Nissan Z - ZX 1970-1988 Repair Guide

Cylinder Head

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REMOVAL



Except VG Engines

See Figures 1, 2, 3 and 4

  1. Crank the engine until the No. 1 cylinder is at TDC of the compression stroke.
  2.  
  3. Disconnect the negative battery cable, drain the coolant, then remove the air cleaner and the attending hoses.
  4.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.



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Fig. Fig. 1: Tag all connections before removing the fuel injection harness-1975-83 models



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Fig. Fig. 2: A wedge like this can be helpful in supporting the timing chain



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Fig. Fig. 3: Support the timing chain with the wedge



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Fig. Fig. 4: Note the placement and length of the bolts

  1. Remove the upper radiator hose, the heater hoses, the thermostat housing (coolant outlet elbow) and the thermostat. Label the electrical connectors.
  2.  

When removing the thermostat housing, the thermo-time switch (fuel injected models), the temperature switch(es) and the vacuum switching valve can be removed as an assembly.

  1. If equipped with power steering, unbolt the pump and move it aside; DO NOT disconnect the lines. If necessary, remove the alternator, on some models.
  2.  
  3. Label and disconnect the spark plug wires, then remove the spark plugs.
  4.  
  5. Disconnect the fuel line(s).
  6.  

On fuel injected models, be sure to relieve fuel line pressure as outlined in fuel filter replacement in General Information & Maintenance ; label and disconnect all of the electrical wiring to the fuel injection.

  1. On 1970-74 models, disconnect the water, air, vacuum and fuel hoses or lines from the carburetors, then remove the fuel pump.
  2.  
  3. On fuel injected models, the fuel injection assembly will be removed intact with the intake manifold. Disconnect the hose from the rocker cover which runs to the throttle chamber. Remove the coolant pipe/fuel pipe retaining bolt from the cylinder head.
  4.  
  5. If equipped, disconnect and remove the EGR control tube and the EGR valve.
  6.  
  7. Disconnect the coolant piping and the exhaust gas inlet tube from the intake manifold.
  8.  
  9. Most 1979 and later models have an auxiliary coolant fan on the right-side of the engine, with ducting which runs over the rocker cover to the intake manifold. Remove this ducting, if equipped.
  10.  
  11. Remove the rocker arm cover.
  12.  
  13. Remove the air conditioner fast idle mechanism and bracket, if equipped.
  14.  
  15. Remove the coolant tube from the balance tube of the manifold, then remove the balance tube, if equipped.
  16.  
  17. Remove the exhaust heat shield plate, then disconnect the exhaust pipe from the exhaust manifold or from the turbocharger exhaust outlet (if equipped). Disconnect the EGR tube from the exhaust manifold.
  18.  
  19. If equipped with air injection, remove the air pump hose from the air injection gallery pipe.
  20.  
  21. Remove the exhaust manifold and the intake manifold.
  22.  
  23. Disconnect the cylinder head temperature sender.
  24.  
  25. Using paint or chalk, mark the relationship of the camshaft sprocket to the timing chain with paint or chalk.
  26.  

Once the timing chain and camshaft sprocket have been marked, it will not be necessary to locate the factory timing marks. Before removing the camshaft sprocket, it will be necessary to wedge the chain in place so that it will not fall down into the front cover. The factory procedure is to wedge the timing chain in place with the wooden wedge shown here. The problem with this is that it may allow the chain tensioner to move out far enough to cock itself against the chain. If this happens, the chain may not go back over the sprocket when it is installed; it will be necessary to remove the front cover and push the tensioner back.

  1. After installing the wedge, unbolt and remove the camshaft sprocket.
  2.  
  3. If equipped, remove the valve train oil gallery pipe.
  4.  

The cylinder head bolts are of two different lengths, be sure to install them in their correct positions.

  1. Using a 10mm Allen wrench, loosen and remove the cylinder head bolts in the reverse order of the tightening sequence to prevent head warpage. Keep the bolts in order, for they are of different lengths. Lift the cylinder head from the engine; this may require an assistant.
  2.  

VG Engines

See Figures 5, 6, 7, 8 and 9

This procedure includes the camshaft, intake manifold, exhaust manifold and rocker arm shaft removal procedures.

