Rear Main Bearing Oil Seal (Crankshaft) - Jeep 1979 CJ-5 Technical & Service Manual

ENGINES 1B-31
cylinder block replacement or machining to true bore. If
journal size is less than 2.4981 inch (63.4517 mm), re-
place crankshaft or grind to accept suitable undersize
bearing.
Measuring Main Bearing Journal with Micrometer (Crankshaft Removed)
(1) Clean main bearing journal.
(2) Measure maximum diameter of journal with mi-
crometer. Take two readings 90° apart at each end of
journal.
(3) Compare reading obtained with journal diame-
ters listed in Main Bearing Fitting Chart and select
inserts required to obtain specified bearing clearance.
Installation
(1) Lubricate bearing surface of each insert with
clean engine oil.
(2) Loosen all main bearing caps and install main
bearing upper insert(s).
(3) Install main bearing cap(s) and lower insert(s).
Tighten screws to 40 foot-pounds (54 N*m) torque. Then
tighten to 60 foot-pounds (81 N*m). Finally, tighten to 80
foot-pounds (108 N»m). Rotate crank after tightening
each main cap to make sure crankshaft rotates freely.
NOTE: When installing a crankshaft kit (crankshaft
plus bearing inserts), check each bearing for fit, using
Plastigage.
(4) Install oil pan, using replacement gaskets and
seals. Tighten drain plug.
(5) Fill crankcase with clean oil to specified dipstick
level.
Rear l a i n Bearing Oil Seal
The rear main bearing crankshaft oil seal consists of
two pieces of neoprene with a single lip that effectively
seals the rear of the crankshaft. To ensure leak-free
operation, replace the upper and lower seal halves in
pairs.
Removal
(1) Drain engine oil.
(2) Remove oil pan.
(3) Remove rear main bearing cap and discard
lower seal.
(4) Loosen all remaining bearing capscrews.
(5) Use brass drift and hammer to tap upper seal
until seal protrudes enough to permit pulling it out
completely.
(6) Remove oil pan front and rear neoprene oil seals
and oil pan side gaskets.
(7) Clean gasket surfaces of oil pan and engine
block. Remove all sludge and dirt from oil pan sump.
(8) Clean main bearing cap thoroughly to remove
all sealer.
Installation
(1) Wipe seal surface of crankshaft clean and
lightly coat with engine oil.
(2) Coat lip of seal with engine oil.
(3) Install upper seal into engine block.
NOTE: Lip of seal must face toward front of engine.
(4) Coat both sides of lower seal end tabs with RTV
silicone (Jeep Gasket-in-a-Tube, or equivalent), being
careful to not apply sealer to lip of seal.
(5) Coat outer curved surface of lower seal with
soap and lip of seal with engine oil.
(6) Install seal into cap recess and seat it firmly.
(7) Coat both chamfered edges of rear main bearing
cap with RTV silicone (fig. 1B-55).
CAUTION: Do not apply sealer to cylinder block mat-
ing surfaces of rear main bearing cap as bearing clear-
ance would be affected.
(8) Install rear main bearing cap.
(9) Tighten all main bearing capscrews to 80 foot-
pounds (108 N®m) torque.
(10) Install oil pan using replacement gaskets and
seals. Tighten drain plug.
(11) Fill crankcase with clean oil to specified dipstick
level.
L I Q U I D
Fig. 1B-55 Rear Main Oil Seal and Cap Installation
Vibration Damper
The vibration damper is balanced independently and
then rebalanced as part of the complete crankshaft
assembly.