21
COMPILER TECO/ATI ENDORSEDDATE
23.06.2003
REG. CODE
1-5302-607
MODEL N°
50889
DATE OF ISSUE
06-03
REVISION 00
16
X
17
18
19
0,03 ÷ 0,06 0,15
0,05 ÷ 0,130 0,5
Ø 80 ÷ 80,020
Ø 85 ÷ 85,015
25LD330-2
25LD425-2
CHECKS AND OVERHAUL
Valves and springs
In order to check the springs for possible failure measure the
lengths under load as shown in figure 16.
The permissible tolerance for loads and lengths is ± 10%. If the
figures measured do not fall within these values, the springs must
be renewed.
Rocker arms
Make sure that the facing surfaces between rocker and pin are not
scored and show no signs of seizure. If such marks are
encountered, renew rocker and pin. Rocker / pin clearance (fig.17):
Make sure that the rocker arm adjusting screw is not worn and that
the lubrication hole is free of dirt.
Cylinders
Air cooled with cylinder barrels in special cast iron with integral
liners.
Use a dial gauge to check internal diameters (C-D) at three different
heights (fig.18).
Maximum permitted taper (A-B) and ovality (C-D) is 0.06mm.
Diameter of cylinders (fig.18):
If the diameter of the cylinder does not exceed said values or if there
are slight surface scores on the cylinder, it will be sufficient to
change the piston rings.
Do not manually hone the cylinder bore surfaces with
emery cloth or other means.
The cross-hatch pattern should be at an angle of 90°÷120°; lines
should be uniform and clear in both directions.
Average roughness must range between 0.5 mm 1 µm.
The cylinder surface which comes into contact with piston rings
should be machined with the plateau method.
If the taper and ovality of the cylinder exceed the values indicated,
then the cylinder and piston must be renewed.
Diameter of cylinders (fig.22):
Fitting mm Max. wear mm
Rocker axial play (fig.17):
Fitting mm Max. wear mm
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