Crankshaft Main Bearing Replacement

Crankshaft Main Bearing Replacement

Main Bearing Clearance Inspection

1. To check the main bearing-to-journal oil clearance, remove the lower block and the bearing halves Crankshaft And Piston Removal.

2. Clean each main journal and the bearing half with a clean shop towel.

3. Place one strip of plastigage across each main journal.

4. Reinstall the bearings and the lower block, then tighten the bolts to 29 Nm (3.0 kg-m, 22 lb-ft).

NOTE:

- Apply new engine oil to the bolt threads and flanges.
- Do not rotate the crankshaft during inspection.





5. Tighten the bearing cap bolts an additional 48 °.

6. Remove the lower block and the bearings again, and measure the widest part of the plastigage.













7. If the plastigage measures too wide or too narrow, remove the crankshaft, and remove the upper half of the bearing. Install a new, complete bearing with the appropriate color code(s), and recheck the clearance. Do not file, shim, or scrape the bearings or the caps to adjust clearance.

8. If the plastigage shows the clearance is still incorrect, try the next larger or smaller bearing (the color listed above or below the current one), and check again. If the proper clearance cannot be obtained by using the appropriate larger or smaller bearings, replace the crankshaft and start over Crankshaft And Piston Removal.

Main Bearing Selection

Block Bore Code Location

Numbers, letters, or bars have been stamped on the end of the block as a code for the size of each of the five main journal bores.

Use them, and the numbers or bars stamped on the crankshaft (codes for main journal size), to choose the correct bearings. If the codes are indecipherable because of an accumulation of dirt and dust, do not scrub them with a wire brush or scraper. Clean them only with solvent or detergent.










Main Journal Code Location