Connecting Rod Bearing: Service and Repair
CONNECTING ROD BEARING - FITTINGFit all rods on one bank until complete. Do not alternate from one bank to another, because when the rods are assembled to pistons correctly, they are not interchangeable from one bank to another.
The bearing caps are not interchangeable and should be marked at removal to insure correct assembly.
The bearing shells must be installed so that the tangs are in the machined grooves in the rods and cars.
Limits of taper or out-of-round on any crankshaft journals should be held to 0.013 mm (0.0005 inch). Bearings are available in 0.025 mm (0.001 inch), 0.051 mm (0.002 inch), 0.076 mm (0.003 inch), 0.254 mm (0.010 inch) and 0.305 mm (0.012 inch) undersize. Install the bearings in pairs. Do not use a new bearing half with an old bearing hale Do not file the rods or bearing caps.
1. Measuring Connecting Rod Bearing Clearance to determine bearing clearance (Fig. 90).
2. Before installing the connecting rod cap nuts, the bolt threads should be oiled with engine oil.
3. Install nuts on each bolt finger tight, then alternately torque each nut to assemble the cap properly.
4. Tighten the connecting rod nuts to 85 Nm (62.5 ft. lbs.).
MEASURING CONNECTING ROD SIDE CLEARANCE
1. Using a feeler gauge, check connecting rod side clearance (Fig. 91).
MEASURING CONNECTING ROD BEARING CLEARANCE
Engine crankshaft bearing clearances can be determined by use of Plastigage or equivalent. The following is the recommended procedure for the use of Plastigage:
1. Rotate the crankshaft until the connecting rod to be checked is at the bottom of its stroke.
2. Remove oil film from surface to be checked. Plastigage is soluble in oil.
3. Place a piece of Plastigage across the entire width of the bearing shell in the bearing cap approximately 6.35 mm (1/4 inch) off center and away from the oil hole (Fig. 100). In addition, suspect areas can be checked by placing Plastigage in the suspect area.
4. Before assembling the rod cap with Plastigage in place, the crankshaft must be rotated until the connecting rod being checked starts moving toward the top of the engine. Only then should the cap be assembled and torqued to specifications. Do not rotate the crankshaft while assembling the cap or the Plastigage may be smeared, giving inaccurate results.
5. Remove the bearing cap and compare the width of the flattened Plastigage (Fig. 101) with the metric scale provided on the package. Locate the band closest to the same width. This band shows the amount of clearance in thousandths of a millimeter. Differences in readings between the ends indicate the amount of taper present. Record all readings taken. Plastigage generally is accompanied by two scales. One scale is in inches, the other is a metric scale.
6. Plastigage is available in a variety of clearance ranges. The 0.025 - 0.076 mm (0.001 - 0.003 inch) is usually the most appropriate for checking engine bearing proper specifications.