Nissan Pick-ups and Pathfinder 1970-1988

Adjustments

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L16, L18 AND L20B ENGINES



See Figures 1 and 2

  1. The valves are adjusted with the engine at normal operating temperature. Oil temperature, and the resultant parts expansion, is much more important than water temperature. Run the engine for at least fifteen minutes to ensure that all the parts have reached their full expansion. After the engine is warmed up, shut it off.
  2.  
  3. Purchase either a new gasket or some silicone gasket seal before remove the cylinder head cover. Note the location of any wires and hoses which may interfere with cover removal, disconnect them and move them aside. Then remove the bolts which hold the cylinder head cover in place and remove the cover.
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  5. Place a wrench on the crankshaft pulley bolt and turn the engine over until the valves for the No. 1 cylinder are closed. When both camshaft lobes are pointing up, the valves are closed. If you have not done this before, it is a good idea to turn the engine over slowly several times and watch the valve action until you have a clear idea of just when the valve is closed.
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  7. Check the clearance of the intake and exhaust valves. You can differentiate between them by lining them up with the tubes of the intake and exhaust manifolds. The correct size feeler gauge should pass between the base circle of the camshaft and the rocker arm with just a slight drag. Be sure the feeler gauge is inserted straight and not on an angle.
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  9. If the valves need adjustment, loosen the locking nut and then adjust the clearance with the adjusting screw. You will probably find it necessary to hold the locking nut while you turn the adjuster. After you have the correct clearance, tighten the locking nut and recheck the clearance. Remember, its better to have them too loose than too tight, especially exhaust valves.
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  11. Repeat this procedure until you have checked and/or adjusted all the valves. Keep in mind that all that is necessary is to have the valves closed and the camshaft lobes pointing up. It is not particularly important what stroke the engine is on.
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  13. Install the cam cover gasket, the cam cover, and any wires and hoses which were removed.
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Fig. Fig. 1: Loosen the locknut and turn the pivot adjuster to adjust the valve clearance-L16, L18 and L20B engines



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Fig. Fig. 2: Checking the valve clearance with a flat feeler gauge-L16, L18 and L20B engines

1981-82 Z22 ENGINES



See Figures 3, 4, 5 and 6

  1. The valves must be adjusted with the engine warm, so start the truck and run the engine until the needle on the temperature gauges reaches the middle of the gauge indicating normal operating temperature. After the engine is warm, shut it off.
  2.  
  3. Purchase either a new gasket or some silicone gasket sealer before removing the cylinder head cover. Counting on the old gasket to be in good shape is a losing proposition; always use new gaskets. Note the location of any wires and hoses which may interfere with cylinder head cover removal, disconnect them and move them to one side. Remove the bolts holding the cover in place and remove the cover. Remember, the engine will be hot, so be careful!
  4.  
  5. Place a wrench on the crankshaft pulley bolt and turn the engine over until the first cam lobe behind the camshaft timing chain sprocket is pointing straight down.
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If you decide to turn the engine by bumping it with the starter, be sure to disconnect the high tension wire from the coil(s) to prevent the engine from accidentally starting and spewing oil all over the engine compartment.


CAUTION
Never attempt to turn the engine by using a wrench on the camshaft sprocket bolt; there is a one to two turning ratio between the camshaft and the crankshaft which will put a tremendous strain on the timing chain.

  1. See the illustration marked FIRST, and check valves (1), (4), (6) and (7) using a 0.012 in. (0.3mm) flat bladed feeler gauge. The feeler gauge should pass between the valve stem end and the rocker arm screw with a very slight drag. Insert the feeler gauge straight, not at an angle.
  2.  
  3. If the clearance is not within specified value, loosen the rocker arm locknut and turn the rocker arm screw to obtain the proper clearance. After correct clearance is obtained, tighten the locknut.
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  5. Turn the engine over so that the first cam lobe behind the camshaft timing chain sprocket is pointing straight up and check the valves marked (2), (3), (5) and (8) in the SECOND illustration. They, too, should have a clearance of 0.012 in. (0.3mm). Adjust as necessary.
  6.  
  7. Install the cylinder head cover gasket, the cover itself and any wires and hoses which were removed.
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Fig. Fig. 3: The proper size feeler gauge should pass with a slight drag-1981-82 Z22 engines



