Cylinder Head Assembly: Service and Repair

Cylinder Head Replacement

Valve Train And Cylinder Head:

Cleaning Valve Guide:

Checking Cylinder Head Flatness:

Cylinder Head Bolt Tightening Sequence:

Important: Before removing the cylinder head(s) from the engine and before disassembling the valve mechanism, perform a compression test and record the results.

Remove or Disconnect

1. Negative battery cable.
2. Serpentine belt.
3. From left cylinder head:
- Generator with wiring attached and lay aside.
- Air conditioning compressor with hoses attached and lay aside.
- Bracket with power steering pump and lay aside.
4. From right cylinder head:
- Turbocharger.
5. Valve rocker covers.
6. Rocker arms and pushrods.
7. Intake manifold.
8. Exhaust manifolds.
9. Cylinder head bolts (13).
10. Cylinder heads (12) and head gaskets (14).

Clean

- Cylinder head and block gasket mating surfaces.
- Threads in cylinder block by using an appropriate tap.

Disassemble

Tool Required:
- J 8101 Valve Guide Cleaner

Important: During disassembly, be sure that the valvetrain components are kept together and identified so that they can be re-installed in their original locations and with the same mating surfaces as when removed.

1. Valve assemblies.
2. Oil gallery and water jacked plugs.
- Threaded plugs.
- Cup plugs, if damaged or leaking.
- Obtain a suitable self-threading screw.
- Drill a hold in the plug.
- Install the self-threading screw.
- Pry out plug.
3. Spark plugs.

Inspect

- Cylinder head gasket (14) and mating surfaces for leaks, corrosion and blow-by. If the gasket has failed, determine the cause:
- Improper installation.
- Loose or warped cylinder head.
- Missing dowel pins.
- Excessive boost pressure.

Clean

Caution: Safety glasses must be worn when using a power wire brush to avoid injury to the eyes.

- Cylinder head bolts (13).
- Cylinder head (12). Remove all varnish, soot, and carbon to the bare metal. Do not use a motorized wire brush on any gasket sealing surfaces.
- Valve guides using J 8101.
- Threaded holes.
- Remains of sealer from plug holes.

Inspect

1. Cylinder head bolts for damaged threads or stretched and damaged heads caused by improper use of tools.

Important: Any bolts that are suspected of damage must be replaced.

2. Cylinder heads for cracks, especially between valve seats and in the exhaust ports.
3. Cylinder head deck for corrosion, sand inclusions and blow holes.
- Do not attempt to weld the cylinder head, replace it.
4. Cylinder head deck, intake and exhaust manifold mating surfaces for flatness. These surfaces may be re-conditioned by parallel grinding. If more than 0.25mm (0.010 inch) must be removed, replace the head.
5. All thread holes for damage. Threads may be re-conditioned with thread inserts.
6. Seating surfaces.
- Water jacket plugs.
7. Valve guides for wear.
- Since the valve guide serves to support and center the valve grinder, it is essential that the valve guide is serviced before reconditioning the valve seats. The valve guide must be cleaned properly before any measuring or servicing takes place. If the valve guide requires reaming, this must be done first.
8. Valve seats for excessive wear and burned spots.
- Valve seats may be re-conditioned by grinding. An oscillating type valve seat grinder is preferred. Follow the grinder manufacturer's instructions. If, after grinding, the new seat is too wide, it may be narrowed by using a 20 degree or 70 degree stone. The 20 degree stone will lower the seat and the 70 degree stone will raise the seat. If the seats are re-conditioned the valves must also be re-conditioned or replaced.

Assemble

1. Oil gallery and cooling jacket plugs. Coat plugs with GM 1050026 sealer or equivalent.
2. Valve assemblies.
3. Spark plugs. Tighten spark plugs to 27 Nm (20 ft. lbs.).

Install or Connect

1. Cylinder head gaskets (14) on cylinder block.
2. Cylinder heads (12).

Notice: When fasteners are removed, always reinstall them at the same location from which they were removed. If a fastener needs to be replaced, use the correct part number fastener for that application. If the correct part number is not available, a fastener of equal size and strength (or stronger) may be used. Fasteners that are not reused, and those requiring thread locking compound will be called out. The correct torque value must be used when installing fasteners that require it. If the above conditions are not followed, parts or system damaged could result.

- Apply thread sealer, GM part number 1052080 or equivalent on cylinder head bolt threads.
3. Cylinder head bolts (13).

Notice: This engine uses special torque to yield head bolts. This design bolt requires a special tightening procedure. Failure to follow the given procedure will cause head gasket failure and possible engine damage.

- Tighten bolts to 47 Nm (35 ft. lbs.) in the sequence shown.

Important: If torque reaches 88 Nm (65 ft. lbs.) at any time in steps 4 and 5, stop at this point. Do not complete the balance of the 90 degree turn.

4. Tighten each bolt 1/4 turn (90 degrees) in sequence.
5. Tighten each bolt an additional 1/4 turn (90 degrees)
6. Exhaust manifolds.
7. Intake manifold.
8. Rocker arms and pushrods.
9. Valve rocker covers.
10. On the right cylinder head:
- Turbocharger.
11. On the left cylinder head:
- Bracket with power steering pump.
- Air conditioning compressor.
- Generator.
12. Serpentine belt.
13. Negative battery cable.