Crankshaft Main Bearing: Testing and Inspection
MAIN BEARINGSGeneral Information
^ Service main bearings are available in standard size and 0.25 mm (0.0098 inch) undersize, and each of them has five kinds of bearings differing in tolerance.
^ Upper half of bearing has oil groove as shown in figure. Install this half with oil groove to cylinder block.
^ On each main bearing cap, arrow mark and number are embossed as shown in figure. When installing each bearing cap to cylinder block, point arrow mark toward crankshaft pulley side and install each cap from that side to flywheel side in ascending order of numbers " 1", "2", "3", "4" and "5." Tighten cap bolts to specified torque.
Inspection
Check bearings for pitting, scratches, wear or damage. If any malcondition is found, replace both upper and lower halves. Never replace one half without replacing the other half.
MAIN BEARING CLEARANCE
Check clearance by using gaging plastic according to following procedure:
1. Remove bearing caps.
2. Clean bearings and main journals.
3. Place a piece of gaging plastic the full width of bearing (parallel to crankshaft) on journal, avoiding oil hole.
4. Install bearing cap as previously outlined and evenly toque cap bolts to specified torque. Bearing cap MUST be torqued to specification in order to assure proper reading of clearance.
Tightening Torque (a): 54 Nm (5.4 kg-m, 39.0 ft. lbs.).
NOTE: Do not rotate crankshaft while gaging plastic is installed.
5. Remove cap and using scale on gaging plastic envelope, measure gaging plastic width at its widest point. If clearance exceeds its limit, replace bearing. Always replace both upper and lower inserts as a unit.A new standard bearing may produce proper clearance. If not, it will be necessary to regrind crankshaft journal for use of 0.25 mm undersize bearing. After selecting new bearing, recheck clearance.
Bearing Clearance:
Standard: 0.020 - 0.040 mm (0.0008 - 0.0016 inch)
Limit: 0.060 mm (0.0023 inch)
SELECTION OF MAIN BEARINGS
Standard Bearing
If bearing is in malcondition, or bearing clearance is out of specification, select a new standard bearing according to following procedure and install it.
1. First check journal diameter by using following procedure. As shown in figure, crank webs of No.2 and No.3 cylinders have five stamped numerals. Three kinds of numerals ("1","2" and"3") represent following journal diameters.
Numeral Stamped: 1
Journal Diameter: 51.994- 52.000 mm (2.0470 - 2.0472 inch)
Numeral Stamped: 2
Journal Diameter: 51.988 - 51.994 mm (2.0468 - 2.0470 inch)
Numeral Stamped: 3
Journal Diameter: 51.982 - 51.988 mm (2.0465 - 2.0468 inch)
The first, second, third, fourth and fifth (left to right) stamped numerals represent journal diameters at bearing caps "1","2","3","4" and "5" respectively.
For example, in figure, the first (left most) numeral "3" indicates that journal diameter at bearing cap "1" is within 51.982 -51.988 mm, and second one "1" indicate that journal diameter at cap "2" is within 51.994 - 52.000 mm.
2. Next, check bearing cap bore diameter without bearing. On mating surface of cylinder block, four alphabets are stamped as shown in figure. Three kinds of alphabets ("A","B" and "C") represent following cap bore diameters.
Alphabet Stamped: A
Bearing Cap Bore Diameter (Without Bearing): 56.000 - 56.006 mm (2.2047 - 2.2050 inch)
Alphabet Stamped: B
Bearing Cap Bore Diameter (Without Bearing): 56.006 - 56.012 mm (2.2050 - 2.2052 inch)
Alphabet Stamped: C
Bearing Cap Bore Diameter (Without Bearing): 56.012 - 56.018 mm (2.2052 - 2.2054 inch)
The first, second, third, fourth, and fifth (left to right) stamped alphabets represent cap bore diameters of bearing caps "1","2","3","4", and "5", respectively. For example, in figure, the first (left most) alphabet "B" indicates that cap bore diameter of bearing cap "1" is within 56.006 - 56.012 mm, and the fifth (right most) alphabet "A" indicates that cap bore diameter of cap "5" is within 56.000 - 56.006 mm.
