Cylinder Head Cleaning and Inspection

Special Tools

• J 8089:  Carbon Removal Brush
• J 9666:  Valve Spring Tester

For equivalent regional tools, refer to Special Tools .

Fig 1: Removing Carbon From Combustion Chambers
Courtesy of GENERAL MOTORS CORP.
WARNING: Refer to Safety Glasses Warning .
NOTE:
• When cleaning a cylinder head in a thermal type oven, do not exceed 204°C (400°F).
• Be careful not to scuff the chamber.
1. Clean the following components:
   • Use the J 8089:  brush in order to remove the carbon from the combustion chambers.
   • Gasket surfaces

     Refer to Replacing Engine Gaskets .

   • Valve stems and heads on a buffing wheel
   • Bolt hole threads

     Remove all dirt, debris, or threadlocking material from the bolt holes.

2. Inspect the cylinder head for the following conditions:
   1. Cracks in the exhaust ports and combustion chambers
   2. External cracks in the water chambers
   3. Gasket surfaces for excessive scratches or gouging

      Refer to Replacing Engine Gaskets .

   4. Bolt hole threads for debris or damaged threads

      Refer to Thread Repair  or Thread Repair Specifications .

Fig 2: Inspecting Cylinder Head For Warpage
Courtesy of GENERAL MOTORS CORP.
3. Inspect the cylinder head for warpage. Refer to Engine Mechanical Specifications (RPO L20 VIN A) or Engine Mechanical Specifications (RPO L96 VIN G) or Engine Mechanical Specifications (RPO L9H) or Engine Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical Specifications (RPO LMG VIN 0) or Engine Mechanical Specifications (RPO LY6 VIN K) .
Fig 3: Measuring Valve Spring Tension
Courtesy of GENERAL MOTORS CORP.
4. Use the J 9666:  tester in order to measure the valve spring tension. Refer to Engine Mechanical Specifications (RPO L20 VIN A) or Engine Mechanical Specifications (RPO L96 VIN G) or Engine Mechanical Specifications (RPO L9H) or Engine Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical Specifications (RPO LMG VIN 0) or Engine Mechanical Specifications (RPO LY6 VIN K) .
Fig 4: Identifying Plug
Courtesy of GENERAL MOTORS CORP.
5. Inspect for a leaking plug (1) at the top rear coolant passage of each cylinder head. If service of a leaking plug is required, it is necessary to remove the cylinder head from the engine to properly remove the plug. Refer to Cylinder Head Disassemble .