EGR System Cleaning

Whenever the EGR valve is removed, the EGR system should be inspected and cleaned, if necessary. This will ensure that the EGR system will function properly during all operating conditions. Proper EGR system service consists of the following 5 steps.

1. EGR system diagnosis: Diagnosis of the EGR system should be performed if PCM DTCs are set. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article.
2. EGR valve pipe cleaning and checking for leaks: Clean and check the EGR pipe from the exhaust manifold to the EGR valve and the EGR pipe from the water pump crossover to the throttle body spacer.
3. EGR valve cleaning: If the EGR system is operating correctly, the EGR valve can be removed, checked for deposits, cleaned, and re-installed. Use the procedure below for this operation.
   • Remove the EGR valve from the engine. See EGR VALVE .
   • While holding the EGR valve in your hand, use a pencil eraser or other suitable soft instrument to depress the pintle several times. The pintle should move in and out smoothly. Replace any valve that exhibits tendencies to stick.
   • While holding the EGR valve base in your hand, try to rotate the connector housing. Repeat this procedure for the coil housing. Replace any valve that exhibits looseness.
   • Inspect the EGR valve pintle and the valve seat for deposits. Use a cloth or other suitable soft device in order to remove the deposits. Remove all loose particles. If the deposits are such that pintle/base interface cannot be cleaned adequately to allow the pintle to seal against the seat, replace the valve. Damage to the powdered metal EGR valve base will occur if the valve base is cleaned with solvents, sharp tools, a wire brush or wheel, or by sand blasting. Cleaning by these methods is not recommended.
   • Inspect the passage in the water crossover assembly for deposits. Remove all loose particles.
   • Replace EGR valve on the engine using a NEW gasket.
4. Cleaning the EGR passages in the water crossover assembly: Remove the water crossover assembly. See appropriate article in ENGINES. Remove the 2 plugs and clean the passages with a wire brush. See Fig 1. Remove all loose particles. Install the water crossover assembly.
5. Wash your hands with soap and water after any contact with deposits from the EGR system.

Fig 1: Locating EGR Passage Plugs (4.0L Is Shown; 3.5L Is Similar)

Courtesy of GENERAL MOTORS CORP.