Exhaust Gas Recirculation: Service and Repair

EGR Valve Flow:

PRECAUTIONS
CAUTION: If EGR passages in the intake manifold indicate excessive build-up of carbon deposits, the passages should be cleaned. Care should be taken to ensure that all loose particles are completely removed to prevent them from clogging the EGR valve, or from being ingested into the engine. Do not use chemicals or solvents to clean the EGR valve or intake manifold passages since chemicals may cause damage to the system. Wear approved eye protection for this cleaning procedure, to avoid possible injury to the eyes.

EGR VALVE INSPECTION AND CLEANING
- Disconnect the vacuum hose from the EGR valve. Remove the EGR valve-to-manifold retaining bolts, and the control valve.
- Carefully plug the EGR ports into the intake manifold with a clean shop towel or other suitable cloth. This will prevent debris from falling into the intake port.
NOTE: Be sure to remove the cloth from the EGR port before installing the valve. Use compressed air to remove small debris.
- With a wire wheel, remove the exhaust deposits from the mounting surface of the EGR valve and around the valve.
- Look for exhaust deposits in the valve outlet, remove deposits as needed.
- Clean intake manifold mounting surface.
- Install valve assembly using new gasket, and reconnect the vacuum hose.

EGR System Components:

Exhaust Gas Recirculation (EGR) Flow:

EGR Piping:

ADDITIONAL EGR SYSTEM CLEANING
A potential drawback with EGR systems is that for certain driving schedules, deposits can accumulate when hot gases are cooled.

The Northstar system uses the crossover water pump housing as a cross-flow heat exchanger to cool exhaust gases in large easily cleaned passages to virtually eliminate any concern with deposit accumulation during the service life of the engine.

NOTE: For cleaning of the EGR Water pump housing, EGR valve pipe, or EGR cylinder distribution tubes refer to the appropriate engine repair section.