Chrysler Full-Size Vans 1989-1998 Repair Guide

Air Injection System

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OPERATION



See Figures 1 and 2

The air injection system is used to inject fresh air into the exhaust manifolds or catalytic converters via an air control valve. The air is created by a air pump that is driven by the engine, it is located in the front of the engine and is propelled by a belt. 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.

The system uses a diverter valve which is used to prevent backfire in the exhaust system during sudden deceleration. When the throttle is suddenly closed, a too-rich air/fuel mixture may be created which could not normally be burned. This mixture becomes burnable when it reaches the exhaust area and combines with the injected air. The diverter valve senses the sudden increase in the intake manifold vacuum causing the valve to open, allowing air from the air pump to pass through the valve and silencer into the atmosphere.



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Fig. Fig. 1: Secondary Air Injection system-3.9L engine



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Fig. Fig. 2: Secondary Air Injection system-5.2L and 5.9L engines

Component TESTING

Do not attempt to correct pump noise by lubricating the air pump. Never lubricate the air pump. Do not assume a pump is bad just because it's noisy.

Normally Closed Air Bypass Valve Functional Test
  1. Remove the engine cover.
  2.  
  3. Disconnect the air supply hose at the valve.
  4.  
  5. Run the engine to normal operating temperature.
  6.  
  7. 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.
  8.  
  9. 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.
  10.  
  11. 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.
  12.  
  13. If the valve doesn't pass each of these tests, replace it.
  14.  
  15. Install the engine cover.
  16.  

Normally Open Air Bypass Valve Functional Test
  1. Remove the engine cover.
  2.  
  3. Disconnect the air supply hose at the valve.
  4.  
  5. Run the engine to normal operating temperature.
  6.  
  7. Disconnect the vacuum lines from the valve.
  8.  
  9. 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.
  10.  
  11. Shut off the engine. Using a spare length of vacuum hose, connect the vacuum nipple of the valve to direct manifold vacuum.
  12.  
  13. 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.
  14.  
  15. 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.
  16.  
  17. If the valve doesn't pass each of these tests, replace it. Reconnect all lines.
  18.  
  19. Install the engine cover.
  20.  

Air Control Valve Functional Test
  1. Remove the engine cover.
  2.  
  3. Run the engine to normal operating temperature, then increase the speed to 1,500 rpm.
  4.  
  5. Disconnect the air supply hose at the valve inlet and verify that there is airflow present.
  6.  
  7. Reconnect the air supply hose.
  8.  
  9. Disconnect both air supply hoses.
  10.  
  11. Disconnect the vacuum hose from the valve.
  12.  
  13. 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.
  14.  
  15. Shut off the engine.
  16.  
  17. 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.
  18.  
  19. If the valve is not functioning properly, replace it.
  20.  
  21. Install the engine cover.
  22.  

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 in. (13mm) at most.
  2.  
  3. Remove the engine cover.
  4.  
  5. Run the engine to normal operating temperature and let it idle.
  6.  
  7. 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.
  8.  
  9. Install the engine cover.
  10.  

REMOVAL & INSTALLATION



Air Injection Pump

See Figures 3 and 4

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Remove the drive belt.
  6.  
  7. Remove the air hose from the air pump control valve (the elbow protruding from the pump).
  8.  
  9. Remove the pivot and adjusting bolts from the pump and bracket.
  10.  
  11. Remove the pump from the vehicle.
  12.  

To install:
  1. Install the pump on the mounting bracket and tighten the bolts to 30 ft. lbs. (41 Nm).
  2.  
  3. Install the air hose onto the pump control valve.
  4.  
  5. Install the drive belt.
  6.  
  7. Install the engine cover.
  8.  
  9. Connect the negative battery cable.
  10.  



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Fig. Fig. 3: Typical air pump-3.9L model shown



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Fig. Fig. 4: Exploded view of an air pump mounting at the front of an engine

Centrifugal Filter Fan

See Figures 5 and 6

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Remove the air pump drive belt.
  6.  
  7. Remove the air pump pulley.
  8.  
  9. Insert a pair of needlenose pliers between the plastic filter fins and break the fan from the hub.
  10.  

It is nearly impossible to not destroy the fan on removal. Take care to avoid getting pieces in the air intake hole.

  1. Pry the fan off the hub.
  2.  

To install:
  1. Install the new fan over the hub.
  2.  
  3. Install the pulley over the fan. Start to tighten the air pump pulley bolts alternately, drawing the fan all the way onto the hub.
  4.  

A slight amount of interference with the housing bore is normal, and the pump may squeal upon replacement, usually this will go away in 20-30 miles (32-48 km) after the outer sealing lip has worn.

  1. Tighten the pulley bolts on the air pump to 9 ft. lbs. (11 Nm).
  2.  
  3. Install the air pump drive belt.
  4.  
  5. Install the engine cover.
  6.  
  7. Connect the negative battery cable.
  8.  



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Fig. Fig. 5: Use needlenose pliers to break away a damaged fan from the hub



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Fig. Fig. 6: Tighten down the air pump pulley to seat the fan

Diverter Valve

See Figure 7

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Remove the air and vacuum hoses from the diverter valve.
  6.  
  7. Remove the valve mounting bolts.
  8.  
  9. Remove the valve from the mounting flange.
  10.  

To install:
  1. Thoroughly clean gasket material off the mounting flange.
  2.  
  3. Position new gasket on the mounting flange.
  4.  
  5. Position diverter valve on mounting flange and tighten bolts to 95 inch lbs. (11 Nm).
  6.  
  7. Install the air and vacuum hoses.
  8.  
  9. Install the engine cover.
  10.  
  11. Connect the negative battery cable.
  12.  



Click image to see an enlarged view

Fig. Fig. 7: Internal and external details of the diverter valve

Switch/Relief Valve

See Figure 8

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Remove the air and vacuum hoses from pump.
  6.  
  7. Remove the valve mounting bolts.
  8.  
  9. Remove the valve.
  10.  

To install:
  1. Thoroughly clean the valve mounting flange of gasket material.
  2.  
  3. Position new gasket on mounting flange.
  4.  
  5. Position new relief valve on flange and tighten to 95 inch lbs. (11 Nm).
  6.  
  7. Install air and vacuum hoses to valve.
  8.  
  9. Install the engine cover.
  10.  
  11. Connect the negative battery cable.
  12.  



Click image to see an enlarged view

Fig. Fig. 8: Details of the switch/relief valve

Check Valve
non-threaded type
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Release the clamp, and remove the hose from check valve inlet.
  6.  
  7. Remove the bolts or tube nut securing injection tube to the exhaust manifolds or exhaust pipe.
  8.  
  9. Remove the infection tube assembly from the vehicle.
  10.  

To install:
  1. Thoroughly clean the gasket surface on the exhaust manifold and injection tube flanges.
  2.  
  3. Install new gaskets on exhaust manifold flanges and install injection tube assembly.
  4.  
  5. Tighten the tube bracket and flange mounting bolts to 200 inch lbs. (23 Nm). Tighten the tube nut joint assembly to 24-35 ft. lbs. (34-37 Nm).
  6.  
  7. Install the inlet hose and tighten clamp.
  8.  
  9. Install the engine cover.
  10.  
  11. Connect the negative battery cable.
  12.  

Threaded type
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Release clamp and remove hose from valve inlet.
  6.  
  7. Unscrew the check valve from the injection tube.
  8.  

To install:
  1. Install check valve onto injection tube assembly and tighten to 25 ft. lbs. (34 Nm).
  2.  
  3. Install the air hose onto the valve inlet and tighten the clamp.
  4.  
  5. Install the engine cover.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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