Pistons and Connecting Rod
PISTON
COMPONENTS
CONNECTING ROD CAP
CAUTION: Keep the bearings in order with their corresponding connecting rods (according to cylinder numbers) for proper reassembly.
1. Remove the connecting rod cap bolts, then remove the caps and the big end lower bearing mark for reassembly.
2. Push each piston connecting rod assembly toward the top of the cylinder.
INSPECTION
PISTONS AND PISTON PINS
1. Check each piston for scuffing, scoring, wear and other defects. Replace any piston that is defective.
2. Check each piston ring for breakage, damage and abnormal wear. Replace the defective rings. When the piston requires replacement, its rings should also be replaced.
3. Check that the piston pin fits in the piston pin hole. Replace any piston and pin assembly that is defective. The piston pin must be pressed smoothly by hand into the pin hole (at room temperature).
PISTON RINGS
1. Measure the piston ring side clearance. If the measured value exceeds the service limit, insert a new ring in the ring groove to measure the side clearance. If the clearance still exceeds the service limit, replace the piston and rings together. If it is less than the service limit, replace only the piston rings.
Piston ring side clearance
No.1: 0.04 - 0.08 mm (0.0016 - 0.0031 inch)
No.2: 0.02 - 0.06 mm (0.0008 - 0.0024 inch)
2. To measure the piston ring end gap, insert a piston ring into the cylinder bore. Position the ring at right angles to the cylinder wall by gently pressing it down with a piston. Measure the gap with a feeler gauge. If the gap exceeds the service limit, replace the piston ring.
PISTON RING END GAP
Standard dimensions
No.1: 0.20 - 0.30 mm (0.0079 - 0.0118 inch)
No.2: 0.45 - 0.60 mm (0.0177 - 0.0236 inch)
Oil ring side rail: 0.2 - 0.7 mm (0.0079 - 0.0276 inch)
When replacing the ring without correcting the cylinder bore, check the gap with the ring situated at the lower part of cylinder that is less worn out.
PISTON RING SERVICE SIZE AND MARK
NOTE: The mark can be found on the upper side of the ring next to the end.
CONNECTING RODS
1. When the connecting rod cap is installed, make sure that the cylinder numbers, marked on rod end cap at disassembly, match. When a new connecting rod is installed, make sure that the notches holding the bearing in place are on the same side.
2. Replace the connecting rod if it is damaged at either end of the thrust faces. If it has a stratified wear, or if the surface of the inside diameter of the small end is severely rough, replace the rod.
REASSEMBLY
1. Install the spacer.
2. Install the upper side rail. To install the side rail, first put one end of the side rail between the piston ring groove and spacer, hold it firmly, and press down with finger on the portion to be inserted into the groove (as illustrated).
CAUTION: Do not use a piston ring expander when installing the side rail.
3. Install the lower side rail by the same procedure described in Step 2.
4. Apply engine oil around the piston and piston grooves.
5. Using a piston ring expander, install the No.2 piston ring.
6. Install the No. 1 piston ring.
7. Position each piston ring end gap as far away from its neighboring gaps as possible. Make sure that the gaps are not positioned in the thrust and pin directions.
8. Hold the piston rings firmly with a piston ring compressor as they are inserted into cylinder.
9. Install the upper connecting rod bearings in the connecting rod.
10. Install the lower connecting rod bearings in the connecting rod caps.
11. Make sure that the front mark of the piston and the front mark (identification mark) of the connecting rod are directed toward the front of the engine.
12. When the connecting rod cap is installed, make sure that any cylinder numbers placed on the rod and cap at disassembly match.
13. When a new connecting rod is installed, make sure that the notches for holding the bearing in place are on the same side.
14. When assembling, bolts should be fastened using the plastic angle technique as follows.
1) Apply oil to the threads and matching areas.
2) Tighten the connecting rod bolt.
Tightening torque
Connecting rod bolt: 34.3 Nm (3.5 kg-m, 25.3 ft. lbs.)+92°
CAUTION: After removing the connecting rod bolt, do not use it again. When using a new bolt, do not tighten the bolt more than 3 times.
15. Check the connecting rod side clearance.
Connecting rod side clearance
Standard: 0.10 - 0.25 mm (0.0039 - 0.0098 inch)
Limit: 0.4 mm (0.0157 inch)
REPLACEMENT
CONNECTING ROD BEARING (3.5)
1. Check the connecting rod big-end bore size code.
NOTE: Record the connecting rod big-end bore size code letters on connecting rod cap as shown.
CONNECTING ROD BIG-END DIAMETER
2. Check the crankshaft pin journal size code.
NOTE: Record the pin journal size code letters on the crankshaft balance weight. Reading order is from left to right as shown, with No. 1 pin journal size code shown first.
CRANKSHAFT PIN JOURNAL DIAMETER
3. Choose proper connecting rod bearing in below table.
CONNECTING ROD BEARING SELECTION TABLE
Connecting rod bearing oil clearance: 0.026 - 0.044 mm (0.0010 - 0.0017 inch)
CONNECTING ROD BEARING THICKNESS (REFERENCE DATA)