Connecting Rods

Cleaning

Remove the connecting rod bearings (6211) from the connecting rod (6200) and connecting rod cap. Identify each connecting rod bearing location if they are to be used again. Clean the connecting rod in solvent, including the rod bore and the back of the bearing inserts. Do not use a caustic cleaning solution. Blow out all passages with compressed air.

Inspection

1. Measure the inside diameter of the connecting rod bushing (6207) using a telescoping gauge and a micrometer. If connecting rod bushings are out of specification, new connecting rod bushings must be installed.

   

2. Remove any worn connecting rod bushing using Piston Pin Remover/Replacer T68P-6135-A.

3. Place the connecting rod under a hydraulic press in line with the properly sized hole on the support block and use Piston Pin Remover/Replacer T68P-6135-A to press out the connecting rod bushing.

   

4. Clean the connecting rod thoroughly and visually inspect for defects.

5. Using a telescoping gauge and a micrometer, check the connecting rod bushing bore diameter.

   

6. NOTE: Measure connecting rod bearing bore diameter with connecting rod nut tightened to specified torque.

   Inspect the crankshaft end of the connecting rod as follows:

   1. Measure connecting rod bearing bore diameter.
      
      

   2. With the connecting rod bolt (6214) assembled and connecting rod bolts and connecting rod nuts (6212) tightened to specification, use a dial bore gauge indicator to measure out-of-round. Replace connecting rod if maximum out-of-round specification is exceeded. Refer to Specifications at the end of this section.
      
      

   3. Measure the connecting rod bore taper by measuring the bore inside diameter near the large chamfer. Record reading and measure the bore inside diameter near the small chamfer; record reading. The difference between the two readings is the bore taper. Replace connecting rod if maximum bore taper is exceeded.
      
      

   4. With the connecting rod cap removed, visually inspect the surface finish of the connecting rod bearing bore. The connecting rod bearing bore must be smooth and free of scoring or nicks.
      
      

7. An engine component wear pattern can be identified and used to diagnose a problem. Following are common examples of connecting rod wear pattern diagnostic hints.

   • A shiny surface on the edge of the connecting rod bushing usually indicates that a connecting rod is bent or a piston pin hole is not in proper relation to piston skirt and ring grooves.
   • Abnormal connecting rod bearing wear can be caused by either a bent connecting rod, an improperly machined journal, or a tapered connecting rod bore.
   • Twisted connecting rods will not create an easily identifiable wear pattern, but badly twisted connecting rods will disturb the action of the entire piston, piston rings, and connecting rod and may be the cause of excessive oil consumption.

8. Install a new connecting rod bushing using Piston Pin Remover/Replacer T68P-6135-A as follows:

   1. Place the new connecting rod bushing on Piston Pin Remover/Replacer T68P-6135-A and lubricate the connecting rod bushing outside diameter with clean engine oil.
   2. Place the connecting rod on a flat surface plate with the large chamfer side of the main bearing bore up.
   3. Press the new connecting rod bushing in place flush or below the surfaces of both sides of the connecting rod.
      
      

9. After the connecting rod bushing has been installed in the connecting rod, it must be honed to the proper inside diameter. Refer to Specifications at the end of this section.

   

10. NOTE: The connecting rod end clearance must be checked to be certain that the specified clearance exists. Lack of clearance could indicate a damaged connecting rod or a connecting rod bearing out of position. Correct as required. Excessive clearance may require replacement of the crankshafts (6303) or crankshaft.

    Check the connecting rod side clearance, using a feeler gauge.