Removal
1. Remove the cylinder head covers (see section Removal and installation cylinder head covers).
2. Moving from the ends to the middle, loosen the rocker arm axle mounting bolts in two or three steps.
Caution! Some valves will remain open when the rocker arm axle fasteners are loosened, which will expose the axles to the forces developed by the valve springs, and abruptly releasing the fastening bolts may result in deformation of the components.
3. Rocker arm assemblies should be clearly marked before removal from the engine.
4. Unscrew the loosened mounting bolts and remove the axle assemblies with rocker arms from the head one by one. Place the removed assemblies on the workbench, arranging them in the same way as they were installed in the engine. When assembling, all axles must be installed strictly in their original places in their cylinder heads. Note that axles with deep recesses are installed from the intake manifold side, and those with shallow recesses are installed from the exhaust manifold side.
Examination
1. After removing the rocker arm assemblies, it is a good idea to disassemble them in order to examine the components in more detail. Clean the parts thoroughly and inspect them for signs of wear and damage. Assess the condition of the rocker arm surfaces that contact the camshaft. Check for scoring and signs of excessive wear on the rocker arm seating surfaces on the axles, as well as the walls of the rocker arm mounting holes themselves. Defective components must be replaced.
2. Measure the outside diameters of the rocker arm journals. Record the measurements and compare them with the Specifications.
3. Measure the inside diameters of the rocker arm mounting holes. Also compare the results with the requirements of the Specifications.
4. By subtracting the results of the first measurements from the results of the second, determine the value of the rocker arm mounting clearances on the axles. Compare the calculation results with the requirements of the Specifications. If necessary, replace excessively worn components.
[The text is published on the website: NissanBook]
Installation
Installation is performed in the reverse order. Tightening the rocker arm axle mounting bolts with the required force should be performed in several stages in the direction from the ends of the assemblies to their centers.