ENGINE 18
233
312168-10
– Measure the piston at the piston skirt, at right angles to the
piston pin, at a distance
B
.
Guideline
Distance
B
50 mm (1.97 in)
Piston - diameter (All 250 models)
Size I 66.340 … 66.350 mm
(2.61181 … 2.6122 in)
Size II 66.351 … 66.360 mm
(2.61224 … 2.61259 in)
Piston - diameter (All 300 models)
Size I 71.940 … 71.950 mm
(2.83228 … 2.83267 in)
Size II 71.951 … 71.960 mm
(2.83271 … 2.83307 in)
Info
Piston dimensions
1
are marked on the piston head.
18.5.14 Checking the piston ring end gap
D04519-10
– Remove the piston ring from the piston.
– Place the piston ring in the cylinder and align with the piston.
Guideline
Below the upper edge of the
cylinder
20 mm (0.79 in)
–
Measure end gap
A
with a feeler gauge.
Guideline
Piston ring - end gap
Ring 1 ≤ 0.40 mm (≤ 0.0157 in)
Ring 2 ≤ 0.40 mm (≤ 0.0157 in)
» If the end gap is greater than the specified value:
– Check/measure the cylinder. ( p. 224)
» If cylinder wear lies within the specified tolerance:
– Change the piston ring.
– Mount the piston ring with the marking facing toward the pis-
ton head.
18.5.15 Measuring the piston/cylinder mounting clearance
D04518-10
– Check/measure the cylinder. ( p. 224)
– Check/measure the piston. ( p. 232)
– The smallest piston/cylinder mounting clearance equals the
smallest cylinder bore diameter minus the largest piston diam-
eter. The largest piston/cylinder mounting clearance equals the
largest cylinder bore diameter minus the smallest piston diam-
eter.
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