Piston and Connecting Rods
Refer to the illustration for the removal procedure, noting the following:
1. Mark the cylinder number on the side of the connecting rod big end for correct reassembly.
2. Keep the removed connecting rods, caps, and bearings in order according to the cylinder number.
3. Service the piston pin. Service and Repair
4. Service the piston rings. Service and Repair
5. Liberally coat engine oil on the circumference of the piston, piston ring, and oil ring.
6. Arrange the piston ring and oil ring gaps (side rail and spacer) as shown in the figure.
7. Rotate crankshaft so that the crank pin is on center of cylinder bore.
8. Use suitable thread protectors on the connecting rod bolts before inserting piston and connecting rod assembly into the cylinder block. Care must be taken not to nick the crank pin.
9. Using a suitable piston ring compressor tool, install the piston and connecting rod assembly into the cylinder block.
10. When the connecting rod bearing needs replacing, select and install a proper bearing by the following procedure:
a. Measure the crankshaft pin diameter and confirm its classification from the following table. In the case of a crankshaft supplied as a service part, identification colors of its pins are painted at the positions shown in the illustration.
b. The connecting rod bearing identification mark is stamped at the position shown in the illustration.
Connecting rod inner diameter: 48.000 - 48.015 mm (1.8898 - 1.8903 inches)
c. Select a proper bearing from the above table on the basis of the identification data confirmed under Items (1) and (2)
Example:
If the measured value of a crankshaft pin outside diameter is between 44.995 and 45.000 mm (1.7715 and 1.7716 inches), the pin is classified as "1" in the table. If the crankshaft is replaced by a spare part, check the identification colors of the pins painted on the new crankshaft. If the color is yellow, for example, the pin is classified as "1." In the above cases, select the connecting rod bearing having identification mark "1."
11. Verifying the mark made on the connecting rod cap during disassembly, install the bearing cap to the connecting rod. If the connecting rod is new with no index mark, make sure that the bearing locking notches are on the same side as shown.
12. Make sure that the connecting rod big end side clearance meets the specification.
Standard value: 0.10 - 0.25 mm (0.004 - 0.009 inch)
Limit: 0.4 mm (0.015 inch)
13. Installation the connecting rod cap nut as follows:
NOTE: Installation of the connecting rod nut should be performed with the cylinder head or the spark plug removed.
a. Since the connecting rod bolts and nuts are torqued using the plastic area tightening method, the bolts should be examined before reuse. If the bolt threads are "necked down", the bolt should be replaced. Necking can be checked by hand threading the nut to the full length of the bolt threads. If the nut does not run down smoothly, the bolt should be replaced.
b. Before installation of each nut, apply engine oil to the threaded portion and bearing surface of the nut.
c. Loosely tighten each nut to the bolt.
d. Then tighten the nuts alternately to a torque of 20 Nm (14 ft. lbs.) to install the cap properly.
e. Make a paint mark on the head of each nut.
f. Make a paint mark on the bolt end at the position 90 - 100° from the paint mark made on the nut in the direction of tightening the nut.
CAUTION:
- If the nut is turned less than 90°, proper fastening performance may not be achieved. Be careful to tighten the nut exactly 90°.
- If the nut is overtightened (exceeding 100°), loosen the nut completely and then retighten it by repeating the tightening procedure from step 1.
g. Turn the nut 90 - 100° and make sure that the paint mark on the nut and on the bolt are aligned.