Note:
When the piston pin is installed, always install
new retaining rings on each end of the piston pin. If
the piston pin cannot be removed by hand, heat the
piston to a temperature of 45° ± 5 °C (113° ± 9 °F) in
order to aid the removal of the piston pin. Heating the
piston to this temperature may also aid the installation
of the piston pin.
Length of The Connecting Rod
The connecting rod length (CRL) is the length of the
connecting rod. Refer to Table 7 for each grade of
length of connecting rod.
In order to ensure that the piston height above the
cylinder block is correct, three grades of connecting
rods
“
R
”
to
“
B
”
are used during manufacture at the
factory. Replacement connecting rods are available in
three grades. These grades of connecting rod are
“
R
”
to
“
B
”
. The grade of length is identified by a letter or
a color which is marked on the side of the connecting
rod. The longest grade is marked with the letter
“
R
”
.
The shortest grade is marked with the letter
“
B
”
. The
difference in length between each grade of
connecting rods is the following value: 0.076 mm
(0.0030 inch)
The grade of length of a connecting rod is determined
in the factory by machining an eccentric hole in a
semi-finished piston pin bushing. Therefore, the
grade of length is determined by the position of the
center of the hole in the piston pin bearing.
If the connecting rod must be replaced, a new
connecting rod assembly must be purchased and
installed. Refer to Table 7 for more information.
A new piston pin bearing is installed in the new
connecting rod at the factory. The bore of the piston
pin bearing is reamed to the correct eccentricity.
Piston Pin Bearings
Note:
This procedure requires personnel with the
correct training and the use of specialized equipment
for machining.
If the piston pin bearing requires replacement but the
original connecting rod is not replaced, the following
procedures must be performed:
1.
Determine the grade of length of the connecting
rod. Use one of the following characteristics:
• The mark
• The color
• Measuring the length
2.
Ensure that the connecting rod is aligned parallel
and that the connecting rod is not distorted. Refer
to “Distortion of The Connecting Rod” in this
service module.
3.
Remove the piston pin bearing from the connecting
rod. Install a new bearing in the connecting rod.
The new bearing is partially finished. The new
bearing must be bored off-center to the correct
diameter. This off-center position is determined by
the grade of length of the connecting rod. Refer to
Table 7 . The correct diameter of the bore in the
piston pin bearing is given in Specifications,
“Connecting Rod”.
Surface finish of the bored hole in the piston pin
bearing .........................................Ra 0.8 micrometers
4.
Machine the ends of the piston pin bearing to the
correct length. Remove any sharp edges. Refer to
Specifications, “Connecting Rod”.
5.
If the grade of length of the connecting rod is
changed, the letter that is stamped on the
connecting rod must be removed. Etch a letter that
is for the new grade of length on the side of the
connecting rod.
Note:
Do not stamp a new letter on the connecting
rod. The force of stamping may damage the
connecting rod.
Table 7 references the following information: Grade
of letter of the connecting rod, the color code of the
connecting rods and the lengths of the connecting
rods.
Table 7
Length Grades for Connecting Rods
Grade Letter
Color Code
Length Of The Connect-
ing Rod (CRL)
R
Red
161.259 to 161.292 mm
(6.3488 to 6.3501 inch)
G
Green
161.183 to 161.216 mm
(6.3458 to 6.3471 inch)
B
Blue
161.107 to 161.140 mm
(6.3428 to 6.3441 inch)
Measure The Length Of The Connecting
Rod
If the mark or the color of the grade of length cannot
be observed on the connecting rod, perform the
following procedure:
42
UENR0617
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