3. There are five kinds of standard bearings differing in thickness. To distinguish them, they are painted in following colors at the position as indicated in figure. Each color indicates following thickness at the center of bearing.
Color Painted: Green
Bearing Thickness: 1.996 - 2.000 mm (0.0786 - 0.0787 inch)
Color Painted: Black
Bearing Thickness: 1.999 - 2.003 mm (0.0787 - 0.0788 inch)
Color Painted: Colorless (no paint)
Bearing Thickness: 2.002 - 2.006 mm (0.0788 - 0.0789 inch)
Color Painted: Yellow
Bearing Thickness: 2.005 - 2.009 mm (0.0789 - 0.0790 inch)
Color Painted: Blue
Bearing Thickness: 2.008 - 2.012 mm (0.0790 - 0.0791 inch)
4. From numerals stamped on crank webs of No.2 and No.3 cylinders and the alphabets stamped on mating surface of cylinder block, determine new standard bearing to be installed to journal, by referring to table given below. For example, if numeral stamped on crank web is "1" and alphabet stamped on mating surface is "B",install a new standard bearing painted in "Black" to its journal.
Alphabet Stamped On Mating Surface (Bearing Cap Bore Diameter):
A:
1: Green
2: Black
3: Colorless
B:
1: Black
2: Colorless
3: Yellow
C:
1: Colorless
2: Yellow
3: Blue
New standard bearing to be installed.
5. Using gaging plastic, check bearing clearance with newly selected standard bearing. If clearance still exceeds its limit, use next thicker bearing and recheck clearance.
6. When replacing crankshaft or cylinder block due to any reason, select new standard bearings to be installed by referring to numerals stamped on new crankshaft or alphabets stamped on mating surface of new cylinder block.
^ Undersize Bearing (0.25 mm): 0.25 mm undersize bearing is available, in five kinds varying in thickness. To distinguish them, each bearing is painted in following colors at such position as indicated in figure. Each color represents following thicknesses at the center of bearing.
Color Painted: Green and Red
Bearing Thickness: 2.121 - 2.125 mm (0.0835 - 0.0836 inch)
Color Painted: Black and Red
Bearing Thickness: 2.124- 2.128 mm (0.0836 - 0.0837 inch)
Color Painted: Red only
Bearing Thickness: 2.127-2.131 mm (0.0837 - 0.0838 inch)
Color Painted: Yellow and Red
Bearing Thickness: 2.130 - 2.134 mm (0.0838 - 0.0839 inch)
Color Painted: Blue and Red
Bearing Thickness: 2.133 - 2.137 mm (0.0839 - 0.0840 inch)
^ If necessary, regrind crankshaft journal and select under size bearing to use with it as follows.
1. Regrind journal to following finished diameter.
Finished Diameter: 51.732 - 51.750 mm (2.0367 - 2.0373 inch)
2. Using micrometer, measure reground journal diameter. Measurement should be taken in two directions perpendicular to each other in order to check for out -of-round.
3. Using journal diameter measured above and alphabets stamped on mating surface of cylinder block, select an undersize bearing by referring to table given below. Check bearing clearance with newly selected undersize bearing.
Measured Journal Diameter: 51.744- 51.750 mm (2.0371 - 2.0373 inch)
Alphabets Stamped On Mating Surface Of Cylinder Block:
A (Green and Red)
B (Black and Red)
C (Red only)
Measured Journal Diameter: 51.738 - 51.744 mm (2.0369 - 2.0371 inch)
A (Black and Red)
B (Red only)
C (Yellow and Red)
Measured Journal Diameter: 51.732 - 51.738 mm (2.0367 - 2.0369 inch)
A (Red only )
B (Yellow and Red)
C (Blue and Red)
Undersize bearing to be installed.