Crankshaft: Service and Repair

HOW TO SELECT PISTON AND BEARING

Main Bearing

HOW TO SELECT MAIN BEARING

When New Cylinder Block and Crankshaft Are Used
1. "Main Bearing Selection Table" rows correspond to main bearing housing grade on left side of cylinder block.

A : Basic stamp mark

Arrow Indicates Engine front

- If there is a corrected stamp mark (B) on cylinder block, use it as a correct reference.

2. Apply main journal diameter grade stamped on crankshaft front side to column in the "Main Bearing Selection Table".

A : Main journal diameter grade (No. 1 to 5 from left)
B : Crankshaft pin journal diameter grade (No. 1 to 4 from left)

3. Read the symbol at the cross point of selected row and column in the "Main Bearing Selection Table".
4. Apply the symbol obtained to the "Main Bearing Grade Table" to select main bearing.

NOTE:
Service part is available as a set of both upper and lower.

When Cylinder Block and Crankshaft Are Reused
1. Measure the dimensions of the cylinder block main bearing housing inner diameter and crankshaft main journal diameter individually. Refer to Inspection.
2. Apply the measured dimension to the "Main Bearing Selection Table".
3. Read the symbol at the cross point of selected row and column in the "Main Bearing Selection Table".
4. Apply the symbol obtained to the "Main Bearing Grade Table" to select main bearing.

Main Bearing Selection Table

Main Bearing Grade Table

Main Bearing Grade Table : Refer to "Main Bearing". Specifications

Use Undersize Bearing Usage Guide
- When the specified main bearing oil clearance is not obtained with standard size main bearings, use undersize (US) bearing.
- When using undersize (US) bearing, measure the main bearing inner diameter with bearing installed, and grind main journal so that the main bearing oil clearance satisfies the standard.

CAUTION:
In grinding crankshaft main journal to use undersize bearings, keep fillet R (A) [0.8 - 1.2 mm (0.031 - 0.047 in)].

Bearing undersize table: Refer to "Main Bearing". Specifications