Exhaust Gas Recirculation System (EGR)

1. Make a thorough visual check of system, wiping away oil, if necessary, to facilitate inspection.
2. With engine off, inspect EGR control valve(s) for any indication of binding or sticking by moving diaphragm of control valve upward on number 1 valve or downward on number 2 valve with a finger.
3. With engine running, inspect EGR control valve(s), thermal vacuum valve, and EGR vacuum control valve for normal operation.
4. When engine coolant temperature is below 59°F, make sure EGR control valves do not operate when engine speed is increased from idling to 3000-3500 RPM.
5. When engine coolant temperature is above 140°F, make sure EGR control valves operate when engine speed is increased from idling to 3000-3500 RPM.
6. On 1982-83 models, if EGR control valves do not operate properly, proceed as follows:
a. Disconnect EGR control valve side of vacuum hose which connects 3- way connector to No. 1 EGR control valve.
b. Disconnect No. 2 EGR control valve side of vacuum hose which connects No. 2 EGR control valve and EGR vacuum control valve.
c. Increase engine speed from idle to 3000-3500 RPM.
d. Make sure thermal vacuum valve is closed and throttle vacuum for No. 1 EGR control valve or intake manifold vacuum for No. 2 EGR control valve is present at the ends of respective hoses.
7. On 1984 models, if EGR control valve does not operate properly, proceed as follows:
a. Disconnect EGR control valve side of vacuum hose which connects 3-way connector to EGR control valve.
b. Increase engine speed from idle to 3000-3500 RPM.
c. Ensure thermal vacuum valve is closed and throttle vacuum for EGR control valve is present at end of vacuum hose.
8. On all models, if there is little or no vacuum, replace thermal vacuum valve. If there is vacuum, replace EGR control valve(s).
9. If any difficulty is encountered in determining the condition of an individual component, test component independently.