Pontiac tempest 1968 Service Manual page 242

SIX CYLINDER E N G I N E
6-25
Fig. 6-46 Removing Upper Rear Main O i l Seal
seal (Fig. 6-46) until it protrudes far enough to be
removed with pliers. Push new seal into place.
NOTE; Avoid scraping seal on edge of cap and
block seal locating grooves.
7. Install bearing cap using J 22325 (Fig. 6-44) and
torque bearing cap bolts 100 lb. ft.
8. Install oil pan. Do not overtighten.
MAIN BEARINGS-REMOVE AND REPLACE
The main bearings are of precision insert type and
do not utilize shims for adjustment. If the clear­
ances are found to be excessive, a new standard or
undersize bearing insert, both upper and lower
halves, will be required.
NOTE: To replace the upper half of the rear main
bearing, it will be necessary to loosen all main
bearing caps. Slowly rotate the crankshaft and
force bearing out with a putty knife or similar tool.
REMOVE
1. Remove oil pan. (See - "Oil Pan - Remove and
Replace".)
2. Remove cap on main bearing requiring replace­
ment and remove bearing from shell.
3. Install a main bearing shell removing and in­
stalling tool such as KMO 734 in the oil hole in the
crankshaft.
NOTE: If such a tool is not available, a cotter
pin may be bent as required to do the jo b (Fig.
6-47).
4. Rotate the crankshaft clockwise as viewed from
front of engine. This will roll upper bearing shell
out of engine.
R E P L A C E
1. Oil new upper bearing shell and insert plain
(unnotched) end of shell between crankshaft and in­
dented or notched side. Rotate the bearing into
place.
2. Install new bearing shell in bearing cap.
3. Check bearing clearance using Plastigage
method as outlined below.
4. Install oil pan using new gaskets and seals.
PLASTIGAGE METHOD OF DETERMINING
MAIN BEARING CLEARANCE
1. Place a .002" brass shim between the crank­
shaft journal and lower bearing in each bearing cap
next to that being checked. Tighten all cap bolts to
100 lb. ft. This causes the crankshaft to be forced
against the upper bearing and insures an accurate
measurement of total clearance.
2. Remove the bearing cap of bearing to be
checked. Wipe bearing and journal free of oil.
3. Place a piece of Plastigage, the length of bear­
ing (parallel to crankshaft), on journal or bearing
surface (Fig. 6-48). Install cap and tighten cap bolts
to proper torque.
NOTE: Do not turn crankshaft with Plastigage in
place.
4. Remove bearing cap and using Plastigage scale
on envelope measure width of compressed Plastigage
before removing it from the bearing or journal (Fig.
6-49). If bearing clearance is between .0003" and
.002", the clearance is satisfactory. If clearance is
more than .002", replace bearing with next under-
59°
Fig. 6 - 4 7 Tool For Removing Upper Half of Main Bearing