Chrysler Full-Size Vans 1967-1988 Repair Guide

Air Injection System

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OPERATION



See Figures 1 through 7

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Fig. Fig. 1: Example of an early air injection system for a V8 engine



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Fig. Fig. 2: Air injection system used on 1980-82 inline cylinder engines



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Fig. Fig. 3: Air injection system used on 1984 V8 engines



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Fig. Fig. 4: Air injection system for 1984-88 inline 6-cylinder engines



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Fig. Fig. 5: Dual air pump air injection system used on some vehicles-1986 318 engine shown, others are similar



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Fig. Fig. 6: Air injection system used on the 1988 238 engine



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Fig. Fig. 7: Air injection system used on 1988 318 and 360 engines

The air injection emission control system makes use of a belt driven air pump to inject fresh air into the hot exhaust stream through the engine exhaust ports. The result is the extended burning of those fumes which were not completely ignited in the combustion chamber, and the subsequent reduction of some of the hydrocarbon and carbon monoxide content of the exhaust emissions into harmless carbon dioxide and water.

The air injection system is composed of the following components:

  1. Air supply pump (belt driven)
  2.  
  3. Air by-pass valve.
  4.  
  5. Check valves
  6.  
  7. Air manifolds (internal or external)
  8.  
  9. Air supply tubes (on external manifolds only).
  10.  

Air for the air injection system is cleaned by means of a centrifugal filter fan mounted on the air pump driveshaft. The air filter does not require a replaceable element.

To prevent excessive pressure, the air pump is equipped with a pressure relief valve which uses a replaceable plastic plug to control the pressure setting.

The air injection air pump has sealed bearings which are lubricated for the life of the unit, and preset rotor vane and bearing clearances, which do not require any periodic adjustments.

The air supply from the pump is controlled by the air by-pass valve, sometimes called a dump valve. During deceleration, the air bypass valve opens, momentarily diverting the air supply through a silencer and into the atmosphere, thus preventing backfires within the exhaust system.

A check valve is incorporated in the air inlet side of the air manifolds. Its purpose is to prevent exhaust gases from backing up into the air injection system. This valve is especially important in the event of drive belt failure, and during deceleration, when the air by-pass valve is dumping the air supply.

The air manifolds and air supply tubes channel the air from the air injection air pump into the exhaust ports of each cylinder, thus completing the cycle of the air injection system

DIAGNOSIS & TESTING



The air injection system is used to inject fresh air into the exhaust manifolds or catalytic converters via an air control valve. Under some operating conditions, the air can be dumped back into the atmosphere via an air bypass valve. On some applications the two valves are combined into one unit. The air bypass valve can be either the normally closed type, when the valves are separate, or the normally open type, when the valves are combined.

Normally Closed Air Bypass Valve Functional Test
  1. Disconnect the air supply hose at the valve.
  2.  
  3. Run the engine to normal operating temperature.
  4.  
  5. Disconnect the vacuum line and make sure vacuum is present. If no vacuum is present, remove or bypass any restrictors or delay valves in the vacuum line.
  6.  
  7. Run the engine at 1,500 rpm with the vacuum line connected. Air pump supply air should be heard and felt at the valve outlet.
  8.  
  9. With the engine still at 1,500 rpm, disconnect the vacuum line. Air at the outlet should shut off or dramatically decrease. Air pump supply air should now be felt or heard at the silencer ports.
  10.  
  11. If the valve doesn't pass each of these tests, replace it.
  12.  

Normally Open Air Bypass Valve Functional Test
  1. Disconnect the air supply hose at the valve.
  2.  
  3. Run the engine to normal operating temperature.
  4.  
  5. Disconnect the vacuum lines from the valve.
  6.  
  7. Run the engine at 1,500 rpm with the vacuum lines disconnected. Air pump supply air should be heard and felt at the valve outlet.
  8.  
  9. Shut off the engine. Using a spare length of vacuum hose, connect the vacuum nipple of the valve to direct manifold vacuum.
  10.  
  11. Run the engine at 1,500 rpm. Air at the outlet should shut off or dramatically decrease. Air pump supply air should now be felt or heard at the silencer ports.
  12.  
  13. With the engine still in this mode, cap the vacuum vent. Accelerate the engine to 2,000 rpm and suddenly release the throttle. A momentary interruption of air pump supply air should be felt at the valve outlet.
  14.  
  15. If the valve doesn't pass each of these tests, replace it. Reconnect all lines.
  16.  

Air Control Valve Functional Test
  1. Run the engine to normal operating temperature, then increase the speed to 1,500 rpm.
  2.  
  3. Disconnect the air supply hose at the valve inlet and verify that there is airflow present.
  4.  
  5. Reconnect the air supply hose.
  6.  
  7. Disconnect both air supply hoses.
  8.  
  9. Disconnect the vacuum hose from the valve.
  10.  
  11. With the engine running at 1,500 rpm, airflow should be felt and heard at the outlet on the side of the valve, with no airflow heard or felt at the outlet opposite the vacuum nipple.
  12.  
  13. Shut off the engine.
  14.  
  15. Using a spare piece of vacuum hose, connect direct manifold vacuum to the valve's vacuum fitting. Airflow should be heard and felt at the outlet opposite the vacuum nipple, and no airflow should be present at the other outlet.
  16.  
  17. If the valve is not functioning properly, replace it.
  18.  

