Connecting Rod: Service and Repair

REMOVAL
1. Remove top ridge of cylinder bores with a reliable ridge reamer before removing pistons from cylinder block. Be sure to keep tops of pistons covered during this operation. Pistons and connecting rods must be removed from top of cylinder block. When removing piston and connecting rod assemblies from the engine, rotate crankshaft so that each connecting rod is centered in cylinder bore.

Figure 93-Identify Connecting Rod To Cylinder:

2. Inspect connecting rods and connecting rod caps for cylinder identification. Identify them if necessary.

Figure Connecting Rod Guides And Crankshaft Protectors:

3. Remove connecting rod cap. Install protectors on connecting rod bolts. Push each piston and rod assembly out of cylinder bore.

NOTE: Be careful not to nick crankshaft journals.

4. After removal, install bearing cap on the mating rod.

PISTON RINGS-INSTALLATION

Figure 95 Piston Ring - Installation:

1. The No. 1 and No. 2 piston rings have a different cross section. Insure that the No. 2 ring is installed with manufacturers I.D. mark (dot) facing up, towards top of the piston.

CAUTION: Install piston rings in the following order:

2. Oil ring expander.
3. Upper oil ring side rail.
4. Lower oil ring side rail.
5. No. 2 Intermediate piston ring.
6. No. 1 Upper piston ring.

Figure 96 Side Rail - Installation:

7. Install the side rail by placing one end between the piston ring groove and the expander. Hold end firmly and press down the portion to be installed until side rail is in position. Do not use a piston ring expander during this step.
8. Install upper side rail first and then the lower side rail.

Figure 97 Upper And Intermediate Rings - Installation:

9. Install No. 2 piston ring and then No. 1 piston ring.

Figure 98-Piston Ring End Gap Position:

10. Position piston ring end gaps.
11. Position oil ring expander gap at least 46° from the side rail gaps but not on the piston pin center or on the thrust direction. Staggering ring gap is important for oil control.

PISTON-INSTALLATION

NOTE: The connecting rod bearing cap bolts must be examined before reuse. If the threads are necked down, the bolts should be replaced.

Figure 99 Check For Stretched Bolts:

1. Check connecting rod bolts for necking by holding a scale or straight edge against the threads. If all threads do not contact the scale, the bolt should be replaced.
2. Before installing pistons and connecting rod assemblies into the bore, ensure that compression ring gaps are staggered so that neither is in line with oil ring rail gap.

Figure 100 Piston - Installation:

3. Before installing the ring compressor, make sure the oil ring expander ends are butted and the rail gaps.
4. Immerse the piston head and rings in clean engine oil, slide the ring compressor over the piston and tighten with the special wrench. Ensure position of rings does not change during this operation.
5. Install connecting rod bolt protectors on rod bolts.
6. Rotate crankshaft so that the connecting rod journal is on the center of the cylinder bore. Insert rod and piston into cylinder bore and guide rod over the crankshaft journal.

CAUTION: Do Not interchange piston assemblies bank to bank.

Figure 101 Piston Orientation:

Figure 102-Connecting Rod Positioning:

7. The arrow on top of piston must be pointing toward front of engine and oil squirt hole on connecting rod faces the major thrust (right) side of the cylinder bore.
8. Tap the piston down in cylinder bore, using a hammer handle. At the same time, guide connecting rod into position on connecting rod journal.
9. Install rod caps. Install nuts on cleaned and oiled rod bolts and tighten nuts to 54 Nm (40 ft. lbs.) Plus 1/4 turn.