Acura Coupes and Sedans 1986-1993 Repair Guide

Crankshaft and Main Bearings

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REMOVAL & INSTALLATION



1.6L, 2.5L (V6) and 2.7L Engines

These engines use a main bearing cap and separate bridge assembly. THe bridge assembly serves as an added stiffener to the bottom of the engine.

  1. Remove the engine from the vehicle and place it on a work stand.
  2.  
  3. Remove the crankshaft pulley attaching bolts and washer.
  4.  
  5. Remove the front cover and the air conditioning idler pulley assembly, if so equipped. Remove cover assembly.
  6.  
  7. Check the timing belt deflection. Remove the timing belt and sprockets.
  8.  
  9. Invert the engine on work stand. Remove the flywheel and the rear seal cover. Remove the oil pan and gasket. Remove the oil pump inlet and the oil pump assembly.
  10.  
  11. Ensure all bearing caps (main and connecting rod) are marked so they can be installed in their original positions. Turn the crankshaft until the connecting rod from which cap is being removed is up. Remove the connecting rod cap. Push the connecting rod and piston assembly up in the cylinder. Repeat the procedure for the remaining connecting rod assemblies.
  12.  
  13. Remove the main bearing caps.
  14.  
  15. Carefully lift crankshaft out of block so upper thrust bearing surfaces are not damaged.
  16.  


WARNING
Handle the crankshaft with care to avoid possible fracture or damage to the finished surfaces.

To install:

If the bearings are to be reused they should be identified to ensure that they are installed in their original position.

  1. Remove the main bearing inserts from the block and bearing caps.
  2.  
  3. Remove the connecting rod bearing inserts from connecting rods and caps.
  4.  
  5. Install a new rear oil seal in rear seal cover.
  6.  
  7. Apply a thin coat of Polyethylene Grease to the rear crankshaft surface. Do not apply sealer to the area forward of oil sealer groove. Inspect all the machined surfaces on the crankshaft for nicks, scratches or scores which could cause premature bearing wear.
  8.  
  9. If the crankshaft main bearing journals have been refinished to a definite undersize, install the correct undersize bearings. Ensure the bearing inserts and bearing bores are clean. Foreign material under the inserts will distort the bearing and cause a failure.
  10.  
  11. Place the upper main bearing inserts in position in the bores with the tang fitted in the slot provided.
  12.  
  13. Install the lower main bearings inserts in the bearing caps.
  14.  
  15. Carefully lower the crankshaft into place.
  16.  
  17. Check the clearance of each main bearing. Select fit the bearings for proper clearance.
  18.  
  19. After the bearings have been fitted, apply a light coat of heavy engine oil, SAE 50 weight to journals and bearings. Install all the bearing caps.
  20.  

The main bearing cap must be installed in their original positions.

  1. Align the upper thrust bearing.
  2.  
  3. Check the crankshaft end play.
  4.  
  5. If the end play exceeds specification, replace the upper thrust bearing. If the end play is less than the specification, inspect the thrust bearing faces for damage, dirt or improper alignment. Install the thrust bearing and align the faces. Check the end-play.
  6.  
  7. Install the new bearing inserts in the connecting rods and caps. Check the clearance of each bearing.
  8.  
  9. If the bearing clearances are to specification, apply a light coat of heavy engine oil, SAE 50 weight to the journals and bearings.
  10.  
  11. Turn the crankshaft throw to the bottom of the stroke. Push the piston all the way down until the rod bearings seat on the crankshaft journal.
  12.  
  13. Install the connecting rod cap.
  14.  
  15. After the piston and connecting rod assemblies have been installed, check the connecting rod crankshaft journal.
  16.  
  17. Turn the engine on the work stand so the front end is up. Install the timing belt, sprockets, front cover, oil seal and the crankshaft pulley.
  18.  
  19. Clean the oil pan, oil pump and the oil pump screen assembly.
  20.  
  21. Prime the oil pump by filling the inlet opening with oil and rotating the pump shaft until oil emerges from the outlet opening. Install the oil pump.
  22.  
  23. Position the flywheel on the crankshaft. Install the attaching bolts. Tighten to specification.
  24.  

On the flywheel (manual transaxle only) locate clutch disc and install pressure plate.

  1. Turn the engine on the work stand so the engine is in the normal upright position. Install the oil level dipstick. Install the accessory drive pulley, if so equipped. Install and adjust the drive belt and the accessory belts to specification.
  2.  
  3. Install either the clutch assembly or the torque converter.
  4.  
  5. Install the oil pan.
  6.  
  7. Remove the engine from work stand. Install the engine in the vehicle.
  8.  

