Exhaust Gas Recirculation: Service and Repair

EGR SYSTEM SERVICE
Whenever the EGR valve is removed, or during regularly scheduled EGR system maintenance, the EGR system should be inspected and cleaned. This will insure that the EGR system will function properly under all operating conditions. Proper EGR system service consists of the following two steps:

EGR System Diagnosis
Diagnosis of the EGR system should be performed if required by engine performance or engine driveability symptoms.

EGR System Cleaning
If the EGR system is operating correctly, the EGR valve and components can be removed, checked for deposits, cleaned, and replaced. Use the procedure below for this operation.

1. Remove the EGR valve from the engine.

2. Hold the valve in your hand. Tap on the end of the round pintle using a light snapping action with a plastic hammer. This will remove the exhaust deposits from the valve seat. Remove all loose particles.

3. Clean the mounting surface of the valve with a wire wheel or wire brush, and the pintle with a wire brush.

4. Depress the valve diaphragm and check the seating area for cleanliness and signs of rubbing by looking through the valve outlet. If pintle or seat are not completely clean, repeat step 2.

5. Hold bottom of valve securely and try to rotate top of valve back and forth. Replace valve if any loosensness is felt.

6. Inspect the valve outlet for deposits. Remove any deposit build-up with a screwdriver of other suitable sharp tool. Do not wash the EGR valve in solvents or degreaser - permanent damage to the valve diaphragm may result. Sand blasting of the valve is not recommended as this may affect proper valve operation.

7. Clean the EGR passages in the intake manifold. Use care to insure that all loose particles are completely removed to prevent them from clogging the EGR valve or being ingested into the engine.

8. Clean the manifold mounting surface. Do not reinstall the EGR valve at this time.

9. Remove the throttle body.

10. Inspect the EGR stack tubes in the floor of the intake manifold for carbon deposits. If necessary, clear the carbon out of the EGR tubes using an 11/32" drill bit. Use caution not to drill into or damage the bottom of the intake manifold.

CAUTION: For the next step, safety glasses must be worn.

11. Cover the top end of one EGR tube with a piece of tape. Hold a shop rag over the EGR valve opening on the manifold. Using compressed air, blow through the uncovered EGR tube to force the carbon debris out through the EGR valve opening in the manifold. Remove the tape from the covered tube.

12. Install the EGR valve using a new gasket.

13. Clean the throttle valves and throttle body passages of all carbon deposits.

14. Reinstall the throttle body using a new gasket.