EGR Valve: Testing and Inspection

Testing requirements:
No leaks at vacuum line connections
Vacuum lines not plugged or kinked

1. Start the engine and let it reach normal operating temperature (coolant fan should cycle on and off at least once).
2. Disconnect and plug the yellow vacuum line to the EGR valve.

Fig. 26 Testing EGR Valve (California):

3. Connect a hand operated vacuum pump to the EGR valve.
4. With the engine running, apply 400 mm (16 in.) Hg of vacuum to the valve and observe the results:

a. The engine speed must gradually drop while applying vacuum.
b. The engine speed should return to normal after releasing vacuum from the valve.

5. If the engine speed does not change, the EGR diaphragm may be ruptured or the passage could be blocked.
6. Apply vacuum to the valve and check that EGR valve opens.
7. If there is no movement, replace the EGR valve.
8. If the EGR valve opens, check the EGR line and the ports in the intake and exhaust manifolds for blockage and clean out or repair as necessary.