Chevrolet 1988 Light Duty Truck Repair Manual page 374

6A1-22 2.5 LITER L4 ENGINE
• M ount the crankshaft in V-blocks or between
centers.
• Use a dial indicator as shown.
• If the main bearing journals are misaligned,
the crankshaft is bent and must be replaced
along with the main bearings.
PRIOR TO ASSEMBLY
The importance of cleanliness during the assembly
p ro ce d u re c a n n o t be o v e rstre sse d . D irt w ill cause
prem ature wear of the rebuilt engine.
Lubricate all moving parts lightly with engine oil or
engine assem bly lubricant (unless specified otherwise)
during assembly. This will provide initial lubrication when
the engine is started.
CRANKSHAFT AND MAIN
BEARING INSTALLATION
Service bearing inserts are available in standard size
and 0.001-inch undersize.
Install or C o n n e c t (F ig u re s 5 and 39)
1. Upper main bearing inserts (86 and 72) to the block.
• If any previously used or undersized bearings
are used, make absolutely certain that they
are fitted to the proper journal.
2. Crankshaft (88). Take care not to dam age the thrust
areas.
3. Lower bearing inserts (86 and 72) to the bearing
caps.
M easu re
Main bearing clearance. Refer to GENERAL
E N G IN E M E C H A N IC A L (SEC. 6A) in this
manual.
3. Engine oil to the lower main bearing inserts.
ASSEMBLY OF ENGINE
Figure 38 — Checking Crankshaft Runout
4. Main bearing caps (except the rear cap) with the
selected lower main bering inserts (86 and 72). Be
sure to put the main bearing cap in their original
positions, with the arrows facing the front of the
engine.
5. Bolts (125). Make sure the special bolt, w hich
retains the oil pum p pickup tube and screen is
installed in the proper position. (#4 main bearing
cap, cam shaft side hole.)
T ig h ten
• Main bearing cap bolts to 95 N m (70 ft. lbs.).
6. Rear main bearing cap to the block.
7. Rear main bearing cap bolts. Tighten the bolts
tem porarily to 14 N m (10 ft. lbs.).
M easu re (F ig u re 40)
• Crankshaft end play, as follows:
• Tap the end of the crankshaft first rearward
then forward with a lead hammer. This will line
up the rear main bearing and crankshaft thrust
surfaces.
• Tighten the rear main bearing cap bolts to 95
N m (70 ft. lbs.).
• W ith the crankshaft forced forward, measure
at the front end of the rear main bearing with a
feeler gage. The proper clearance is 0.09 -
0.20 mm (0.0035 - 0.0085-inch).
I?
In sp ect
Crankshaft for binding. Try turning the crankshaft to
check for binding. If the crankshaft does not turn
freely, loosen the main bearing cap bolts, one pair at
a time, until the tight bearing is located. Burrs on the