Piston and Connecting Rod
Piston and Connecting Rod
Piston, Connecting Rod and Associate Parts
Disassembly
1. Remove cylinder head assembly (1).
2. Remove cylinder head gasket (2).
3. Remove oil pan assembly and oil pan support (4).
4. Remove oil strainer.
5. Remove balance unit assembly.
6. Remove connecting rod cap with connecting rod lower bearing.
7. Remove piston and connecting rod assembly.
Note: Before removing piston and connecting rod assembly, measure thrust clearance.
^ Remove any ridge or carbon build up from the top end of the cylinder.
8. Remove the piston rings with a piston ring expander. (1) Arrange the removed piston rings in the cylinder number order.
Note: Keep the parts removed from each cylinder separate. All parts must be reinstalled in their original positions.
Inspection and Repair
Pistons
Carefully clean away all the carbon adhering to the piston head and the piston ring grooves.
Note: Never use a wire brush to clean the pistons. Damage will result Visually check each piston for cracking, scoring, and other signs of excessive wear. If any of the above conditions are found, the piston must be replaced.
Piston Rings
Any worn or damaged part discovered during engine overhaul must be replaced with a new one.
1. Ring end gap measurement
^ Insert the piston ring into the bore.
^ Push the ring by the piston, at a right angle to the wall, into the point at which the cylinder bore diameter is the smallest.
^ Measure the ring end gap.
2. Measure the clearance between the piston ring groove and the piston ring with a feeler gauge. If the piston ring groove / piston ring clearance exceeds the specified limit, the piston must be replaced.
Compression Ring Clearance (1st and 2nd) 0.02 mm - 0.04 mm (0.0008 inch - 0.0016 inch)
Oil Ring Clearance: 0.01 mm - 0.03 mm (0.0004 inch - 0.0012 inch)
Piston Pin
Note: Do not reuse the old piston pin.
1. Use a micrometer to measure the new piston pin outside diameter in both directions at three different positions.
Standard diameter: 21 mm (0.8268 inch)
2. Install the new piston pin.
Coat connecting rod boss and upper part of connecting rod stem with thermo-color pencil.
When the required assembly temperature is attained, green color turns black. The colored line (arrow) must not change colors over the entire length, but only up to the start of the connecting rod stem. Heart upper connecting rod boss of new connecting.
Assembly temperature: 280 to maximum 320°C (536 to maximum 608°F).
Connecting Rod Bearings Clearance
1. Measure the oil clearance between the connecting rod and the crankshaft.
1. Remove the connecting rod cap bolts and the rod caps.
Arrange the removed rod caps in the cylinder number order.
2. Clean the rod bearings and the crankshaft pins.
3. Carefully check the rod bearings. If even one bearing is found to be damaged or badly worn, the entire bearing assembly must be replaced as a set. Reinstall the bearings in their original positions. Apply plastigage to the crank pin.
4. Reinstall the rod caps to their original positions.
Tighten the rod cap nuts.
1st step: 35 Nm (26 ft. lbs.)
2nd step: 45°
Note: Do not allow the crankshaft to rotate.
5. Remove the rod caps.
Reassembly
1. Install connecting rod
2. Install piston
3. Install piston pin.
Note: When changing piston / connecting rod combinations, do not change the piston /piston pin combination and do not reuse the old piston pin.
4. Install piston ring with the piston ring expander.
^ New piston rings with "Top" upper most use commercially available pliers.
^ Position ring gaps:
1- Compression rings 180° to each other as illustrated (A).
2- Offset oil control rings (B) or (B) 25 to 50 mm (1 to 2 inch) from gap of second compression ring.
^ After installation, apply engine oil to the entire circumference of the piston rings. Check to see that all the rings rotate smoothly.
5. Install piston and connecting rod assembly.
^ Insert the bearings into the connecting rods and caps. Apply new engine oil to the bearing faces and bolts.
^ Tighten the connecting rod cap bolts in 2 steps:
1st step: 35 Nm (26 ft. lbs.)
2nd step: 45°
Note: Do not apply engine oil to the bearing back faces.
6. Install balance unit assembly.
7. Install balance unit assembly.
8. Oil strainer and O-ring.
9. Install oil pan support assembly.
10. Install cylinder head gasket.
11. Install cylinder head assembly.