BEARING REPLACEMENT

Main bearing clearances must be corrected by the use of selective upper and lower shells. Undersized bearings are available in sizes of 0.25mm, 0.50mm and 0.75mm. UNDER NO CIRCUMSTANCES should the use of shims behind the shells to compensate for wear be attempted. To install the main bearing shells, proceed as follows:

1. Remove the oil pan as outlined below. On some models, the oil pump may also have to be removed.
2. Loosen all main bearing caps.
3. Remove the bearing cap and remove the lower shell.
4. Insert a flattened cotter pin or roll pin in the oil passage hole in the crankshaft, then rotate the crankshaft in the direction opposite to cranking rotation. The pin will contact the upper shell and roll it out.
5. The main bearing journals should be checked for roughness and wear. Slight roughness may be removed with a fine grit polishing cloth saturated with engine oil. Burrs may be removed with a fine oil stone. If the journals are scored or ridged, the crankshaft must be replaced.

   The journals can be measured for out-of-round with the crankshaft installed by using a crankshaft caliper and inside micrometer or a main bearing micrometer. The upper bearing shell must be removed when measuring the crankshaft journals. Maximum out-of-round of the crankshaft journals must not exceed 0.050mm (0.00197 in.).

6. Clean the crankshaft journals and bearing caps thoroughly for installing new main bearings.
7. Apply clean engine oil or rebuilding oil, to the thrust flanges of bearing shells.
8. Place a new upper shell on the crankshaft journal with locating tang in the correct position and rotate the shaft to turn it into place using a cotter pin or roll pin as during removal.
9. Place a new bearing shell in the bearing cap.
10. Install a new oil seal in the rear main bearing cap and block.
11. Lubricate the main bearings with engine oil. Lubricate the thrust surface with lubricant rebuilding oil.
12. Lubricate the main bearing cap bolts with engine oil.

    NOTE: In order to prevent the possibility of cylinder block and/or main bearing cap damage, the main bearing caps are to be tapped into their cylinder block cavity using a wood or rubber mallet before the attaching bolts are installed. Do not use attaching bolts to pull the main bearing caps into their seats. Failure to observe this information may damage the cylinder block or a bearing cap.

13. Torque the main bearing cap bolts as specified.