Tools Required

J 36660-A Torque/Angle Meter

Important: If the crankshaft bearings have been used in a running engine, you must replace them with NEW crankshaft bearings for reassembly.

1. Clean the upper and lower crankcase crank bore with a lint-free cloth.



2. Clean all the oil from the backside of new bearing halves.
3. Install new upper crankshaft bearings into position. The thrust bearing (1) belongs in the number three journal. Be sure the upper bearing insert contains the oil transfer hole and groove. Roll the bearing into position so that the lock tang engages the crank slot. The bearing must fit flush with the upper crankcase.



4. Install new lower crankshaft bearings into position in the lower crankcase. The lower crankcase crankshaft bearings are identified by NO grooves or holes. The bearings must fit flush with the lower crankcase.
5. Apply a liberal amount of GM crankshaft prelube GM P/N 1052367 or engine oil to the upper and lower bearing surfaces.

1. Install the crankshaft sprocket drive key (1). If necessary, lightly tap the key in place with a small hammer until it bottoms on the crankshaft.



2. Gently lower the crankshaft into position in the cylinder block.
3. Make sure the crankshaft turns without binding or noise.

1. Place a length of fresh, room temperature plastic gaging material all the way across all the crankshaft bearing journals.



2. Align the lower crankcase with the dowel pins in the upper crankcase.
3. Install the lower crankcase onto the upper crankcase slowly until feeling a positive stop.
4. Inspect the upper-to-lower crankcase joint in order to make sure the lower crankcase is fully seated on the cylinder block.



5. Install the oil manifold plate.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

6. Install the oil manifold plate retaining bolts.

Tighten
Tighten the oil manifold plate bolts to 10 N·m (89 lb in).




7. Place the crankshaft oil scraper in position on the oil manifold. Align the holes with the main bearing bolt holes.
8. Install the main bearing bolts. The single stud-head bolt (1) used for oil pump pick-up mounting goes in the inboard position of the third set of main bearing bolts from the front of the engine.



9. Install the left side upper-to-lower crankcase perimeter bolts.



10. Install the right side upper-to-lower crankcase perimeter bolts.



11. Tighten the lower crankcase bolts in proper sequence.

11.1.

First Pass

Tighten
Tighten the lower crankcase bearing bolts (numbers 1 through 20) to 20 N·m (15 lb ft) in the proper sequence.

11.2.

Final Pass

Tighten
Tighten the lower crankcase bolts (numbers 1 through 20) an additional 65 degrees in the proper sequence using the J 36660-A .




12. Tighten the upper-to-lower crankcase perimeter bolts (numbers 1 through 8).

Tighten
Tighten the upper-to-lower crankcase perimeter bolts (numbers 1 through 8) to 30 N·m (22 lb ft).

13. Allow the assembly to sit for at least two minutes.
14. Remove the main bearing bolts.
15. Remove the oil scraper.
16. Remove the oil manifold retaining bolts and oil manifold.
17. Remove the lower crankcase.



18. Determine the main bearing clearance by comparing the width of the flattened plastic gaging material at its widest point with the graduation on the gaging material container.
19. Compare your measurements with the engine mechanical specifications. If the new bearings do not provide the proper crankshaft to bearing clearance, re-measure the crankshaft journals for the correct specified size and check to make sure you have the correct new bearings. If the crankshaft journals are incorrectly sized, replace the crankshaft. No crankshaft machining is permitted and undersized bearings are not available.
20. Clean the plastic gaging material from the crankshaft bearings and/or crankshaft bearing journals using a soft lint-free cloth.
21. Coat the upper crankshaft bearings and crankshaft main bearing journals with GM crankshaft prelube GM P/N 1052367 or equivalent.



22. Reinstall the crankshaft into position in the cylinder block.