Cylinder Head Cleaning and Inspection

Tools Required

• J 8089  Carbon Removal Brush. See Special Tools and Equipment .
• J 8001  Dial Indicator Set
• J 9666  Valve Spring Tester. See Special Tools and Equipment .
• J 28410  Gasket Remover. See Special Tools and Equipment .

Fig 1: Removing All Gasket Material From Sealing Surfaces
Courtesy of GENERAL MOTORS CORP.
NOTE: Carefully clean the aluminum gasket surfaces in order to prevent damage to the sealing surfaces. Use only plastic, wood, or dull gasket scrapers, such as J 28410. Follow the manufacturer's recommendations to dissolve gasket materials with chemical agents.
1. Remove all gasket material from the sealing surfaces using the J 28410  . See Special Tools and Equipment .
Fig 2: Removing Carbon From Combustion Chambers
Courtesy of GENERAL MOTORS CORP.
2. Use the J 8089  to clean the carbon from the combustion chambers. See Special Tools and Equipment .
Fig 3: Cleaning All Valve Guide Bushings
Courtesy of GENERAL MOTORS CORP.
3. Using a valve guide bushing brush and solvent, clean all the valve guide bushings.
4. Using a soft brush and solvent, clean the cylinder head:
   • Intake and exhaust parts
   • Intake and exhaust valve seats
Fig 4: Inspecting Cylinder Head For Flatness
Courtesy of GENERAL MOTORS CORP.
5. Inspect the cylinder head for flatness. Using a straight edge and a feeler gage, measure the surfaces contacting the cylinder block and manifolds for warpage. Refer to Engine Mechanical Specifications (LY9)  or Engine Mechanical Specifications (LA3) . If the warpage is greater than the maximum, replace the cylinder head.
6. Inspect for the following in the cylinder head:
   • Cracks in the exhaust ports
   • Cracks in the combustion chambers
   • Cracks to the water jackets
   • Cracks in the valve seats
   • Valve seats for looseness
Fig 5: Identifying Inspection Points For Valves Damage
Courtesy of GENERAL MOTORS CORP.
7. Use a buffing wheel to clean the valve stems and the valve heads.
8. Inspect the valves for the following:
   • Burnt or damaged areas (1)
   • Undersized valve margin (2)
   • Bent stems (3)
   • Scoring or other damage to the stem (4)
   • Worn key groove (5)
   • Worn stem tip (6)
Fig 6: Inspecting Valve Face For Burning, Pitting & Cracking
Courtesy of GENERAL MOTORS CORP.
9. Inspect the valve contact surface for the following conditions:
   • Undersized margin (1)
   • Pitted surface (2)
   • Burnt or eroded areas (3)
   • Acceptable edge, margin, (4)
IMPORTANT: Minor imperfections of the valve may be corrected during reconditioning.
10. Valves with excessive damage must be replaced.
Fig 7: Inspecting Valve Stem
Courtesy of GENERAL MOTORS CORP.
11. Perform the following steps to inspect the valve stem, 1 to valve guide, 2 clearance:
    • Clamp the J 8001  on the exhaust port side of the cylinder head.
    • Locate the indicator so the movement of the valve stem crosswise to cylinder head will cause a direct movement of the indicator stem.
    • Drop the valve head 10 mm (0.39 in) off the valve seat.
    • Using light pressure to move the stem of the valve side to side to obtain a clearance reading. Refer to Engine Mechanical Specifications (LY9)  or Engine Mechanical Specifications (LA3) .
Fig 8: Measuring Valve Stem
Courtesy of GENERAL MOTORS CORP.
12. Measure the valve stem in 3 locations if the valve clearance is out of specifications.
    • Replace the valve if the valve stem is out of specification.
    • Ream the valve guide and use an oversized valve if the valve stem is within specification.
Fig 9: Inspecting Valve Spring For Squareness
Courtesy of GENERAL MOTORS CORP.
13. Inspect the valve springs for broken coils or coil ends.
14. Perform the following steps to inspect the valve for squareness:
    • Place the valve spring on a level surface next to a square.
    • Rotate the valve spring.
    • Replace the valve spring if the valve spring is more than 1.58 mm (0.062 in) out of square.
Fig 10: Measuring Valve Spring Tension
Courtesy of GENERAL MOTORS CORP.
15. Using calipers, measure the free length of the valve spring. Refer to Engine Mechanical Specifications (LY9)  or Engine Mechanical Specifications (LA3) .
16. Use the J 9666  in order to measure the valve spring force. See Special Tools and Equipment . Refer to Engine Mechanical Specifications (LY9)  or Engine Mechanical Specifications (LA3) .