Major Technical Changes For 1984 Model Vehicles (CAT. 16, NO. 184/83)

Publication date: 1983-09-02
Reference number: CAT. 16, NO. 184/83

MAJOR TECHNICAL CHANGES FOR 1984 MODEL VEHICLES

TECHNICAL SERVICE BULLETIN

Reference Number(s): CAT. 16, NO. 184/83, Date of Issue: 9/2/83

MAJOR CHANGES FOR 1984 MODELS

Model(s): As Listed Below

Bulletin No. 184/83

Category: 16

Date: 9/2/83

DESCRIPTION

This service bulletin contains the major technical changes for the 1984 models listed below.

GLC
1. Emission Control System
2. Cooling System
3. Fuel System
626
1. Emission Control System
B2000
1. Emission Control System
B2200
1. Intake Shutter Valve System
1. GLC
  1. EMISSION CONTROL SYSTEM
    1. EGR SYSTEM
      Vacuum Delay Valve and Orifice
      
      A vacuum delay valve has been added to both MTX and ATX models to improve driveability. They delay EGR operation during initial acceleration (Fig 1 ).
      
      Fig 1: Delay Valve Installation
    1. DECELERATION CONTROL SYSTEM
      AAV (Anti-Afterburn Valve)
      
      An anti-afterburn valve has been added to the ATX models to improve driveability during acceleration. The AAV allows air into the intake manifold to prevent a rich mixture during declaration (Fig 2 ).
      
      Fig 2: View of AAV (Anti-Afterburn Valve)
  2. COOLING SYSTEM
    The operating temperatures for the cooling fan switch and thermostat have been changed to improve driveability during extreme hot weather operation (Fig 3 ).
    
    Fig 3: Cooling Fan Wiring Diagram
    
    Fig 4: WATER TEMPERATURE SWITCH & THERMOSTAT SPECS
  3. FUEL SYSTEM
    Fuel Return Line
    
    On the 1984 model GLC, fuel returns to the fuel tank from the carburetor and not from I the fuel pump as in previous years. This improves driveability during hot under hood conditions
    
    (Fig 5 ).
    
    Fig 5: Check Valve Location
    
    Check Valve
    
    With the above change, a fuel check valve has been added in the fuel return line to prevent fuel from flowing back into the carburetor from the fuel tank (Fig 5 ).
2. 626
  1. EMISSION CONTROL SYSTEM
    1. EGR SYSTEM
    Vacuum Delay Valve and Orifice
    
    A vacuum delay valve and an orifice have been added to the ATX models in the vacuum line to the duty solenoid valve to improve driveability. It delays EGR during initial acceleration (Fig 6 )
    
    Fig 6: Delay Valve & Orifice Locations
3. B2000
  1. EMISSION CONTROL SYSTEM
    1. AIR INJECTION SYSTEM (FEDERAL)
      Reed Valves
      
      Two reed valves are now used on Federal M/T models and three reed valves are used on Federal A/T models to aid in the reduction of HC & CO (Fig 7 ).
    2. EGR SYSTEM (FEDERAL)
      
      Fig 7: Reed Valve Locations
      
      Two EGR valves/are used on B2000 Federal Models for more precise control of EGR. The EGR solenoid valve will cut vacuum to the No. 2 EGR valve when radiator temperature is below 17° +/- 2°C (63 +/- 3.6°F) or when intake manifold temperature is below 50°+/- 2°C (122 +/- 36°F). See Fig 8 .
      
      Fig 8: EGR System Diagram
    3. THROTTLE POSITIONER SYSTEM
    4. (FEDERAL A/T)
      Double Acting Servo Diaphragm
      
      Water Thermo Switch (Rad)
      
      Fast Idle Solenoid Valve
      
      The fast idle solenoid is controlled by the water thermo switch (intake manifold), control unit and water thermoswitch (radiator) When radiator coolant temperature is below 17° (63°F), intake manifold coolant temperature is below 6706 (152°F) and engine rpm is below 1500 rpm, vacuum will be applied to the servo diaphragm through hose "B" and engine speed should increase to 1300 +/- 100 rpm (Fig 9 ).
      
      Fig 9: Thrrttle Positioner System Diagram (Federal A/T)
    5. THROTTLE POSITIONER SYSTEM
    6. (CANADA A/T)
      Water Thermo Switch
      
      A water thermo switch located in the intake manifold has been added to the Throttle Positioner System. (When engine coolant temperature is below 55° +/- 2°(131 +/- 36°F) the thermo switch will open and increase engine idling speed to 1100 rpm). See Fig 10 .
      
      Fig 10: Throtle Positioner System Diagram (Canada A/T)
    7. PRIMARY AIR SUPPLY SYSTEM
    8. (FEDERAL)
      A Primary Air Supply System has been adopted on Federal Models only, to lean the mixture when:
    - Radiator Coolant Temperature above 17°(63°F).
    - Intake Manifold Coolant Temperature below 50°(122°F) and engine rpm is above 1200 rpm,(Fig 11 ).
      
      Fig 11: Primary Air Supply System Diagram
4. B200
  1. INTAKE SHUTTER VALVE SYSTEM
    The intake shutter valve has been eliminated