Exhaust Gas Recirculation: Testing and Inspection

Fig. 25 Testing The EGR System:

EGR SYSTEM INSPECTION

1. Disconnect the green striped vacuum hose from the carburetor body and connect a hand vacuum pump to the disconnected hose.
2. While the engine is cold (coolant temperature less than 45 degrees C or 113 degrees F) apply vacuum and accelerate engine to 3,500 rpm. Verify that vacuum leaks.
3. Allow the engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F).
4. While the engine is idling apply vacuum and verify that vacuum leaks.
5. Accelerate engine to 3,500 rpm and verify that vacuum leaks until it reaches about 11 kPa or 3 in. Hg.

Fig. 26 Testing The EGR Valve:

EGR VALVE INSPECTION

1. Remove the EGR valve from the vehicle and check for sticking, carbon deposits, or obvious damage. If necessary clean the valve with a suitable solvent.
2. Connect a hand vacuum pump to the EGR valve. Apply 67 kPa or 19.4 in. Hg of vacuum and verify that the diaphragm chamber is leak tight.
3. Apply 8 kPa or 2.3 in. Hg of vacuum and verify that air will not pass through the valve.
4. Increase vacuum to 23 kPa or 6.7 in. Hg and verify that air will pass through the valve.
5. Re-install the EGR valve and torque to 7 - 11 Nm or 5 - 8 ft. lbs.

Fig. 14 Connecting A Vacuum Pump To The Thermo Valve:

THERMO VALVE INSPECTION

1. Disconnect the white stripe vacuum hose from the thermo valve.
2. Connect a hand vacuum pump to the thermo valve nipple the vacuum hose was removed from.
3. While the engine is cold (coolant temperature less than 10 degrees C or 50 degrees F) verify that vacuum leaks.
4. Warm up the engine (coolant temperature greater than 25 degrees C or 77 degrees F) and verify that vacuum holds.

Fig. 16 Testing The Thermo Valve:

5. Mark and then disconnect all vacuum hoses from thermo valve. Connect a hand vacuum pump to nipples 'B', 'C', and 'D' one at a time and plug all the other nipples.
6. While the engine is cold (engine coolant temperature less than 40 degrees C or 104 degrees F) apply vacuum and verify that vacuum leaks.
7. Warm up the engine (coolant temperature greater than 80 degrees C or 176 degrees F) and verify that vacuum holds.