  1. Refer to the Engine removal and installation procedures in this section, then remove the engine and support it on an engine stand.
  2.  
  3. Remove the spark plugs and turn the crankshaft (using a wrench on the crankshaft pulley) until the No. 1 cylinder is at TDC of the compression stroke.
  4.  
  5. Remove the crankshaft pulley bolt, the crankshaft pulley and the timing belt (upper and lower) covers. Loosen the timing belt tensioner pulley, then remove the timing belt (mark the direction of rotation).
  6.  



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Fig. Fig. 5: Intake manifold collector bolt removal sequence



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Fig. Fig. 6: Intake manifold bolt removal order



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Fig. Fig. 7: Cylinder head bolt removal sequence

Before removing the timing belt, be sure to mark the belt with the relationship of the camshaft sprockets and the crankshaft sprocket.

  1. Remove the camshaft sprocket bolts, the sprockets and the rear timing belt cover.
  2.  
  3. Remove the coolant draincocks from the cylinder block and drain the coolant from the block.
  4.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.



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Fig. Fig. 8: Loosen and remove the cylinder head bolts, referring to the diagram for the correct order



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Fig. Fig. 9: Carefully lift the cylinder head out of the engine compartment

  1. Remove the collector cover and collector.
  2.  
  3. Remove the intake manifold with fuel tube assembly.
  4.  
  5. Remove the power steering pump bracket.
  6.  
  7. Remove the exhaust manifold stay, then disconnect the exhaust manifold connecting tube.
  8.  
  9. Remove the compressor, the compressor bracket and the valve covers.
  10.  
  11. Remove the cylinder head with the exhaust manifold.
  12.  

CLEANING AND INSPECTION



See Figures 10, 11 and 12

Using a putty knife, clean the gasket surface of the cylinder head. Using a wire brush, clean the carbon from the piston head depressions and the valves in the cylinder head.



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Fig. Fig. 10: Use a putty knife or gasket scraper to remove the bulk of the old gasket material



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Fig. Fig. 11: An electric drill with a wire wheel can speed up the removal of any remaining gasket material



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Fig. Fig. 12: Checks should be made straight across the head and at both diagonals

Inspect the cylinder head for cracks and other flaws. Using a straightedge and a feeler gauge, measure the warpage of the cylinder head-to-block mating surface. If warpage exceeds 0.1mm or there is other damage, repair or replace the head, as required.

RESURFACING



If the cylinder head warpage is significant, requiring the head to be machined, submit it to a reputable automotive machine shop.

Before resurfacing, the cylinder head must be disassembled. Refer to the Camshaft removal and installation procedures in this section, and disassemble the cylinder head.

INSTALLATION



Except VG Engines

See Figure 13

  1. With the crankshaft turned so that the No. 1 cylinder is at TDC of the compression stroke (if not already done so), make sure that the camshaft sprocket timing mark and the oblong groove in the camshaft retaining plate are aligned.
  2.  
  3. Place the cylinder head in position on the block, being careful not to allow any of the valves to contact any of the pistons.
  4.  



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Fig. Fig. 13: Head bolt torquing sequence-1970-83 models

DO NOT rotate the crankshaft or camshaft separately because of possible damage which might occur to the valves.

  1. Temporarily install and tighten the two center (right and left) cylinder head bolts to 14 ft. lbs. (18 Nm).
  2.  
  3. Install the camshaft sprocket together with the timing chain onto the camshaft. Make sure that the marks made earlier, line up. If the chain will not stretch over the sprocket, the problem lies in the tensioner. Refer to the Timing Chain removal and installation procedure for the timing procedure, if necessary.
  4.  
  5. Install the cylinder head bolts. Note that two lengths are used. Tighten the bolts in sequence.
  6.  
  7. 1970-71 models :
    1. Tighten the bolts to 33 ft. lbs. (43 Nm)
    2.  
    3. Tighten the bolts to 47 ft. lbs. (61 Nm)
    4.  

  8.  
  9. 1972 models :
    1. Tighten the bolts to 47 ft. lbs. (61 Nm)
    2.  
    3. Tighten the bolts to 55 ft. lbs. (71 Nm)
    4.  

