Cylinder Head Cleaning and Inspection

Tools Required 

J 9666  Valve Spring Tester. See Special Tools and Equipment .

1. Inspect the cylinder head gasket and the mating surfaces for leaks, corrosion, and blowby.
2. If the gasket failed, determine the cause. Gasket failure is caused by the following conditions:
   • Improper installation
   • A loose or warped cylinder head
   • Missing dowel pins
3. Clean the cylinder head of all foreign material. Do not use a motorized wire brush on any gasket sealing surface.
4. Clean the threaded holes.
5. Inspect the cylinder head for cracks typically between the valve seats and inside of the exhaust ports.
   IMPORTANT: Do not attempt to weld the cylinder head. If the cylinder head is damaged, replace the cylinder head.
6. Inspect the cylinder head deck for corrosion.
   Fig 1: View Of Cylinder Head Gasket And Mating Surfaces

   Courtesy of GENERAL MOTORS CORP.
7. Inspect the following locations for flatness:
   • The cylinder head deck
   • The intake manifold mating surface
   • The exhaust manifold mating surface
8. Recondition the surfaces by parallel grinding. Replace the cylinder head if more than 0.254 mm (0.010 in) is removed.
   Fig 2: Reconditioning Surfaces By Parallel Grinding

   Courtesy of GENERAL MOTORS CORP.
9. Measure the height from the deck surface to the cast pads. Do this to determine if the cylinder head has sufficient deck surface thickness to resurface.

   New cylinder heads measure from 1.372-1.676 mm (0.054-0.066 in). If the cylinder head does not meet the minimum thickness after resurfacing, replace the cylinder head.

   Fig 3: Measuring Height From Deck Surface To Cast Pads

   Courtesy of GENERAL MOTORS CORP.
10. Inspect all of the threaded holes for damage. Repair the threaded holes, if necessary.
11. Inspect the valve seating surfaces.
12. Inspect the cooling jacket plugs.
13. Inspect the valve guides for wear. Clean the valve guides.
14. Inspect the valve seats for excessive wear and hot spots.
15. Inspect the valve springs for squareness.
16. Inspect the valve spring ends. If the valve spring ends are not parallel, the valve spring is bent. Replace the bent valve spring.
    Fig 4: Inspecting Valve Springs For Squareness

    Courtesy of GENERAL MOTORS CORP.
17. Using the J 9666  test the valve spring load. Replace the spring if the valve spring load is less than 334 N.m at 43.69 mm (75 lb at 1.72 in).
18. Inspect the valve spring seating surface of the valve spring retainers for wear or gouging. If the seating surface is damaged, replace the valve spring retainers.
19. Use the following procedure to measure the valve seat concentricity:
    1. 19.1. Lift the valve off its seat.
    2. 19.2. Apply a dab of blue dye to the valve face.
    3. 19.3. Seat and rotate the valve.

       The blue dye traces transferred to the valve seat are an indication of concentricity of the valve seat.

       Fig 5: Testing Valve Spring Load

       Courtesy of GENERAL MOTORS CORP.
20. Use the following procedure to measure the valve runout:
    1. 20.1. Clean off the blue dye.
    2. 20.2. Apply blue dye to the valve seat.
    3. 20.3. Seat and rotate the valve.

       The traces of blue dye transferred to the valve indicates valve runout.

    4. 20.4. Recondition the valve seat or valve face, if needed.