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

•Inspection: Piston ring end gap
– Using the crown of a piston, push the piston ring horizontally into a cylinder in the crankcase until it reaches the lower part of the cylinder, where there is relatively small wear.
– Taking care not to move the piston ring, measure the end gap.
– If any of the rings has a gap exceeding the specified limit, replace all the piston rings as a set.

• Inspection: Piston ring side clearance in piston groove
– Remove any carbon deposits from the ring groove in the piston before measurement.
– Measure the side clearance of each ring around the piston’s entire periphery.
– The 1st compression ring is a full-keystone type. Measure the side clearance for this compression ring with a feeler gauge while pressing the ring against the piston with a straight edge.
– If any of the measurements exceeds the specified limit, replace the defective part(s). If any of the piston rings is defective, replace all the rings on the piston as a set.

• Inspection: Piston pin-to-piston clearance
– If any of the measurements exceeds the specified limit, replace the defective part(s).

•Inspection: Piston pin-to-connecting rod bushing clearance
– If any of the measurements exceeds the specified limit, replace the bushing.

Replacement of connecting rod bushing
• Replace the connecting rod bushing using
[Removal]
• Remove the upper rod bearing (if fitted) from the large end of the connecting rod.
• Mount the connecting rod on the base and lock it in position with the bracket and plate.
• Fit collar A over the puller with its ends facing in the illustrated directions. Then, slowly apply a pressure of approximately 49 kN {5000 kgf} to the puller with a press to force out the connecting rod bushing.

[Installation]
• Apply engine oil to the outside surface of the connecting rod bushing and the bushing fitting surface of the connecting rod.
• Fit collar B, the bushing, and collar A over the puller in the illustrated directions and lock this arrangement together with the nut.
• Align the oil holes in the connecting rod bushing and the connecting rod. Then, use a press to slowly apply a pressure of approximately 49 kN {5000 kgf} to the puller until the bushing is forced into place.
• After press-fitting the connecting rod bushing, measure the clearance between the piston pin and connecting rod bushing.
• If the measurement is less than the standard clearance range, ream the bushing.

Inspection: Connecting rod bend and twist
• Mount the connecting rod on the connecting rod aligner. Also mount the connecting rod bearings, piston pin, and connecting rod cap to create the same conditions as are expected when the connecting rod is mounted on a crankshaft. Tighten the nuts of the connecting rod bearing cap to a torque of 49 N·m {5 kgf· m}.
• Measure the extent of bend and twist in the connecting rod.
• If either measurement exceeds the specified limit, replace the connecting rod.

 

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