Exhaust Gas Recirculation System (EGR)

1. Make a thorough visual check of system, wiping away oil as necessary to facilitate inspection. Replace any cracked or broken hoses.
2. With engine off, check EGR control valve for any indication of binding or sticking by moving diaphragm of control valve upward with finger.
3. Start engine to check EGR control valve and thermal vacuum valve for normal operation.
4. When engine coolant temperature is below 131 'F or above 203'F, ensure that EGR control valve does not operate when engine is raised from idling to 3000-3500 RPM.
5. When engine coolant temperature is between 131 and 203'F, ensure that EGR control valve operates when engine speed is raised from idling to 3000-3500 RPM.
6. If EGR control valve does not operate as described in steps 4 and 5, check as follows:
a. Ensure that coolant temperature is between 131 and 203'F.
b. Increase engine speed from idle to 3000-3500 RPM.
c. Disconnect one end of vacuum gallery for thermal vacuum valve.
d. Ensure that thermal vacuum valve is closed and that throttle chamber vacuum is not present at end of vacuum tube.
e. If vacuum is present, test thermal vacuum valve independently.
f. Test EGR control valve independently.