For 1990-2009 cars

Important: The upper main bearings have an oil groove and oil holes, the lower bearings do not have oil grooves or oil holes.

1. Install the upper main bearings into the cylinder block and lubricate with engine oil.
2. Install the lower main bearings into the lower crankcase and lubricate with engine oil.

Important: Install the upper thrust bearing washers with the oil groove (2) facing outward.

3. Install the two upper thrust bearing washers into the cylinder block and lubricate with engine oil.
4. Install the oil pump drive chain to the crankshaft gear.
5. Carefully place the crankshaft on to the main bearings in the cylinder block.
6. Thoroughly clean and remove any oil residue from the cylinder block mating surfaces.

Important: Avoid applying an excessive amount of sealant to the surface.

7. Apply a continuous bead of GM P/N 12345997 or equivalent sealant to the cylinder block mating rails.
8. Carefully place the lower crankcase assembly on to the cylinder block.
9. Gently tap the lower crankcase into place with a suitable tool.

Important: Gradual and uniform tightening is important for the lower crankcase bolts.

10. Install the ten main bearing cap bolts finger tight.

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.

11. Progressively torque the main bearing cap bolts (1-10) using two steps in the sequence shown.

Tighten

1. Tighten the main bearing cap bolts (1-10) to 42 N·m (31 lb ft).
2. Tighten the main bearing cap bolts (1-10) to 60 N·m (44 lb ft).

12. Install the twelve lower crankcase bolts. Progressively torque the lower crankcase bolts (11-22) using two steps in the sequence shown.

Tighten

1. Tighten the twelve lower crankcase bolts (11-22) to 19 N·m (14 lb ft).
2. Tighten the twelve lower crankcase bolts (11-22) to 27 N·m (20 lb ft).

13. Inspect that the crankshaft rotates smoothly by hand.