Cylinder Head Assembly: Service and Repair

REMOVAL - CYLINDER HEAD(S)





The aluminum alloy cylinder head shown in (Fig. 22) is held in place by 12, 1/2, inch bolts and 8, 1/4 inch bolts. The spark plugs are located in the peak of the combustion chamber between the valves.
1. Disconnect the battery.
2. Drain the cooling system.
3. Remove the intake manifold.
4. Disconnect the coil wires, coolant temperature sensor, and heater hoses.
5. Remove the closed ventilation system and cylinder head covers.
6. Remove the coolant tubes from engine.
7. Remove the exhaust manifold heat shields.
8. Remove the exhaust manifold(s) and gasket(s).
9. Remove the rocker arm and pedestal assemblies.
10. Remove push rods.

NOTE: Identify each component to insure installation in original locations.





11. Remove the 12 head bolts and 8 valley seal bolts from cylinder head(s) (Fig. 23).
12. Remove cylinder head(s) and gasket(s).

INSPECTION
1. Before cleaning, check for leaks, damage and cracks.
2. Clean cylinder head and oil passages.





3. Check cylinder head for flatness (Fig. 24).
4. Inspect all surfaces with a straightedge if there is any reason to suspect leakage. If out-of-flatness exceeds 0.019 mm (0.00075 inch) times the span length in inches in any direction, either replace head or lightly machine the head surface. As an example, if a 12.0 inch span is 1.0 mm (0.004 inch) out-of-flat, allowable is 12 x 0.019 mm (0.00075 inch) equals 0.22 mm (0.009 inch). This amount of out-of-flat is acceptable. *Maximum of 0.2 mm (0.008 inch) for grinding is permitted.

CAUTION: This is a combined total dimension of stock removal from cylinder head surface.

INSTALLATION - CYLINDER HEAD(S)
1. Clean all surfaces of cylinder block and cylinder heads.

CAUTION: Remove all gasket material from cylinder head and block using a plastic scraper only. DO NOT use a metal scraper, as damage to sealing surface may occur.

NOTE: A multi-layer steel head gasket is used.





2. Install new gasket(s) on the cylinder block (Fig. 25).

CAUTION: Cylinder head bolts are coated, DO NOT oil.





3. Install cylinder head(s). Tighten cylinder head bolts 1-12 in the sequence shown, using a two step torque sequence:
a. First to 47 Nm (35 ft. lbs.).
b. Second to 122 Nm (90 ft. lbs.).
4. After head bolts 1-12 have been tightened to specifications, tighten valley bolts A-H in sequence shown in (Fig. 26) to 11 Nm (95 in. lbs.).
5. Inspect the push rods. Replace worn or bent push rods as necessary.
6. Install the push rods, rocker arms, and pedestal assemblies into position. Tighten bolts to 41 Nm (30 ft. lbs.).





7. Place the new cylinder head cover gasket(s) in position and install the cylinder head covers. Tighten bolts in sequence shown in (Fig. 27) to 11 Nm (95 in. lbs.).

INTAKE MANIFOLD SEALING
The intake manifold gaskets are a one-piece fiber gasket with molded silicone beads applied from the manufacturer.
1. Clean all surfaces of the intake manifold and cylinder heads.





2. Carefully install intake manifold gaskets using the plastic alignment pins (Fig. 28).





3. Install the intake manifold. Install and tighten the bolts initially to 1 Nm (10 in. lbs.). Then tighten the bolts to 11 Nm (95 in. lbs.) in sequence shown in (Fig. 29). After the intake manifold is in place, refer to intake manifold installation.
4. Install the exhaust manifold gaskets.
5. Install the exhaust manifold. The lower center and outer bolts must be installed first to ensure proper alignment of the exhaust manifolds. Tighten bolts to 23 Nm (200 in. lbs.). Install the stud bolts in the upper 5 positions of the manifold.
6. Install the heat shields on exhaust manifolds. Tighten all attaching nuts to 6 Nm (50 in. lbs.).
7. Adjust the spark plug gap and install spark plugs.
8. Fill the cooling system.