F
OR
M
ODELS
: JGI, JGM, JGN, JGP
AND
JGQ
S
ECTION
5 - M
AINTENANCE
PAGE 5-23
same time. (For JGI models, slide crankshaft into position through the bearing
carrier opening and then replace bearing carrier).
2.
When the crankshaft is resting on the bearing saddles, install all bearing caps
with their new bearing half shells. Bearing caps are match-marked to corre-
spond with the throw position on the frame, be sure they are in the proper loca-
tions. Lubricate the bearing cap bolting threads and seating surfaces with oil and
instal lightly snugged.
3.
Be sure the dowels in the bearing caps are aligned with the holes in the crank-
case base. A set screw on top of each dowel prevents it from backing out.
4.
Then, starting at the thrust end, tighten the bolts in an alternating (criss-cross)
pattern in 25% increments to the recommended torque value in Table 1-12 on
page 1-16.
5.
Check crankshaft journal bearing jack (at each bearing) and crankshaft thrust
clearances to values in Table 1-3 on page 1-10. See "Main Bearings - Checking
Clearances" on Page 5-14. Record readings on a copy of the form on
Page 5-48.
6.
Replace connecting rods bearings and re-attach the connecting rods refer to
“Connecting Rod - Installation” on page 1-8). Re-install the packing diaphragms,
piston and rod, and unloaders/head end heads, if removed.
7.
Re-install the force feed lubricator and chain drive. (See “Chain Drive System”
on page 5-23).
8.
Examine the top cover gasket. If there is any doubt that it is not in good usable
condition, install a new gasket. Before installing a gasket, apply an antiseize
lubricant to both sides or to the metal seating surfaces. This will help to hold the
gasket in place during assembly and aid in easy of removal.
9.
Re-install covers, crankshaft seal housing and the top cover. Tighten cap screws
hand wrench tight. Align crankshaft dust seal to clearance requirements in Table
1-3 on page 1-10.
Chain Drive System
Description
The chain drive system is crankshaft-driven at the auxiliary end of the frame. The chain runs
the lube oil pump and force feed lubricator. Chain tightness is controlled by an idler sprocket
attached to the eccentric adjustment cap. The chain dips into the crankcase oil and, as a
