Connecting Rod: Testing and Inspection

INSPECTION

Connecting Rod





- Big-end side clearance: Check big-end of connecting rod for side clearance, with rod fitted and connected to its crank pin in the normal manner. If measured clearance is found to exceed its limit, replace connecting rod.
Big-End Side Clearance:
Standard: 0.25 - 0.40 mm (0.0099 - 0.0150 inch).
Limit: 0.40 mm (0.0157 inch).
- Connecting rod alignment: Mount connecting rod on aligner to check it for bow and twist. If limit is exceeded, replace it.
Limit On Bow: 0.05 mm (0.0020 inch).
Limit On Twist: 0.10 mm (0.0039 inch).

Crank Pin And Connecting Rod Bearings





- Inspect crank pin for uneven wear or damage. Measure crank pin for out-of-round or taper with a micrometer. If crankpin is damaged, or out-of-round or taper is out of limit, replace crankshaft or regrind crank pin to undersize and use undersize bearing.
Connecting Rod Bearing Size:
Standard:
Crank Pin Diameter: 49.982 - 50.000 mm (1.9678- 1.9685 inch).
0.25 mm (0.0098 in.) Undersize:
Crank Pin Diameter: 49.707 - 49.763 mm (1.9570 - 1.9591 inch).
Out-of-Round: A - B
Taper limit: a - b
Out-of-Round And Taper Limit: 0.01 mm (0.0004 inch).

Rod Bearing





Inspect bearing shells for signs of fusion, pitting, burn or flaking and observe contact pattern. Bearing shells found in defective condition must be replaced. Two kinds of rod bearing are available; standard size bearing and 0.25 mm (0.0098 inch) undersize bearing. For identification of undersize bearing, it is painted red at the position as indicated in figure, undersize bearing thickness is 1.605 - 1.615 mm (0.0632 - 0.0635 inch) at the center of it.

Rod Bearing Clearance
1. Before checking bearing clearance, clean bearing and crank pin.
2. Install bearing in connecting rod and bearing cap.





3. Place piece of gaging plastic the full width of crank pin as contacted by bearing (parallel to crankshaft), avoiding oil hole.





4. Install rod bearing cap to connecting rod. When installing cap, be sure to point arrow mark on cap to crankshaft pulley side, as shown in figure. After applying engine oil to rod bolts, tighten cap nuts to specified torque. DO NOT turn crankshaft with gaging plastic installed.
Tightening Torque (a): 45 N m (4.5 kg-m, 33.0 ft. lbs.).





5. Remove cap and using a scale on gaging plastic envelope, measure gaging plastic width at the widest point (clearance). If clearance exceeds its limit, use a new standard size bearing and remeasure clearance.
Bearing Clearance:
Standard: 0.045 - 0.063 mm (0.018 - 0.0024 inch)
Limit: 0.08 mm (0.0031 inch)
6. If clearance can not be brought to within its limit even by using a new standard size bearing, regrind crankpin to undersize and use 0.25 mm undersize bearing.

Selection Of Connecting Rod Bearing
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 crank pin diameter. There are numbers and alphabets stamped of crank web No.3 as shown in figure. Three alphabets ("A","B" and "C") represent following crank pin diameters.
Stamped Alphabet: A
Crank Pin Diameter: 49 994 - 50.000 mm (1.9683- 1.9685 inch)
Stamped Alphabet: B
Crank Pin Diameter: 49.988 - 49.994 mm (1.9680- 1.9682 inch)
Stamped Alphabet: C
Crank Pin Diameter: 49.982 - 49.988 mm (1.9678- 1.9680 inch)
2. Next check connecting rod bearing bore diameter without bearing. One of following number is stamped on the side of connecting rod big end. Three numbers ("1","2"and"3") represent following cap bore diameters.
Stamped Number: 1
Bearing Cap Bore Diameter (without Bearing): 53.000 - 53.006 mm (2.0866 - 2.0868 inch)
Stamped Number: 2
Bearing Cap Bore Diameter (without Bearing): 53.006 - 53.012 mm (2.0869 - 2.0870 inch)
Stamped Number: 3
Bearing Cap Bore Diameter (without Bearing): 53.012 - 53.018 mm (2.0871 - 2.0873 inch)





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: 1.482 - 1.485 mm (0.0584 - 0.0584 inch)
Color Painted: Black
Bearing Thickness: 1.485- 1.488 mm (0.0585 - 0.0585 inch)
Color Painted: Colorless (no paint)
Bearing Thickness: 1.488 - 1.491 mm (0.0586 - 0.0587 inch)
Color Painted: Yellow
Bearing Thickness: 1.491 - 1.494 mm (0.0587 - 0.0588 inch)
Color Painted: Blue
Bearing Thickness: 1.494- 1.497 mm (0.0588 - 0.0589 inch)
4. From alphabet stamped on crank web No.3 and the number stamped on connecting rod big end, determine new standard connecting rod bearing to be installed, by referring to table shown below. For example, if alphabet stamped on crank web No.3 is "B" and number stamped on connecting rod big end is "1", install a new standard bearing painted in "Black."
Alphabet Stamped On Crank Web (Crank Pin Diameter): A
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 1
Color: Green
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 2
Color: Black
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 3
Color: Colorless
Alphabet Stamped On Crank Web (Crank Pin Diameter): B
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 1
Color: Black
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 2
Color: Colorless
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 3
Color: Yellow
Alphabet Stamped On Crank Web (Crank Pin Diameter): C
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 1
Color: Colorless
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 2
Color: Yellow
Number Stamped On Big End (Connecting Rod Big End Bore Diameter): 3
Color: 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. If clearance can not be still brought to within its limit even by using a new standard size bearing, regrind the crank pin to undersize and use 0.25 mm undersize bearing.
Crank Pin Diameter (0.25 mm undersize): 49.707 - 49.763 mm 11.9570 - 1.9591 inch).
6. When replacing crankshaft or connecting rod due to any reason, select new standard bearings to be installed by referring to alphabet stamped on new crankshaft or number stamped on big end of new connecting rod.