1.7L, 1.8L and 2.5L (5 Cylinder) Engines
  1. Remove the engine assembly from the vehicle and install on a suitable workstand.
  2.  
  3. Remove the cylinder head, oil pan, oil pump and the flywheel.
  4.  
  5. Remove the piston and connecting rod assemblies. Refer to the procedure in this Section.
  6.  
  7. Remove the rear main seal housing.
  8.  
  9. Make sure the main bearing caps are numbered so they can be reinstalled in their original positions. Remove the bolts, then remove the bearing caps.
  10.  
  11. Lift the crankshaft from the cylinder block.
  12.  
  13. Inspect the crankshaft and bearings and repair and/or replace as necessary.
  14.  

To install:
  1. After cleaning, inspecting and measuring the crankshaft and checking the main bearing clearance, install the crankshaft. Apply engine assembly lube or clean engine oil to the upper bearing shells prior to installation.
  2.  
  3. Apply engine assembly lube or clean engine oil to the lower bearing shells, then install the main bearing caps in their original positions. Tighten the bolts to the specification.
  4.  
  5. After each cap is tightened, check to see and feel that the crankshaft can be rotated by hand. If not, remove the bearing cap and check for the source of the interference.
  6.  
  7. Install the rear main seal housing and the flywheel.
  8.  
  9. Install the piston and connecting rod assemblies.
  10.  
  11. Install the oil pump and the oil pan.
  12.  
  13. Install the cylinder head.
  14.  
  15. Install the engine assembly in the vehicle.
  16.  

3.2L Engines

See Figures 1 through 8

  1. Remove the engine assembly from the vehicle and install on a suitable workstand.
  2.  
  3. Remove the accessory drive belt, water pump belt, water pump and pump mounting bracket.
  4.  
  5. Remove the crankshaft damper and the timing chain cover.
  6.  
  7. Remove the timing chain and sprockets.
  8.  
  9. Remove the flywheel. Remove the oil pan and the oil pump and intermediate shaft assembly.
  10.  
  11. Make sure all connecting rod and main bearing caps are numbered so they can be reinstalled in their original positions. Turn the crankshaft until the connecting rod from which the cap is being removed is up, then remove the cap.
  12.  
  13. Install snug-fitting rubber hoses over the rod bolts, to prevent damaging the crankshaft, then push the piston and connecting rod assembly up in the cylinder. Repeat this procedure for the remaining piston and connecting rod assemblies.
  14.  
  15. Remove the main bearing caps.
  16.  
  17. Lift the crankshaft from the cylinder block.
  18.  
  19. Inspect the crankshaft and bearings and repair and/or replace as necessary.
  20.  

To install:
  1. After cleaning, inspecting and measuring the crankshaft and checking the main and connecting rod bearing clearance, install the crankshaft. Apply engine assembly lube or clean engine oil to the upper main bearing shells prior to installation.
  2.  
  3. Apply engine assembly lube or clean engine oil to the lower bearing shells, then install the main bearing caps in their original positions. Apply RTV sealer to the rear main bearing cap parting line on the cylinder block.
  4.  
  5. Before tightening the main cap bolts, pry the crankshaft forward against the thrust surface of the upper thrust bearing shell. Hold the thrust bearing cap to the rear to align the thrust surfaces of both halves of the bearing.
  6.  
  7. Lubricate the upper connecting rod bearing shells with engine assembly lube or clean engine oil. Turn the crankshaft until the connecting rod journal is at the bottom of the stroke, then pull the piston and connecting rod assembly toward the journal until it is seated on the crankshaft.
  8.  
  9. Lubricate the lower connecting rod bearing shells with engine assembly lube or clean engine oil, then install the rod cap. Tighten the connecting rod nuts to specification. After all connecting rods have been installed on the crankshaft, check the connecting rod side clearance.
  10.  
  11. Install the timing chain, sprockets, timing cover and crankshaft damper.
  12.  
  13. Install a new rear main seal.
  14.  
  15. Clean the oil pan, oil pump and screen. Prime the oil pump by filling the inlet opening with oil and rotating the pump shaft until oil emerges from the outlet opening. Install the oil pump and intermediate shaft assembly.
  16.  
  17. Install the oil pan and the flywheel.
  18.  
  19. Install the water pump, pump mounting bracket, water pump belt and accessory drive belt.
  20.  
  21. Install the engine assembly in the vehicle.
  22.  



