TM 5-3810-300-24-&P-3
1.6.1
Connecting Rod
Check the connecting rod for cracks (Fig. 12) by the
that the seal ring is free in the piston crown
magnetic particle method outlined in Section 1.3 under
groove. The seal ring-to-groove clearance is
Crankshaft Inspection.
.0005" to .0030".
Check the full 360
circumference of the groove to be sure there
If a new service connecting rod is required, stamp the
are no tight spots. When the piston crown,
cylinder number on the connecting rod and cap (refer to
seal ring and piston skirt are assembled, the
Section 1.6.3).
skirt should spin freely on the crown (crown
top down on the bench). If the seal ring sticks,
NOTE: Clean the rust preventive from a
remove high spots or nicks in the groove with
service replacement connecting rod and blow
a flat file. If this does not relieve sticking,
compressed air through the drilled oil passage
replace the piston crown.
to be sure it is clear of obstructions. Also
make sure the split line (cap to rod) is
4. Lubricate the piston pin with Cindol 1705 oil and
thoroughly cleaned
to
avoid
trapped
install it as shown in Fig. 14.
contaminants from adversely affecting bearing
CAUTION: Line up the piston pin opening in
shell "crush".
the piston skirt with the bearing (bushing)
Inspect the bearing (bushing) for indications of scoring,
opening in the piston crown to prevent damage
overheating or other damage. Measure the thickness of
to the pin or bushing.
the bushing along the center. Replace the bushing if it is
damaged or worn to a thickness of .086 " or less. A new
5. Install the spacers on the two 7/16"-20 x 2"
bushing is .087" to .088 " thick.
connecting rod to piston pin attaching bolts.
Inspect the piston pin for signs of fretting. When re-
6. Apply a small amount of International Compound No.
using a piston pin, the highly polished and lapped
2, or equivalent, to the bolt threads and bolt head contact
surface of the pin must not in any way be refinished.
surfaces.
Polishing or refinishing the piston pin is not
7. Install and tighten the bolts finger tight. Then clamp
recommended as it could result in very rapid bushing
the connecting rod in a -vise and tighten the bolts to 55-
wear. A new piston pin has a diameter of 1.4996" to
60 Ib-ft (75-81 Nm) torque (Fig. 15). Do not exceed this
1.5000". Replace the piston pin if it is worn to a diameter
of 1.4980 " or less.
8. Place a new piston pin retainer in position. Then
Assemble Connecting Rod to Piston
place the crowned end of installer J 23762 against the
retainer and strike the tool just hard enough to deflect the
1. Install the bearing (bushing) in the piston crown. It
retainer and seat it evenly in the piston (Fig. 16).
should slide into the piston crown without force. With
new parts, there is .0005 " to .0105 " clearance between
9. Install the second piston pin retainer in the same
the edge of the bushing and the groove in the piston
manner.
crown.
CAUTION: Due to the size of the counterbore
NOTE: The bearing must be installed before
in the piston skirt, be careful when installing
assembling the piston skirt and crown.
the piston pin retainers and inspect them to be
sure they are not buckled and that they are
2. Lubricate the metal seal ring (Fig. 13) with engine oil
fully seated in the counterbores. The width of
and install it with the chamfer or counterbore directed
the land should be even around the retainer.
toward the bottom of the piston.
10. Install the piston rings on the piston as outlined in
3. Compress the seal ring with ring compressor J
Section 1.6.
23453 and push the skirt into position on the piston
crown.
11. Install the piston and connecting rod assembly in the
engine as outlined in Section 1.6.3.
IMPORTANT: Before completely assembling
the piston, check to make sure the seal ring
does not stick in the ring groove.
It is
imperative for satisfactory engine operation
Page 99
