FUSO 4M4 – Engine – PISTON AND CONNECTING ROD – Installation procedure

Installation: Connecting rod bolts
• Check that there are no burrs or other defects on the surface of the connecting rod bolt holes. Replace the connecting rod if defects are evident.
• Apply engine oil to the knurled surface of the connecting rod bolt. Then, install the bolt by using a press to apply a pressure of approximately 4.9 kN {500 kgf} at the maximum with the cuts of the bolt head facing in the illustrated direction.

Installation: Piston and connecting rod
• Install pistons and connecting rods as follows when replacing them.
• All the cylinders used in the same engine must be the same in weight.
• If the cylinder has not been machined to an oversize, check that the size marks of piston and upper crankcase (“A”, “B” or “C”) are the same. The piston size for each cylinder is shown on the upper crankcase.

• Apply engine oil to the piston pin, and assemble the piston and connecting rod with their marks facing in the illustrated directions.
• If the piston is difficult to insert, heat the piston in hot water or with a piston heater.

Installation: Piston rings
• With the manufacturer’s mark (found near the piston ring end gaps) facing up, install the piston rings so that the end gap of each ring is positioned as illustrated.
A: 1st compression ring end gap
B: 2nd compression ring end gap
C: Oil ring end gap
D: Oil ring’s expander spring end gap
“O”: Front mark on piston
The manufacturer’s marks are present only on the 1st and 2nd compression rings.

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