Bearing - Clearance
BEARING CLEARANCEEither of the following two methods may be used, however, method A gives more reliable results and is preferable.
Method A (Using bore gauge & micrometer)
Main Bearing
1. Set main bearings in their proper positions on cylinder block and main bearing cap.
2. Install main bearing cap 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.
No. 1 Main bearing clearance (A - Dm):
Standard 0.030 - 0.048 mm (0.0012 - 0.0019 inch)
Limit 0.060 mm (0.0024 inch)
No. 2, 3, 4 Main bearing clearance (A - Dm):
Standard 0.038 - 0.065 mm (0.0015 - 0.0026 inch)
Limit 0.080 mm (0.0031 inch)
6. If it exceeds the limit, replace bearing.
7. If clearance cannot be adjusted within the standard of any bearing, grind crankshaft journal and use undersized bearing.
a. When grinding crankshaft journal, confirm that "L" dimension in fillet roll is more than the specified limit.
"L": 0.1 mm (0.004 inch)
b. Grind the crankshaft to specification, and use available service parts. Refer to Engine; Specifications; Mechanical.
8. If crankshaft is reused, measure main bearing clearances and select thickness of main bearings.
If crankshaft is replaced with a new one, it is necessary to 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.
No. 1 main bearing grade number (Identification color):
Except No. 1 main bearing grade number (Identification color):
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 example or table.
Connecting Rod Bearing (Big end)
1. Install connecting rod bearing to connecting rod and cap.
2. Install connecting rod cap to connecting rod.
Tighten bolts to the specified torque.
3. Measure inner diameter "C" of each bearing.
4. Measure outer diameter "Dp" of each crankshaft pin journal.
5. Calculate connecting rod bearing clearance.
Connecting rod bearing clearance (C - Dp):
Standard 0.024 - 0.064 mm (0.0009 - 0.0025 inch)
Limit 0.090 mm (0.0035 inch)
6. If it exceeds the limit, replace bearing.
7. If clearance cannot be adjusted within the standard of any bearing, grind crankshaft journal and use undersized bearing. Refer to Engine; Specifications; Mechanical.
Method B (Using plastigage)
CAUTION: Do not turn crankshaft or connecting rod while plastigage is being inserted.
When bearing clearance exceeds the specified limit, ensure that the proper bearing has been installed. Then if excessive bearing clearance exists, use a thicker main bearing or undersized bearing so that the specified bearing clearance is obtained.