#### TESTING

NOTE: A quick service check for the EGR valve operation is with the engine running at idle, push up on the EGR control valve diaphragm with your finger. When this is done, the engine idle should become rough and uneven.

1. Remove the EGR valve and apply enough vacuum to the diaphragm to open the valve.
2. The valve should remain open for over 30 seconds after the vacuum is removed.

   Fig. 1: Removing the EGR valve

   Fig. 2: Quick test for the EGR valve operation

   Fig. 3: Clean seat of the EGR valve with a stiff brush

   Fig. 4: You can apply vacuum to the EGR valve by sucking on the air tube which is connected to it.

   Fig. 5:Some EGR valves may be tested using a vacuum pump by watching for diaphragm movement

   Fig. 6:Example of a thermal vacuum valve — Chevrolet shown

3. Check the valve for damage, such as warpage, cracks, and excessive wear around the valve and seat.
4. Clean the seat with a brush and compressed air and remove any deposits from around the valve and port (seat).
5. To check the operation of the thermal vacuum valve, remove the valve from the engine and apply vacuum to the ports of the valve. The valve should not allow vacuum to pass.
6. Place the valve in a container of water with a thermometer and heat the water. When the temperature of the water reaches 134–145°F (57–63°C), remove the valve and apply vacuum to the ports. The valve should allow vacuum to pass through it.
7. To test the B.P.T. valve, disconnect the two vacuum hoses from the valve. Plug one of the ports. While applying pressure to the bottom of the valve, apply vacuum to the unplugged port and check for leakage. If any exists, replace the valve.
8. To test the check valve, remove the valve and blow into the side which connects the EGR valve. Air should flow. When air is supplied to the other side, air flow resistance should be greater. If not, replace the valve.
9. To check the V.V.T. valve disconnect the top and bottom center hoses and apply a vacuum to the top hose. Check for leaks. If a leak is present, replace the valve.