Cylinder Head

CLEAN CYLINDER HEAD
1. Remove gasket material using a suitable gasket scraper, remove all the gasket material from the cylinder block surface.

NOTE: Be careful not to scratch the cylinder block contact surface.

2. Clean combustion chambers using a suitable wire brush, remove all the carbon from the combustion chambers.

NOTE: Be careful not to scratch the cylinder block contact surface.

3. Clean valve guide bushings using a valve guide bushing brush and solvent.

4. Clean cylinder head using a soft brush and solvent.

INSPECT CYLINDER HEAD
1. Inspect for flatness Using precision straight edge and feeler gauge.
- Measure the surfaces contacting the cylinder block, intake and exhaust manifolds for warpage.
Maximum warpage: 0.10 mm (0.0039 inch).
- If warpage is greater than maximum, replace the cylinder head.

2. Inspect for cracks.
- Using a suitable dye penetrant, check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks.
- If cracked, replace the cylinder head.

INSPECT VALVE LIFTER BORES
1. Using a caliper gauge, measure the lifter bore diameter of the cylinder head.
Lifter bore diameter: 31.000-31.016 mm (1.2205-1.2211 inch).
2. Using a micrometer, measure the lifter diameter.
Lifter diameter: 30.966-30.976 mm (1.2191 1.2195 inch).
3. Subtract the lifter diameter measurement from the lifter bore diameter measurement.
Standard oil clearance: 0.024-0.050 mm (0.0009-0.0020 inch).
Maximum oil clearance: 0.07 mm (0.0028 inch).
4. If the oil clearance is greater than maximum, replace the lifter. If necessary, replace the cylinder head.

INSPECT CAMSHAFTS BEARINGS
1. Check the bearings for flaking and scoring.

NOTE: If the bearings are damaged, replace the bearing cap and cylinder head as a set.

2. Inspect camshaft journal oil clearance as follows:
(a) Clean the bearing caps and camshaft journal.
(b) Place the camshafts on the cylinder head.

(e) Place the camshaft on the cylinder head with the cam lobe facing up as shown.

(f) Place the No. 3 and No. 7 bearing caps in their proper location.
(g) Apply a light coat of engine oil on the threads and under the heads of the bearing cap bolts.

(h) Hand tighten these bearing cap bolts uniformly and alternately, in several passes, until the bearing caps are snug with the cylinder head.

(i) Install the No. 1, No. 2, No. 4, No. 5 and No. 6 bearing caps in their proper locations.
(j) Apply a light coat of engine oil on the threads and under the heads of the bearing cap bolts.

(k) Install and uniformly tighten the 14 bearing cap bolt on one side, in several passes, in the sequence shown to 20 Nm (14 ft. lbs.).

NOTE: Do not turn the camshaft.

(l) Remove camshafts as follows:

- Uniformly loosen and remove the four No. 1 bearing cap bolts.
- Using a screwdriver, pry out the two No. 1 camshaft bearing caps and oil seals.

NOTE: Be careful not to damage the cap. Tape the screwdriver tip.

- Uniformly loosen and remove the 12 bearing cap bolts, in several passes, in the sequence shown.
- Remove the 6 bearing caps and camshaft. Remove the intake and exhaust camshafts.

(m) Measure the Plastigage at its widest point.
Standard oil clearance: 0.035-0.072 mm (0.0014-0.0028 inch).
Maximum oil clearance: 0.10 mm (0.0039 inch).

NOTE:
- If the oil clearance is greater than maximum, refer to camshaft inspection.
- If the camshaft is to specification, replace the bearing caps and cylinder head as a set.

(n) Completely remove the Plastigage.
3. Inspect camshaft thrust clearance as follows:
(a) Install the camshafts as outlined above.

(b) Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.
Standard thrust clearance: 0.080-0.190 mm (0.0031-0.0075 inch).
Maximum thrust clearance: 0.30 mm (0.0118 inch).

NOTE:
^ If the thrust clearance is greater than maximum, refer to camshaft inspection.
- If the camshaft is to specification, replace the bearing caps and cylinder head as a set.

(c) Remove camshafts as outlined above.