Bearing - Clearance

BEARING CLEARANCE
Use Method A or Method B. Method A is preferred because it is more accurate.






Method A (Using bore gauge and micrometer)

Main bearing
1. Set main bearings in their proper positions on cylinder block and main bearing cap.
2. Install main bearing cap and main bearing beam to cylinder block. Tighten all bolts in correct order in two or three stages.






3. Measure inner diameter "A" of each main bearing.






4. Measure outer diameter "Dm" of each crankshaft main journal.
5. Calculate main bearing clearance.

Main bearing clearance = A - Dm
Standard: ............0.004 - 0.022 mm (0.0002 - 0.0009 inch)
Limit: .......0.050 mm (0.0020 inch)

If it exceeds the limit, replace bearing.
If clearance cannot be adjusted within the standard of any bearing, grind crankshaft main journal and use undersized bearing.






When grinding crankshaft journal, confirm that "L" dimension in fillet roll is more than the specified limit.

"L": ...........0.05 mm (0.0020 inch)

For grinding crankshaft and available service parts, refer to Engine; Specifications; Mechanical.







If crankshaft is replaced, select thickness of main bearings as follows:
a. Grade number of each cylinder block main journal is punched on the respective cylinder block. These numbers are punched in either Arabic or Roman numerals.









b. Grade number of each crankshaft main journal is punched on the respective crankshaft. These numbers are punched in either Arabic or Roman numerals.






c. Select main bearing with suitable thickness according to the table.
How to Select Piston and Bearing






Method B (Using Plastigage)


CAUTION: Do not turn crankshaft or connecting rod while Plastigage is being inserted.
If incorrect bearing clearance exists, use a thicker or undersized main bearing to ensure specified clearance.