Installation and Checking of Main Bearing Clearances

GENERAL INFORMATION

Selection of New Main Bearing Inserts Warning This procedure applies only to standard size main bearings. Repair bearings are not divided into size groups. New main bearings are selected according to the identification codes marked on the crankshaft and on the cylinder block.

The crankshaft codes are marked on the web of the No. 1 cylinder journal (timing chain cover side). The five-digit code refers to the main bearing journal diameters: the first digit is the code for the 1st main journal, and the fifth digit is the code for the 5th journal. Warning: On some engines, four-digit codes indicating the size group of the connecting rod bearings are also marked on the crankshaft web (see subsection 3.2.2.10.2).

The cylinder block size codes are stamped on the bottom surface on the flywheel side. To select the main bearing inserts, determine the size group of the main bearing bore stamped on the cylinder block and the size group code of the corresponding main journal marked on the crankshaft. Then use the table below to find the required insert, identified by the colored dot marked on its side surface.

Crankshaft Code / Cylinder Block Code / Main Bearing Insert Marking 0 0 black 0 1 brown 0 2 green 1 0 brown 1 1 green 1 2 yellow 2 0 green 2 1 yellow 2 2 blue Checking Main Bearing Clearances

PROCEDURE

1. Clean the outer surface of the new main bearing inserts, the bearing bores in the cylinder block and the main bearing caps.

2. Install the upper inserts, aligning the tabs with the recesses in the cylinder block (arrow).

3. Install the lower inserts in the caps, also aligning the tab with the recess (indicated by arrow).

4. Do not touch the bearing running surfaces with your fingers. Note that all upper main bearing inserts have an oil groove and an oil supply hole. The lower inserts are plain. If the clearance is checked using the old inserts, make sure they are installed in their original positions.

5. The clearance can be checked in two ways.

6. To determine the clearance using the first method, install the main bearing caps (or cap assembly) with the inserts onto the cylinder block, tighten the bolts to the specified torque, and measure the inside diameter of each assembled pair of inserts. The main bearing clearance is the difference between this diameter and the diameter of the crankshaft main journal.

7. The second method (more accurate) uses plastic gauge wire (Plastigage).

8. After installing the main bearing inserts in position, carefully lower the crankshaft into place. The main journals must be dry and clean.

9. Prepare several pieces of Plastigage, each slightly shorter than the width of the main bearing, and place one piece on each main journal of the crankshaft, parallel to its axis.

10. Install the caps with the lower inserts, without disturbing their orientation.

11. Tighten the bolts to the specified torque in the specified sequence. Tighten the bolts with equal, steadily increasing force. During tightening, the position of the wire pieces must not change, and the crankshaft must not be rotated.

12. In the reverse of the specified sequence, loosen the cap bolts, one turn at a time.

13. Remove the caps (or cap assembly) without disturbing the position of the flattened wire pieces and without rotating the crankshaft.

14. Compare the width of the crushed plastigage with the scale on the package and determine the main bearing clearance. Compare with the specified value.

15. If the clearance differs from the specification, the cause may be incorrect bearing selection, or excessive wear if used bearings were checked.

16. Before concluding that the bearings must be replaced, make sure there was no dirt or oil between the caps or cylinder block and the bearing during measurement.

17. If the width of the crushed wire is greater at one edge, this indicates taper of the journal.

18. If the clearance is out of specification when measured with used bearings, repeat the measurement with new bearings.

19. If the clearance still exceeds the specification with new bearings, consult an automotive service facility. It may be necessary to regrind the crankshaft journals and install undersize bearings.

20. If necessary, purchase bearings of the correct size group and repeat the main bearing clearance measurement procedure.

21. When finished, scrape off the remaining plastigage from the crankshaft main journals without damaging the surface.

Final Crankshaft Installation

PROCEDURE

1. Carefully remove the crankshaft from the cylinder block.

2. Install the main bearing inserts in their positions.

3. If new bearings are being installed, thoroughly wash them in kerosene.

4. Wipe the bearings and connecting rods dry.

5. Thoroughly lubricate the bearing surfaces installed in the cylinder block with fresh engine oil.

6. Apply a thin layer of multi-purpose grease to the thrust washers and install them on both sides of the No. 3 main bearing.

7. Make sure the oil grooves on both thrust washers face away from the cylinder block.

8. Install the crankshaft in the cylinder block and check the end play.

9. Thoroughly clean the grease from the mating surfaces of the main bearing caps and the cylinder block.

10. Lubricate the lower bearing surfaces with fresh engine oil. Make sure the locating tabs on the bearings engage the recesses in the caps.

11. Install the caps in their original positions, aligning them with the marks made during removal.

12. Tighten the bolts by hand.

13. Tighten the cap bolts in the specified sequence to approximately half the specified torque. Then, repeating the procedure, tighten the bolts to the specified torque.

14. Check that the crankshaft rotates freely.

15. Install the connecting rods with pistons.

16. Make a mark indicating the installed depth of the seal in the retainer, then remove the seal by prying it out with a screwdriver.

17. Drive in the new seal with light hammer blows to the depth indicated by the mark.

18. Apply a bead of sealant to the mating surface of the seal retainer and install it on the cylinder block.

19. Tighten the bolts to the specified torque.

20. Install the flywheel, camshaft timing chains and oil pan.