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Fig. Fig. 4: Loosen the locknut and turn the adjusting screw to adjust the valve clearance-1981-82 Z22 engines



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Fig. Fig. 5: With the camshaft lobe pointing down, adjust these valves FIRST-1981-82 Z22 engines



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Fig. Fig. 6: With the camshaft lobe pointing down, adjust these valves SECOND-1981-82 Z22 engines

Z20, Z22 (EXCEPT 1981-82), Z24, Z24i GASOLINE ENGINES, AND SD22, SD25 DIESEL ENGINES

See Figures 7, 8, 9, 10, 11, 12 and 13

  1. The valves must be adjusted with the engine warm, so start the truck and run the engine until the needle on the temperature gauge reaches the middle of the gauge indicating normal operating temperature. After the engine is warm, shut it off.
  2.  
  3. Purchase either a new gasket or some silicone gasket sealer before removing the cylinder head cover. Counting on the old gasket to be in good shape is a losing proposition; always use new gaskets. Note the location of any wires and hoses which may interfere with cylinder head cover removal, disconnect them and move them to one side. Remove the bolts holding the cover in place and remove the cover. Remember, the engine will be hot, so be careful!
  4.  
  5. Rotate the crankshaft until the timing marks indicate that the No. 1 piston is at TDC of the compression stroke. If you're not sure of which stroke you're on, remove the No. 1 spark plug and hold your thumb over the hole. Pressure will be felt as the piston starts up on the compression stroke.
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  7. See the proper illustration marked FIRST, and check valves (1), (2), (4) and (6)-gasoline engines, or (1), (2), (3) and (5)-diesel engines using a flat bladed feeler gauge. The feeler gauge should pass between the valve stem end and the rocker arm screw with a very slight drag. Insert the feeler gauge straight, not at an angle.
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  9. If the clearance is not within specified value, loosen the rocker arm locknut and turn the rocker arm screw to obtain the proper clearance. After correct clearance is obtained, tighten the locknut.
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  11. Rotate the crankshaft until the timing marks indicate that the No. 4 piston is at TDC of the compression stroke. If you're not sure of which stroke you're on, remove the No. 4 spark plug and hold your thumb over the hole. Pressure will be felt as the piston starts up on the compression stroke.
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  13. See the appropriate illustration marked SECOND, and check valves (3), (5), (7) and (8)-gasoline engines, or (4), (6), (7) and (8)-diesel engines. Check and adjust valve clearance as detailed in Steps 4-5.
  14.  
  15. Install the cylinder head cover gasket, the cover itself and any wires and hoses which were removed.
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Fig. Fig. 7: Checking the valve clearance with a flat feeler gauge (a slight drag should be felt)-Z20, Z22 (except 1981-82), Z24 and Z24i engines



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Fig. Fig. 8: Loosen the locknut and turn the adjusting screw to adjust the valve clearance-Z20, Z22 (except 1981-82), Z24 and Z24i engines



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Fig. Fig. 9: Checking the valve clearance with a flat feeler gauge-SD22 and SD25 engines



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Fig. Fig. 10: Loosen the locknut and turn the adjusting screw to adjust the valve clearance-SD22 and SD25 engines



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Fig. Fig. 11: With the No. 1 piston at TDC, adjust the top set of valves FIRST; with the No. 4 piston at TDC, adjust the bottom set of valves SECOND-Z20, Z22 (except 1981-82), Z24 and Z24i engines



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Fig. Fig. 12: With the No. 1 piston at TDC, adjust these valves FIRST-SD22 and SD25 engines



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Fig. Fig. 13: With the No. 4 piston at TDC, adjust these valves SECOND-SD22 and SD25 engines

VG30i ENGINES

These models utilize hydraulic valve lifters. Periodic adjustment is neither necessary or possible.

 
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