Nissan Z - ZX 1970-1988 Repair Guide

Crankshaft and Main Bearings

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REMOVAL & INSTALLATION



Except VG Engines

See Figures 1, 2, 3, 4, 5 and 6

  1. Refer to the Engine removal/installation and the Timing Belt/Chain and Tensioner removal/installation procedures in this section. Remove the engine with the transmission from the vehicle, and the timing chain from the engine.
  2.  
  3. Separate the transmission from the engine.
  4.  

If removing an automatic transmission from the engine, be sure to remove the torque converter-to-drive plate bolts, first.

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Fig. Fig. 1: Some connecting rods and caps are marked for easier alignment



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Fig. Fig. 2: If the connecting rod and cap are not marked, scribe an alignment mark on them



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Fig. Fig. 3: Place rubber hoses over the studs/bolts to prevent possible damage



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Fig. Fig. 4: Tapping out the connecting rod from the cylinder bore



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Fig. Fig. 5: Main bearing components-1970-83 models



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Fig. Fig. 6: Bearing cap torque sequence-1970-83 models

  1. Remove the clutch assembly from the flywheel (manual transmission) or the torque converter from the drive plate (automatic transmission).
  2.  
  3. Remove the flywheel or the drive plate from the crankshaft, then secure the engine to a work stand.
  4.  
  5. If not having done so, drain the crankcase and remove the oil pan.
  6.  


CAUTION
The EPA warns that prolonged contact with used engine oil may cause a number of skin disorders, including cancer! You should make every effort to minimize your exposure to used engine oil. Protective gloves should be worn when changing the oil. Wash your hands and any other exposed skin areas as soon as possible after exposure to used engine oil. Soap and water, or waterless hand cleaner should be used.

  1. Remove the connecting rod bearing cap bolts and the bearing caps, then push the connecting rods away from the crankshaft.
  2.  

The connecting rod bearing caps are numbered, be sure to keep the parts in order for installation purposes. Be sure to slip short pieces of hose over the connecting rod studs, to prevent damaging the crankshaft bearing surfaces.

  1. Remove the main bearing cap bolts, then using the special tool No. KV101041S0, remove the main bearing caps. Remove the rear main bearing cap side seals.
  2.  

When removing the main bearing caps, be sure to keep the parts in order for installation purposes.

  1. Remove the rear main oil seal from around the crankshaft.
  2.  
  3. Remove the crankshaft, then lift the main bearings from the engine block.
  4.  
  5. Using a putty knife, clean the gasket mounting surfaces. Clean and inspect the engine parts.
  6.  
  7. To install, use new bearings (apply sealant to the rear main bearing caps) and oil seals, then the main bearing caps. Tighten the main bearing cap bolts (evenly, in three stages) to 33-40 ft. lbs. (56-52 Nm).
  8.  


WARNING
After torquing each of the main or connecting rod bearing caps, turn the crankshaft to make sure that crankshaft turns and the engine is not locked.

  1. Apply sealant to the rear main bearing cap side seals and install the side seals, driving the seals into place with a drift.
  2.  

When installing the new main or connecting rod bearings, be sure that the bearings surfaces are clean (free of dirt), lubricated, the oil holes are aligned and the bearings are seated with the aligning notches in their respective slots.

  1. To complete the installation, use new gaskets, sealant and reverse the removal procedures. Tighten the connecting rod cap bolts to 33-40 ft. lbs. (56-62 Nm), the oil pan bolts to 4-7 ft. lbs. (5-9 Nm), the flywheel-to-crankshaft bolts to 94-108 ft. lbs. (122-140 Nm), or the drive plate-to-crankshaft bolts to 94-108 ft. lbs. (122-140 Nm). Refill the crankcase and the cooling system; if equipped with an automatic transmission, check the fluid. Start the engine and adjust the timing.
  2.  

VG Engines

See Figures 7 and 8

  1. Refer to the Engine removal and installation procedures in this section, then remove the engine with the transmission from the vehicle. Separate the transmission from the engine and mount the engine on a workstand.
  2.  

If removing an automatic transmission from the engine, be sure to remove the torque converter-to-drive plate bolts, first.

  1. Remove the clutch assembly from the flywheel (manual transmission) or the torque converter from the drive plate (automatic transmission).
  2.  
  3. Remove the flywheel or the drive plate from the crankshaft, then secure the engine to a work stand.
  4.  
  5. Refer the Oil Pump removal and installation procedures in this section, and remove the oil pump from the engine.
  6.  



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Fig. Fig. 7: Main bearing cap components-1984-88 models



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Fig. Fig. 8: Bearing cap torque sequence-1984-88 models

  1. Remove the connecting rod bearing cap bolts and the bearing caps, then push the connecting rods away from the crankshaft.
  2.  

The connecting rod bearing caps are numbered, be sure to keep the parts in order for installation purposes. Be sure to slip short pieces of hose over the connecting rod studs, to prevent damaging the crankshaft bearing surfaces.

  1. Remove the main bearing cap bolts and the main bearing caps. Remove the rear oil seal retainer.
  2.  

When removing the main bearing caps, be sure to keep the parts in order for installation purposes.

