Nissan Z - ZX 1970-1988 Repair Guide

Pistons and Connecting Rods

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11



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Fig. Fig. 1: Cylinder bore ridge

  1. Refer the Engine removal and installation procedures in this section, then remove the engine and secure it to a workstand.
  2.  
  3. Remove the cylinder head and the oil pan.
  4.  
  5. Using a ridge reamer tool, remove any carbon buildup from the cylinder wall at the top end of the piston travel.
  6.  



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Fig. Fig. 2: Place rubber hoses over the connecting rod studs to protect the crankshaft and cylinder bores from damage



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Fig. Fig. 3: The piston and connecting rod can be tapped out using a hammer and piece of wood



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Fig. Fig. 4: An alternative method is to push out the piston and connecting rod from the bore



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Fig. Fig. 5: Piston ring arrangement-1970-78 models



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Fig. Fig. 6: Piston ring arrangement-1979-83 models



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Fig. Fig. 7: Piston ring arrangement-1984-88 models



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Fig. Fig. 8: Side view of piston ring arrangement-1984-88 models



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Fig. Fig. 9: Piston and connecting rod identification marks-1970-83 models



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Fig. Fig. 10: Piston and connecting rod identification marks-1984-88 models



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Fig. Fig. 11: Installing the piston into the block using a ring compressor and the handle of a hammer

  1. Position the piston to be removed at the bottom of its stroke so that the connecting rod bearing cap can be reached easily from under the engine.
  2.  
  3. Unscrew the connecting rod bearing cap, then remove the cap and lower half of the bearing.
  4.  

It is advisable to number the pistons, connecting rods and bearing caps in some manner so that they can be reinstalled in the same cylinder, facing the same direction, from which they are removed.

  1. Push the piston/connecting rod assembly up and out of the cylinder block with a length of wood. Use care not to scratch the cylinder wall with the connecting rod or the wooden tool.
  2.  
  3. Keep all of the components from each cylinder together and install them in the cylinder from which they were removed.
  4.  
  5. Coat the bearing face of the connecting rod and the outer face of the pistons with engine oil.
  6.  
  7. When installing the piston, align them according to the following procedure:
    1. On the 1970-78 engines, turn the top compression ring to bring its gap to about the 1 o'clock position. Set the remaining rings so that their gaps are positioned 180° apart around the piston. The oil ring gap will be directly under the top compression ring gap.
    2.  
    3. On 1979 and later engines, set the top ring gap at the 1 o'clock position. Position the second ring gap 180° opposite the top ring gap. The top oil ring rail gap should then be placed under the top ring gap, the expander ring should be at the 3 o'clock position and the bottom oil ring rail gap should be under the second ring gap. See the illustration for details.
    4.  

  8.  
  9. Turn the crankshaft until the rod journal of the particular cylinder you are working on is brought to TDC.
  10.  
  11. With the piston and rings clamped in a ring compressor, the notched mark on the head of the piston toward the front of the engine and the oil hole side of the connecting rod toward the right-side (except VG) or facing the crankshaft (VG) of the engine, push the piston and connecting rod assembly into the cylinder bore until the big bearing end of the connecting rod contacts and is seated on the rod journal of the crankshaft. Use care not to scratch the cylinder wall with the connecting rod.
  12.  
  13. Push down farther on the piston and turn the crankshaft while the connecting rod rides around on the crankshaft rod journal. Turn the crankshaft until the crankshaft rod journal is at Bottom Dead Center (BDC).
  14.  
  15. Align the mark on the connecting rod bearing cap with that on the connecting rod and tighten the bearing cap bolts to the specified torque.
  16.  
  17. Install the piston/connecting rod assemblies in the manner outlined above, use the Plastigage® method of checking the connecting rod-to-crankshaft bearing tolerances.
  18.  
  19. To complete the installation, reverse the removal procedures.
  20.  

CLEANING AND INSPECTION



Pistons

See Figures 12, 13, 14, 15 and 16

For the following operations, the piston should be disassembled from the connecting rod.

