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3-50 ENGINE
PISTON RING-TO-GROOVE CLEARANCE
• Measure the side clearances of the 1st and 2nd piston rings
using the thickness gauge.
• If any of the clearances exceeds the limit, replace both the
piston and piston rings.
09900-20803: Thickness gauge
09900-20205: Micrometer (0 – 25 mm)
Piston ring-to-groove clearance:
Service Limit (1st) : 0.180 mm (0.0071 in)
(2nd) : 0.150 mm (0.0059 in)
Piston ring groove width:
Standard (1st) : 1.01 – 1.03 mm (0.0398 – 0.0406 in)
(2nd) : 0.81 – 0.83 mm (0.0319 – 0.0327 in)
(Oil) : 1.51 – 1.53 mm (0.0594 – 0.0602 in)
Piston ring thickness:
Standard (1st) : 0.97 – 0.99 mm (0.0382 – 0.0390 in)
(2nd) : 0.77 – 0.79 mm (0.0303 – 0.0311 in)
PISTON RING FREE END GAP AND PISTON RING END GAP
• Measure the piston ring free end gap using the vernier cali-
pers.
• Next, fit the piston ring squarely into the cylinder and measure
the piston ring end gap using the thickness gauge.
• If any of the measurements exceeds the service limit, replace
the piston ring with a new one.
Piston ring free end gap:
Service Limit (1st) : 4.4 mm (0.17 in)
(2nd) : 6.8 mm (0.27 in)
09900-20102: Vernier calipers
Piston ring end gap:
Service Limit (1st) : 0.50 mm (0.020 in)
(2nd) : 0.50 mm (0.020 in)
09900-20803: Thickness gauge