Chrysler Full-Size Trucks 1967-1988 Repair Guide

Exhaust Gas Recirculation System

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OPERATION Ported EGR

See Figures 1, 2 and 3

The ported EGR valve is operated by engine vacuum. A vacuum signal from the carburetor or throttle body activates the EGR valve diaphragm. As the vacuum signal increases, it gradually opens the valve pintle allowing exhaust gases to flow. The amount of flow is directly proportional to the pintle position.



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Fig. Fig. 1: EGR system on 1979-85 models



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Fig. Fig. 2: EGR time delay system



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Fig. Fig. 3: EGR and back pressure transducer assembly

Heated Air Intake

See Figure 4

The 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 returned to the atmosphere via an air bypass valve. On some applications, the two valves are combined into one unit. The bypass valve can be either the normally-closed type (if the 2 valves are separate) or the normally-open type (if the valves are combined).



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Fig. Fig. 4: Heated air inlet system

COMPONENT TESTING



EGR System
  1. The engine should be warmed up, at normal operating temperature, with the parking brake set.
  2.  
  3. Allow the engine to idle in Neutral with the throttle closed, then quickly accelerate to approximately 2000 rpm, watching the groove carefully on the EGR valve stem.
  4.  
  5. You should notice movement of the valve stem during the acceleration period, and there should be a change in the location of the groove on the stem. If movement is noticed this means that the control system is functioning properly and the EGR flow test can be performed.
  6.  
  7. If no movement is noticed, you may have to replace the valve or another component in the system.
  8.  

EGR Gas Flow
  1. Connect a tachometer to the engine.
  2.  
  3. Remove the vacuum hose from the EGR valve and connect a hand vacuum pump to the valve vacuum motor nipple.
  4.  
  5. Start the engine and slowly apply vacuum to the motor.
  6.  
  7. The engine rpm should drop as the vacuum reaches 3-5 in. Hg (10-17 kPa), and continue to drop as more vacuum is applied. Your engine may even stall out during this test (meaning that EGR gases are flowing through the system).
  8.  
  9. If this and system tests are good, your EGR system is fully functioning.
  10.  
  11. If the rpm does not drop, the valve may be plugged or defective. If so, remove the valve and inspect it, along with the intake manifold passages for any deposits. Clean if necessary.
  12.  

EGR VACUUM HOSE ROUTING



See Figures 5 through 26

The accompanying illustrations pertain specifically to EGR vacuum hoses. Additional vacuum circuits are found at the end of this section.



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Fig. Fig. 5: EGR vacuum hose routings for 6-225 engines-1974 California D100/W100 models



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Fig. Fig. 6: EGR vacuum hose routings for 8-318 engines with a ported system-1974 non-California D100/W100 models



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Fig. Fig. 7: EGR vacuum hose routings for 8-318 engines-1974 California D100 models



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Fig. Fig. 8: EGR vacuum hose routings for 8-360 engines-1974 non-California D100/W100 models



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Fig. Fig. 9: EGR vacuum hose routings for 8-360 engines-1974 California D100/W100 models



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Fig. Fig. 10: EGR vacuum hose routings for 8-400 and 440 engines-1974 non-California D100 models



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Fig. Fig. 11: EGR vacuum hose routings for 8-400 and 440 engines-1974 California D100 models



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Fig. Fig. 12: EGR and idle enrichment vacuum hose routings for 6-225 engines equipped with an automatic transmission-1975-76 D100 models



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Fig. Fig. 13: EGR vacuum hose routings for 8-318 engines equipped with a manual transmission-1975-76 D100 and W100 models



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Fig. Fig. 14: EGR vacuum hose routings for 6-225 engines equipped with a manual transmission-1975-76 light duty models



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Fig. Fig. 15: EGR and throttle positioner vacuum hose routings-1975-76 California heavy duty models



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Fig. Fig. 16: EGR vacuum hose routings for 8-440 engines-1975-76 California heavy duty models



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Fig. Fig. 17: EGR vacuum hose routings for 6-225 engines-1977 light duty Ramcharger and Trail Duster models



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Fig. Fig. 18: EGR vacuum hose routings for 8-318 engines equipped with a manual transmission-1977 light duty Ramcharger and Trail Duster models



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Fig. Fig. 19: EGR vacuum hose routings for 8-318 and 360 engines-1977 California heavy duty Ramcharger and Trail Duster models



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Fig. Fig. 20: EGR vacuum hose routings for 8-440 engines-1977 California heavy duty Ramcharger and Trail Duster models



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Fig. Fig. 21: EGR vacuum hose routings for 6-225 engines-all 1979 models



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Fig. Fig. 22: EGR vacuum hose routings for 8-318 engines equipped with a manual transmission-all 1979 models



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Fig. Fig. 23: EGR vacuum hose routings for 8-318 and 360 engines equipped with an automatic transmission-1979 light duty models



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Fig. Fig. 24: EGR vacuum hose routings for 8-318 engines equipped with a manual transmission-all 1980 models



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Fig. Fig. 25: EGR vacuum hose routings for 8-318 and 360 engines equipped with an automatic transmission-1980 light duty models



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Fig. Fig. 26: EGR vacuum hose routings for 8-318 and 360 engines-1980 California heavy duty models

 
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