  1. Remove the crankshaft, then lift the main bearings from the engine block.
  2.  
  3. Using a putty knife, clean the gasket mounting surfaces. Clean and inspect the engine parts.
  4.  
  5. To install, use new main bearings and oil seals, then the main bearing caps. Tighten the main bearing cap bolts (evenly, in three stages) to 67-74 ft. lbs. (87-96 Nm).
  6.  


WARNING
After torquing each of the main or connecting rod bearing caps, turn the crankshaft to make sure that the crankshaft turns and the engine is not locked.

When installing the new main or connecting rod bearings, be sure that the bearings surfaces are clean (free of dirt), lubricated, the oil holes are aligned and the bearings are seated with the aligning notches in their respective slots.

  1. To complete the installation, use new gaskets, sealant and reverse the removal procedures. Tighten the connecting rod cap bolts to 33-40 ft. lbs. (43-52 Nm), the oil pan bolts to 4-5 ft. lbs. (5-6 Nm), the flywheel-to-crankshaft bolts to 72-80 ft. lbs. (94-104 Nm) or the drive plate-to-crankshaft bolts to 72-80 ft. lbs. (94-104 Nm). Refill the crankcase and the cooling system; if equipped with an automatic transmission, check the fluid. Start the engine and adjust the timing.
  2.  

CLEANING AND INSPECTION



Crankshaft

See Figures 9, 10, 11 and 12

  1. Using solvent clean the crankshaft of debris and oil.
  2.  
  3. Inspect the crankshaft for scoring, wear or cracks.
  4.  



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Fig. Fig. 9: Measure the journals for out-of-round and taper conditions



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Fig. Fig. 10: Using a dial indicator to measure crankshaft run-out



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Fig. Fig. 11: Use the dial indicator and a suitable prytool to measure end-play



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Fig. Fig. 12: Checking the side clearance between the connecting rod and bearing cap

  1. Using an outside micrometer, check the crankshaft's connecting rod journals for taper and out-of-round conditions:
    1. To measure the journal's taper, make a measurement at each end of the connecting rod journal.
    2.  
    3. Make a second measurement at 90° to the first two measurements, then compare the measurements for an out-of-round condition. If the out-of-round measurement difference is greater than 0.005mm, the connecting rod journals must be reground.
    4.  
    5. Compare the measurements at each end of the connecting rod journals for taper conditions. If the taper measurement difference is greater than 0.005mm, the connecting rod journals must be reground.
    6.  

  2.  
  3. Position the crankshaft between two V-blocks, then position a dial indicator so that it will ride on a main bearing journal.
    1. Turn the crankshaft and check the journal run-out.
    2.  
    3. If the run-out is greater than 0.10mm, regrind the main bearing journals.
    4.  

  4.  
  5. Once the main bearings have been installed, check the crankshaft end-play:
    1. Push the crankshaft (in one direction) all of the way until it stops.
    2.  
    3. Using a dial indicator, place the indicator against the end of the crankshaft and zero the dial.
    4.  
    5. Using a feeler gauge, measure the gap between the thrust bearing and the crankshaft.
    6.  

  6.  

The crankshaft end-play should be 0.05-0.17mm; if it is greater than 0.30mm, replace the thrust bearing with a thicker one.

    1. Push the crankshaft (all the way) in the opposite direction. Using the dial indicator, measure the difference of the crankshaft (end direction) movement.
    2.  


  1. To check the connecting rod-to-crankshaft side clearance, perform the following:
    1. Push the connecting rod to the extreme side of the crankshaft pin.
    2.  
    3. Using a feeler gauge, insert it into the connecting rod-to-crankshaft gap and check the side clearance.
    4.  

  2.  

The connecting rod clearance should be 0.008-0.013 in. (0.20-0.35mm) for the VG engine or 0.008-0.011 in. (0.20-0.30mm) for all engines, except VG. If the gap is larger that 0.016 in. (0.40mm) for the VG engine or 0.02 in. (0.6mm) for all engines, except VG, replace the connecting rod.

BEARING REPLACEMENT



See Figure 13

After performing the main bearing installation, proceed with the connecting rod bearing installation, using the same method of installation.

  1. Install the new main bearings into the engine block. Make sure that the bearing oil holes align with the engine block oil holes and that the bearing tabs are seated into the journal notches.
  2.  
  3. Install the other half of the main bearing into the bearing caps, making sure that the bearing tabs are seated into the bearing cap notches.
  4.  



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Fig. Fig. 13: Measure the Plastigage® to determine the main bearing clearance

  1. Install the crankshaft into the engine block.
  2.  
  3. Using the Plastigage® method of checking the bearing clearance, place a piece of Plastigage® onto each main bearing surface.
  4.  
  5. Install the main bearing caps and torque to specifications.
  6.  
  7. After all of the main bearings have been tightened to specifications, remove the main bearing caps.
  8.  
  9. Using the width gauge (supplied with each Plastigage® kit), compare the gauge with the squashed Plastigage® strip.
  10.  

The width of the squashed Plastigage® will relate to the bearing clearance. If necessary, replace the bearing(s) to acquire the correct bearing clearance.

  1. With the bearing correct, remove the Plastigage® material, oil the bearing surface, install the bearing cap and tighten it to specifications.
  2.  

 
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