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Fig. Fig. 1: Main bearing cap identification-1986-90 Legend



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Fig. Fig. 2: Installing the main bearing bolts-1986-90 Legend



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Fig. Fig. 3: Main bearing selection and identification-1986-90 Integra 1.6L



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Fig. Fig. 4: Crankshaft and main bearing installation-1991-93 Legend



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Fig. Fig. 5: Main bearing cap identification and installation-1991-93 Legend



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Fig. Fig. 6: Main bearing cap bolt torque sequence-1991-93 Legend



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Fig. Fig. 7: Main bearing cap bolt loosening sequence-Vigor



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Fig. Fig. 8: Main bearing cap bolt torque sequence

CLEANING AND INSPECTION



  1. Clean the crankshaft with solvent and a brush. Clean the oil passages with a suitable brush, then blow them out with compressed air.
  2.  
  3. Inspect the crankshaft for obvious damage or wear. Check the main and connecting rod journals for cracks, scratches, grooves or scores. Inspect the crankshaft oil seal surface for nicks, sharp edges or burrs that could damage the oil seal or cause premature seal wear.
  4.  
  5. If the crankshaft passes a visual inspection, measure the main and connecting rod journals for wear, out-of-roundness or taper, using a micrometer. Measure in at least 4 places around each journal and compare your findings with the journal diameter specifications.
  6.  
  7. If equipped with a manual transaxle, check the fit of the clutch pilot bearing in the bore of the crankshaft. The bearing is pressed into the crankshaft and should not be loose. Inspect the inner surface of the bearing for wear or a bell-mouth condition. Check the inside diameter of the bearing for wear or damage. Check the bearing for roughness, evidence of overheating, or loss of lubricant and replace, as necessary.
  8.  
  9. Check journal runout using a dial indicator. Support the crankshaft in V-blocks and check the runout as shown. Compare to specifications.
  10.  
  11. If the crankshaft fails any inspection for wear or damage, it must be reground or replaced.
  12.  

BEARING REPLACEMENT



See Figures 9 and 10

  1. Inspect the bearings for scoring, chipping or other wear.
  2.  
  3. Inspect the crankshaft journals as detailed in the Cleaning and Inspection procedure.
  4.  
  5. If the crankshaft journals appear usable, clean them and the bearing shells until they are completely free of oil. Blow any oil from the oil hole in the crankshaft.
  6.  

The journal surfaces and bearing shells must be completely free of oil to get an accurate reading with Plastigage®.

  1. Place a strip of Plastigage® lengthwise along the bottom center of the lower bearing shell, then install the cap with the shell and torque the connecting rod nuts or main cap bolts to specification. Do not turn the crankshaft with the Plastigage® installed in the bearing.
  2.  
  3. Remove the bearing cap with the shell. The flattened Plastigage® will either be sticking to the bearing shell or the crankshaft journal.
  4.  
  5. Using the printed scale on the Plastigage® package, measure the flattened Plastigage® at its widest point. The number on the scale that most closely corresponds to the width of the Plastigage® indicates the bearing clearance in thousandths of an inch or hundreths of a millimeter.
  6.  
  7. Compare your findings with the bearing clearance specification. If the bearing clearance is excessive, the bearing must be replaced or the crankshaft must be ground and the bearing replaced.
  8.  

If the crankshaft is still at standard size (has not been ground undersize), bearing shell sets of 0.001 in. , (0.0254mm) 0.002 in. (0.050mm) and 0.003 in. (0.0762mm) over standard size are available to correct excessive bearing clearance.

  1. After clearance measuring is completed, be sure to remove the Plastigage® from the crankshaft and/or bearing shell.
  2.  



Click image to see an enlarged view

Fig. Fig. 9: Checking the crankshaft runout using a dial indicator

  1. For final bearing shell installation, make sure the connecting rod and rod cap and/or cylinder block and main cap bearing saddles are clean and free of nicks or burrs. Install the bearing shells in the bearing saddles, making sure the bearing shell tangs are seated in the notches.
  2.  

Be careful when handling any plain bearings. Your hands and the working area should be clean. Dirt is easily embedded in the bearing surface and the bearings are easily scratched or damaged.

  1. After all of the main bearing cap bolts have been tightened, mount a dial indicator on the end of the cylinder block with the indicator foot resting on the end of the crankshaft. Move the crankshaft back and forth with a prybar, being careful not to damage the crankshaft, bearings or cylinder block, and observe the dial indicator. Check the reading against the crankshaft end-play specification. If the end-play is excessive, it can be corrected using a thicker thrust bearing or by removing the crankshaft and welding and regrinding the thrust journal.
  2.  



Click image to see an enlarged view

Fig. Fig. 10: Checking the crankshaft for out-of-round and taper

 
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