Cylinder Head Cleaning and Inspection (LS3, LS9)

Special Tools

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

  For equivalent regional tools, refer to Special Tools

Fig 1: Cleaning Carbon Using Special Tool
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 (6.2L LS3)Thread Repair (6.2L LS9) or Thread Repair Specifications (6.2L LS3/7.0L)Thread Repair Specifications (6.2L LS9) .

Fig 2: Inspecting Cylinder Head For Warpage
Courtesy of GENERAL MOTORS CORP.
3. Inspect the cylinder head for warpage. Refer to Engine Mechanical Specifications (6.2L LS3) or Engine Mechanical Specifications (6.2L LS9) .
Fig 3: Identifying Machining Pads
Courtesy of GENERAL MOTORS CORP.
4. Cylinder heads that have excessive warpage or a damaged sealing surface can be machined as required. Determine the cylinder head thickness as measured from the cast in place machining pads (1 and 2) to the head deck sealing surface. A cylinder head that measures less than 6.88-7.11 mm (0.271-0.280 in) (a) cannot be machined and must be replaced.
Fig 4: Measuring Valve Spring Tension
Courtesy of GENERAL MOTORS CORP.
5. Use the J 9666:  Tester in order to measure the valve spring tension. Refer to Engine Mechanical Specifications (6.2L LS3) or Engine Mechanical Specifications (6.2L LS9) .
Fig 5: Rivet
Courtesy of GENERAL MOTORS CORP.
6. Inspect for a leaking plug. Production applications use a rivet-type 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