Chevrolet Chevette/1000 1976-1988 Repair Guide

Crankshaft and Main Bearings (Diesel Engine)

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REMOVAL & INSTALLATION



  1. Remove the engine as previously outlined in this section.
  2.  
  3. Remove the fan and pulley.
  4.  
  5. Remove the upper dust cover.
  6.  
  7. Remove the lower cover.
  8.  
  9. Remove the timing belt cover.
  10.  
  11. Remove the cam cover.
  12.  
  13. Rotate the crankshaft and install a camshaft holding tool No. J-29761, or equivalent, then install an injection pump lockbolt. Refer to Injection Pump removal and installation in .
  14.  
  15. Remove the adjusting spring.
  16.  
  17. Remove the cam gear.
  18.  
  19. Remove the crankshaft hub and gear.
  20.  
  21. Remove the front cover bolts.
  22.  
  23. Rotate the engine on the stand.
  24.  
  25. Remove the oil pan front cover.
  26.  
  27. Remove the oil strainer.
  28.  
  29. Remove the connecting rod caps.
  30.  
  31. Remove the rear main caps.
  32.  
  33. Remove the flywheel or flexplate.
  34.  
  35. Remove the crankshaft.
  36.  

INSPECTION





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Fig. Fig. 1Check for crankshaft runout using a dial indicator



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Fig. Fig. 2Measure the crankshaft journal and pin diameter



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Fig. Fig. 3Bearing and journal clearance



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Fig. Fig. 4Measuring the pin and bearing clearance



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Fig. Fig. 5Place a suitable gauging material on the journal



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Fig. Fig. 6Measure the gauging material against the scale on the packet



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Fig. Fig. 7Check the crankshaft end-play and compare to specifications

  1. Check the faces of the crankshaft journals, crankpin and oil seal fitting faces for wear and damage, and oil port restrictions. No attempt should be made to grind finish the faces of the crankshaft journals and crankpins.
  2.  
  3. Support the crankshaft on aligner or V-blocks at #1 and #5 journals and check for runout by turning the crankshaft carefully in one direction with the probe of a dial indicator resting on #3 journal. Take the highest reading. If the amount of runout is greater than 0.06mm, correct or replace the crankshaft.
  4.  
  5. Measure the diameters of the crankshaft journals and crankpins at the front and rear (I and II) in directions of A and B, to determine the amount of wear and taper wear. Standard Journal Diameter:

    55.92-55.935mm
     

  6.  

Standard Pin Diameter:



48.925-48.94mm
 

Inspect and measure bearing inside diameter as follows:

    1. Check the inner face of the bearings for pin holes, separation or sculling. Replace the entire set of bearing if any of them are found to be defective.
    2.  
    3. Install crankshaft bearings into position on the cylinder blocks. Then install the bearing caps and bolts. Tighten the bearing cap bolts to 100 Nm (75 ft. lbs.) and measure the inside diameter with an inside micrometer or a cylinder bore indicator. Standard bearing and journal clearance is 0.039-0.08mm.
    4.  
    5. Install the connecting rod bearing on the rod big end with the bearing cap. Install and torque the bearing cap bolts to 80 Nm (60 ft. lbs.), then measure the inside diameter of the bearing with an inside micrometer or a cylinder bore indicator.
    6.  


Pin and bearing clearance:



Standard-0.04-0.07mm
 
Limit-0.12mm
 

Measurement of clearance with gauging plastic.

    1. Wipe the crankshaft journals and crankpins to remove oil.
    2.  
    3. Install the bearings on the cylinder block and mount the crankshaft in position carefully; then turn the crankshaft about thirty degrees to ensure a good contact between the crankshaft and bearings.
    4.  
    5. Position gauging plastic over the crankshaft journal in direction in line with the axis of the crankshaft, so that it covers the entire width of the bearing.
    6.  
    7. Install the bearing cap and tighten the bearing cap bolts to 95 Nm (70 ft. lbs.). Do not turn the crankshaft with gauging plastic installed.
    8.  
    9. Remove the bearing cap and check the width of the gauging plastic against the scale printed on the packet.
    10.  
    11. Follow the same steps to measure the oil clearance between the crankpins and bearings.
    12.  


Check crankshaft end-play as follows:

    1. Install the bearings on the cylinder block and position the crankshaft over the bearings.
    2.  
    3. Install the thrust bearing in position on both sides of the #3 journal.
    4.  
    5. Move the crankshaft fully endwise and check the clearance between the crankshaft and thrust bearing using a feeler gauge. If the clearance is greater than 0.3mm, replace the thrust bearings with new ones; standard value is 0.06-0.24mm.
    6.  


INSTALLATION





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Fig. Fig. 8Main bearing installation for diesel engines



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Fig. Fig. 9Main bearing cap bolt tightening sequence

  1. Install the bearings properly and apply generous amounts of engine oil to the inner face of the bearings. Position the crankshaft over the bearings carefully, then install the thrust bearing. The bearings should be installed correctly in their respective position. Install the thrust bearing with the oil grooved side turned outward.
  2.  
  3. Apply a coat of silicone gasket evenly to the joining faces of the No. 5 bearing caps and cylinder body. The No. 1 and No. 5 bearing caps should be installed flush with the face of the cylinder body.
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  5. Apply engine oil to the threads and seating face of the bolts. Install the bearing caps in sequence of cylinder numbers with the arrow mark pointing toward the front of the engine and semitighten the bolts. Then retighten the bolts to 88-99 Nm (65-72 ft. lbs.).
  6.  

 
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