Piston Ring: Service and Repair

PISTON RING





1. If piston ring is broken, damaged, or worn, or if its tension is insufficient, or when the piston is replaced, replace piston ring with a new one of the same size as the piston.

CAUTION:
^ Marks are shown on the end of the top and second rings. When installing the rings to the piston, face this mark upward.
^ Oil ring consists of upper rail, expander and lower rail. When installing on piston, be careful of each rail's direction.

2. Clean piston ring grove and piston ring.








3. Squarely place piston ring and oil ring in cylinder, and measure the piston ring gap with a thickness gauge.








4. Measure the clearance between piston ring and piston ring groove with a thickness gauge.

CONNECTING ROD
1. Replace connecting rod, if the large or small end thrust surface is damaged.





2. Check for bend or twist using a connecting rod aligner. Replace connecting rod if the bend or twist exceeds the limit.
Limit of bend or twist per 100 mm (3.94 inch) in length: 0.10 mm (0.0039 inch)





3. Install connecting rod fitted with bearing to crankshaft and measure the side clearance (thrust clearance). Replace connecting rod if the side clearance exceeds the specified limit.
Connecting rod side clearance:
Standard 0.070 - 0.330 mm (0.0028 - 0.0130 inch)
Limit 0.4 mm (0.016 inch)
4. Inspect connecting rod bearing for sear, peeling, seizure, melting, wear, etc.





5. Measure the oil clearance on individual connecting rod bearings by means of plastigauge. If any oil clearance is not within specification, replace the defective bearing with a new one of standard size or undersize as necessary.
Connecting rod oil clearance:
Standard 0.016 - 0.044 mm (0.0006 - 0.0017 inch)
Limit 0.050 mm (0.0020 inch)








6. Inspect bushing at connecting rod small end, and replace if worn or damaged. Also measure the piston pin clearance at the connecting rod small end.
Clearance between piston pin and bushing:
Standard 0 - 0.022 mm (0 - 0.0009 inch)
Limit 0.030 mm (0.0012 inch)





7. Replacement procedure is as follows.
1 Remove bushing from connecting rod with ST and press.
2 Press bushing with ST and press after applying oil on the periphery of bushing.
ST 499037100 CONNECTING ROD BUSHING REMOVER AND INSTALLER
3 Make two 3 mm (0.12 inch) holes in bushing. Ream the inside of bushing.
4 After completion of reaming, clean bushing to remove chips.