2. Drain the coolant.
3. Remove the air filter.
4. Disconnect the vacuum booster hose.
5. Mark and disconnect the hoses from the intake manifold and from the throttle body or carburetor.
10.8 Crankcase ventilation tubes
6. Disconnect the fuel hoses from the pipes (on injection engines, first decompress, see Ch. 4).
7. Disconnect the recirculation valve vacuum hoses from the intake manifold.
[Information copied from the website: nissanbook]
8. Disconnect the tube from the recirculation valve, as well as the tube from the crankcase ventilation valve (photo).
9. Disconnect the throttle cable.
10. Disconnect the wiring connectors from the carburetor and manifold.
11. Remove the upper radiator hose.
12. Remove the lower thermostat bolt and disconnect the battery ground cable.
13. Disconnect the coolant hose at the bottom of the manifold.
14. Disconnect the hose from the crankcase ventilation valve
15. Unscrew the bolts and remove the intake manifold assembly with the carburetor (or throttle body) and other units.
16. Clean the manifold.
17. Install a new gasket on the manifold. Screw the two lower bolts with washers into the cylinder head, the beveled part of the washers should face away from the engine. Install the manifold and tighten the bolts.
18. Tighten the bolts to the specified torque, from the center to the periphery in a crisscross pattern.
19. The remaining operations are performed in reverse order.
20. Fill the engine with fluid. Warm up the engine and check for leaks. Adjust the idle speed.