  1. Using a wooden scraper, clean the carbon from the outer surface of the pistons.
  2.  
  3. Using a piston ring land area cleaning tool or a piece of an old piston ring, scrape the carbon from the piston's ring land area.
  4.  



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Fig. Fig. 12: Remove the old piston ring with a ring expander tool



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Fig. Fig. 13: Clean the piston groove using a piston groove cleaner ...



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Fig. Fig. 14: ... or a piece of an old piston ring; be careful of sharp edges on the ring



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Fig. Fig. 15: Measuring the piston's outer diameter



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Fig. Fig. 16: Check the ring-to-ring groove clearance


WARNING
When cleaning the piston's ring land area, be careful not to remove any metal from the piston.

  1. Flush the piston in solvent to remove any oil and loose debris.
  2.  
  3. Inspect the piston for damage or wear (especially at the skirt area) and make sure that the piston pin slides easily into the piston bore.
  4.  
  5. Using the new piston rings and a feeler gauge, check the piston ring land areas for the ring side clearance, it must not be greater than 0.1mm.
  6.  

Connecting Rods
  1. Disassemble the connecting rod from the piston.
  2.  
  3. Clean the connecting rod in solvent to remove the oil and loose debris.
  4.  
  5. Using an internal dial micrometer, check the diameter of the piston pin and the crankshaft bore.
  6.  
  7. Using the Magnaflux® process, inspect the connecting rod for damage, stress cracks or wear; replace it (if necessary).
  8.  

Engine Block

See Figures 17, 18, 19 and 20

  1. Using solvent an a clean rag, wipe the cylinder bores clean of the oil and loose debris.
  2.  
  3. Using an internal dial micrometer or telescoping gauges and a micrometer, measure the cylinder bore at the top, middle and bottom. When measuring the cylinder bore, be sure to make a measurement at 90° to the initial one.
  4.  



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Fig. Fig. 17: Remove cylinder glazing using a flexible hone



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Fig. Fig. 18: Use a telescopic gauge to measure the cylinder bore diameter



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Fig. Fig. 19: A properly cross-hatched cylinder bore



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Fig. Fig. 20: Check the piston ring end-gap

  1. Using a honing tool and some clean engine oil, hone the cylinder walls (to break the glaze). The cylinder bore MUST BE the same diameter throughout the length of the bore.
  2.  
  3. Place the new piston rings into the cylinder bore, then using a feeler gauge, check the ring end-gap.
  4.  

PISTON PIN REPLACEMENT



See Figure 21

The piston pin is pressed into the connecting rod.

  1. Using an arbor press, a drift and the supporting tool No. ST13030001 (except VG) or KV10110300 (VG), press the piston pin from the piston assembly.
  2.  



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Fig. Fig. 21: Pressing out the piston pin

  1. Clean and inspect the piston and the connecting rod bores.
  2.  
  3. Apply clean engine oil to the parts.
  4.  
  5. To install the piston pin, press the pin into the piston assembly until the pin is flush with the piston.
  6.  

PISTON RING REPLACEMENT



See Figures 22, 23 and 24

  1. Using a ring expander tool, remove the rings from the piston.
  2.  
  3. Clean and inspect the piston's ring land area for damage or wear, replace the piston (if necessary).
  4.  

The contact edges of rings used on the turbocharged engines are not as sharply machined as those used on the non-turbocharged engines.

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Fig. Fig. 22: Remove the ring with a ring expander



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Fig. Fig. 23: Cleaning the groove



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Fig. Fig. 24: Most rings are marked to show which side faces up

  1. Place the new rings into the cylinder bore and check them with a feeler gauge to make sure that the end-gap is correct; the maximum end-gap is 1.0mm.
  2.  

To identify the top of the rings, look for a marking on the top or a beveled edge.


WARNING
When using the ring expander, be careful not to break the rings.

  1. Using new rings and a ring expander tool, install the new rings onto the piston; start with the bottom ring and work toward the top compression ring.
  2.  

ROD BEARING REPLACEMENT



The connecting rod-to-crankshaft bearings are two piece, they are held into the rod and the rod bearing cap by tabs. When replacing the bearings, be sure that the oil hole in the rod aligns with the oil hole in the bearing.

 
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