  10.  
  11. 1973-83 models :
    1. Tighten the bolts to 30 ft. lbs. (39 Nm)
    2.  
    3. Tighten the bolts to 44 ft. lbs. (57 Nm)
    4.  
    5. Tighten the bolts to 54-61 ft. lbs. (70-79 Nm)
    6.  

  12.  
  13. To complete the installation, reverse the removal procedures. Adjust the valves to a preliminary COLD clearance of 0.2mm for the intake and 0.25mm for the exhaust. Operate the engine until it is at normal operating temperature, retighten the head bolts (loosen them slightly and retighten to the final torque figure) and adjust the valves to the HOT clearance specifications.
  14.  

VG Engine

See Figures 14, 15, 16, 17, 18, 19 and 20

  1. Make sure the No. 1 cylinder is set at TDC on its compression stroke as follows:
    1. Align the crankshaft timing sprocket mark with the mark on the oil pump housing.
    2.  
    3. The knock pin in the front end of the camshaft should be facing upward.
    4.  

  2.  

DO NOT rotate the crankshaft or the camshaft separately because the valves will hit piston head.

  1. Using a new cylinder head gasket, install the cylinder head.
  2.  



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Fig. Fig. 14: Align the timing mark on the crankshaft pulley with the mark on the oil pump housing



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Fig. Fig. 15: Make sure the knockpin on the camshaft(s) faces upward



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Fig. Fig. 16: Cylinder head torque sequence



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Fig. Fig. 17: When tightening the cylinder head bolts, use a torque wrench



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Fig. Fig. 18: Install the camshaft pulley



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Fig. Fig. 19: Camshaft alignment marks



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Fig. Fig. 20: Intake manifold torque sequence

Before installing the cylinder head bolts, apply oil to the thread and the seat portions.

  1. Tighten the cylinder head bolts in five steps, using the numerical sequence, by performing the following procedures:
    1. Tighten the bolts to 22 ft. lbs. (29 Nm).
    2.  
    3. Tighten the bolts to 43 ft. lbs. (59 Nm).
    4.  
    5. Loosen the bolts completely.
    6.  
    7. Tighten the bolts to 22 ft. lbs. (29 Nm).
    8.  
    9. Tighten the bolts to 40-47 ft. lbs. (54-64 Nm) or if using an angle wrench, turn the bolts 60-65° clockwise.
    10.  

  2.  

Bolt Nos. 4, 5, 12, and 13 in the sequence illustration are longer than the others.

  1. Tighten the rear timing cover.
  2.  
  3. Install the camshaft pulley and tighten the bolt to 58-65 ft. lbs. (75-84 Nm).
  4.  

The right-hand and the left-hand camshaft pulleys are different parts. Install them in the correct positions. The right-hand pulley has an R3 identification mark and the left-hand has an L3.

  1. Install the timing belt and adjust the tension.
  2.  
  3. Install the front upper and lower belt covers.
  4.  
  5. Install the valve lifters and lifter guide. Hold all valve lifters with a wire as was done during disassembly and install to their original position.
  6.  
  7. Install the rocker shafts with the rocker arms and tighten the rocker shaft bolts to 13-16 ft. lbs. (17-21 Nm), in two or three stages.
  8.  
  9. Install the rocker cover.
  10.  
  11. Install the intake manifold and fuel tube; tighten the bolts in two or three stages, in numerical order:
  12.  
  13. Nuts :
    1. Tighten the nuts to 2.2-3.6 ft. lbs. (3-5 Nm).
    2.  
    3. Tighten the nuts to 17-20 ft. lbs. (24-27 Nm).
    4.  

  14.  
  15. Bolts :
    1. Tighten the bolts to 2.2-3.6 ft. lbs. (3-5 Nm).
    2.  
    3. Tighten the bolts to 12-14 ft. lbs. (16-20 Nm).
    4.  

  16.  
  17. Install the exhaust manifolds and connecting tube, then tighten the fasteners in sequence to 13-16 ft. lbs. (17-21 Nm). Tighten the connector tube to 16-20 ft. lbs. (21-26 Nm).
  18.  
  19. To complete the installation, reverse the removal procedures.
  20.  

 
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