F
OR
M
ODELS
: JGI, JGM, JGN, JGP
AND
JGQ
S
ECTION
5 - M
AINTENANCE
PAGE 5-4
.
In the figure to the right, the throw on the left is in
its highest position and the throw on the right is in
its lowest position.
Inner Dead Center Position
Outer Dead Center Position
Highest and Lowest Throw Position
F
IGURE
5-2 T
HROW
P
OSITIONING
Connecting Rod
Connecting Rod (Crank Pin) Bearing
This bearing is a tri-metal (steel, bronze, and babbitt with a tin flash coat) precision split
(2-shell) bearing. There are notches in the rod and rod cap for the bearing tabs in order to
position and maintain the position of the bearing halves.
1.
Do not remove the connecting rod cap to check for bearing wear, if cap is
removed it is recommended that a new bearing is installed, i.e.
DO NOT REUSE
BEARING SHELLS
.
2.
Determine bearing wear by checking actual jack and side clearances against the
clearance limits given in Table 1-3 on page 1-10 and the last bearing clearance
check values, if available. High copper content in the oil analysis may be an indi-
cation of main and/or connecting rod bearing wear, and/or chain idler, cross-
head, connecting rod bushings wear (excessive use of anti-seize lubricates can
also elevate copper content in the oil analysis).
3.
After installing a new bearing(s), check jack and side clearances against the
clearance limits. Record values on a copy of from on Page 5-48.
4.
Use calibrated dial indicators with 0.0005 inches (0.005 mm) increments and
magnetic stands to check clearances.
5.
Check Jack clearance as follows:
a. As shown in Figure 5-3 on page 5-5, turn crankshaft pin up to the highest
throw position, install a magnetic stand on the top of adjacent crankshaft
web, with a needle type dial indicator placed against the top of the connect-
ing rod near the cap seam. Set indicator to zero.