Air Supply Pump Functional Check
  1. Check and, if necessary, adjust the belt tension. Press at the mid-point of the belt's longest straight run. You should be able to depress the belt about 1 / 2 " at most.
  2.  
  3. Run the engine to normal operating temperature and let it idle.
  4.  
  5. Disconnect the air supply hose from the bypass control valve. If the pump is operating properly, airflow should be felt at the pump outlet. The flow should increase as you increase the engine speed. The pump is not serviceable and should be replaced if it is not functioning properly.
  6.  

REMOVAL & INSTALLATION



Air By-Pass Valve
  1. Disconnect the air and vacuum hoses at the air by-pass valve body.
  2.  
  3. Position the air by-pass valve and connect the respective hoses.
  4.  

Check Valve
  1. Disconnect the air supply hose at the valve. Use a 1 1 / 4 " crowfoot wrench. The valve has a standard, right-hand pipe thread.
  2.  
  3. Clean the threads on the air manifold adapter (air supply tube on the V8 engines) with a wire brush. Do not blow compressed air through the check valve in either direction.
  4.  
  5. Install the check valve and tighten.
  6.  
  7. Connect the air supply hose.
  8.  

Air Manifold
6-CYLINDER ENGINES ONLY
  1. Disconnect the air supply hose at the check valve, position the hose out of the way and remove the valve.
  2.  
  3. Loosen all of the air manifold-to-cylinder head tube coupling nuts (compression fittings). Inspect the air manifold for damaged threads and fittings and for leaking connections. Repair or replace as required. Clean the manifold and associated parts with kerosene. Do not dry the parts with compressed air.
  4.  
  5. Position the air manifold on the cylinder head. Be sure that all of the tube coupling nuts are aligned with the cylinder head.
  6.  
  7. Screw each coupling nut into the cylinder head, one or two threads. Tighten the tube coupling nuts.
  8.  
  9. Install the check valve and tighten it.
  10.  
  11. Connect the air supply hose to the check valve.
  12.  

Air Supply Tube
V8 ENGINE ONLY
  1. Disconnect the air supply hose at the check valve and position the hose out of the way.
  2.  
  3. Remove the check valve.
  4.  
  5. Remove the air supply tube bolt and seal washer.
  6.  
  7. Carefully remove the air supply tube and seal washer from the cylinder head. Inspect the air supply tube for evidence of leaking threads or seal surfaces. Examine the attaching bolt head, seal washers, and supply tube surface for leaks. Inspect the attaching bolt and cylinder head threads for damage. Clean the air supply tube, seal washers, and bolt with kerosene. Do not dry the parts with compressed air.
  8.  
  9. Install the seal washer and air supply tube on the cylinder head. Be sure that it is positioned in the same manner as before removal.
  10.  
  11. Install the seal washer and mounting bolt. Tighten the bolt.
  12.  
  13. Install the check valve and tighten it.
  14.  
  15. Connect the air supply hose to the check valve.
  16.  

Air Nozzle
6-CYLINDER ENGINES ONLY

Normally, air nozzles should be replaced during cylinder head reconditioning. A nozzle may be replaced, however, without removing the cylinder head, by removing the air manifold and using a hooked tool.

Clean the nozzle with kerosene and a stiff brush. Inspect the air nozzles for eroded tips.

Air Pump and Filter

Fan

  1. Loosen the air pump attaching bolts.
  2.  
  3. Remove the drive pulley attaching bolts and pull the pulley off the air pump shaft.
  4.  
  5. Pry the outer disc loose, then remove the centrifugal filter fan. Care must be used to prevent foreign matter from entering the air intake hole, especially if the fan breaks during removal. Do not attempt to remove the metal drive hub.
  6.  
  7. Install the new filter fan by drawing it into position with the pulley bolts.
  8.  

Some 1967 air pumps have air filters with replaceable, non-cleanable elements.

Air Pump
  1. Disconnect the air outlet hose at the air pump.
  2.  
  3. Loosen the pump belt tension adjuster.
  4.  
  5. Disengage the drive belt.
  6.  
  7. Remove the mounting bolt and air pump.
  8.  
  9. Position the air pump on the mounting bracket and install the mounting bolt.
  10.  
  11. Place the drive belt in the pulley and attach the adjusting arm to the air pump.
  12.  
  13. Adjust the drive belt tension and tighten the adjusting arm and mounting bolts.
  14.  
  15. Connect the air outlet hose to the air pump.
  16.  

Relief Valve

Do not disassemble the air pump on the truck to replace the relief valve, but remove the pump from the engine.

  1. Remove the relief valve on the pump housing and hold it in position with a block of wood.
  2.  
  3. Use a hammer to lightly tap the wood block until the relief valve is seated.
  4.  

Relief Valve Pressure Setting Plug
  1. Compress the locking tabs inward (together) and remove the plastic pressure setting plug.
  2.  
  3. Before installing the new plug, be sure that the plug is the correct one. The plugs are color coded.
  4.  
  5. Insert the plug in the relief valve hole and push in until it snaps into place.
  6.  

 
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