Cylinder Head Assembly

1. Discard old oil seal and install new one.
2. Apply coat of engine oil to sealing lips of oil seal and frictional surfaces of moving parts.
3. Install valve components, noting the following:
a. Before installing valve oil seal, install inner valve spring seat.
b. Install outer valve spring with its narrow pitch side toward cylinder head side.
4. Install rocker shaft bracket, valve rocker and spring on valve rocker shaft, noting the following:

Fig. 9 Rocker shaft identification:

a. Intake rocker shaft has identification mark (slit on front surface), but exhaust rocker shaft does not, Fig. 9.
b. Rocker shafts should be assembled so that punched marks on front surfaces face up.
c. On Pathfinder and Pickup, Nos. 1 and 3 cylinder's intake and exhaust valve rockers are same parts and provide identification mark ``1'' and Nos. 2 and 4 cylinder's intake and exhaust valve rockers are same parts and provide identification mark ``2.''
d. On Van, Nos. 2 and 4 cylinder's intake and exhaust valve rockers are same parts and provide identification mark ``2-4.''

Fig. 10 Rocker shaft assembly installation:

e. Be careful not to miss original position of rocker shaft brackets. On Pathfinder and Pickup, alphabetical identification marks are provided on each bracket and cylinder head, Fig. 10.
f. To prevent rocker shaft brackets from slipping out of rocker shafts, insert bracket bolts into bolt holes of Nos. 1 and 5 rocker shaft bracket.
5. Mount camshaft onto cylinder head, placing knock pin at front end to top position. Apply engine oil to camshaft when mounting onto cylinder head.
6. Mount valve rocker shaft assembly on cylinder head by accommodating to knock pin of head, then torque to 11-18 ft. lbs., noting the following:
a. Tighten bolts gradually, in two or three steps, working outwardly from center bracket.
b. When tightening bolts, provide adequate clearance under cylinder head.