it remains constant, check the following:

  1. Drive belt tension.
  2.  
  3. Listen for a leaking pressure relief valve. If it is defective, replace the whole relief/diverter valve.
  4.  
  5. Foreign matter in pump filter openings. If the pump is defective or excessively noisy, it must be replaced.
  6.  

SERVICE



All hoses and fittings should be inspected for condition and tightness of connections. Check the drive belt for wear and tension periodically.

The AIR system is not completely silent under normal conditions. Noises will rise in pitch as engine speed increases. If the noise is excessive, eliminate the air pump itself by disconnecting the drive belt. If the noise disappears, the air pump is not at fault.

REMOVAL & INSTALLATION

  1. Disconnect the output hose.
  2.  
  3. Hold the pump from turning by squeezing the drive belt.
  4.  
  5. Loosen the pulley bolts.
  6.  
  7. Loosen the alternator so the belt can be removed.
  8.  
  9. Remove the pulley.
  10.  
  11. Remove the pump mounting bolts and the pump.
  12.  

To install:
  1. Install the pump with the mounting bolts loose.
  2.  
  3. Install the pulley and tighten the bolts finger tight.
  4.  
  5. Install and adjust the drive belt.
  6.  
  7. Squeeze the drive belt to prevent the pump from turning.
  8.  
  9. Torque the pulley bolts to 25 ft. lbs. (33 Nm). Tighten the pump mountings.
  10.  
  11. Check and adjust the belt tension again, if necessary.
  12.  
  13. Connect the hose.
  14.  
  15. If any hose leaks are suspected, pour soapy water over the suspected area with the engine running. Bubbles will form wherever air is escaping.
  16.  

FILTER REPLACEMENT



  1. Disconnect the air and vacuum hoses from the diverter valve.
  2.  
  3. Loosen the pump pivot and adjusting bolts and remove the drive belt.
  4.  
  5. Remove the pivot and adjusting bolts from the pump. Remove the pump and the diverter valve as an assembly.
  6.  


WARNING
Do not clamp the pump in a vise or use a hammer or prybar on the pump housing.

  1. To change the filter, break the plastic fan from the hub. It is seldom possible to remove the fan without breaking it.
  2.  
  3. Remove the remaining portion of the fan filter from the pump hub. Be careful that filter fragments do not enter the air intake hole.
  4.  
  5. Position the new centrifugal fan filter on the pump hub. Place the pump pulley against the fan filter and install the securing screws. Torque the screws alternately to 95 in. lbs. (10 Nm) and the fan filter will be pressed onto the pump hub.
  6.  
  7. Install the pump on the engine and adjust its drive belt.
  8.  

 
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