GMC 1989 Light Duty Truck Repair Manual page 426

6A3-2 4.3 LITER V-6
SUBJECT
Assembly of Engine (Continued)
Front Cover Installation........................................................................................................................................................ 6A 3 -1 8
Torsional Damper Installation.............................................................................................................................................6A 3 -1 8
Piston and Connecting Rod In s ta lla tio n .........................................................................................................................6A 3 -2 0
Oil Pump Installation .............................................................................................................................................................6A3-21
Oil Pan Installation................................................................................................................................................................. 6A3-21
Cylinder Head Installation....................................................................................................................................................6A3-21
Valve Train Component Installation..................................................................................................................................6A 3-23
Valve Adjustm ent....................................................................................................................................................................6A 3-23
Intake Manifold Installation..................................................................................................................................................6A 3-23
Rocker Arm Cover In s ta lla tio n ...........................................................................................................................................6A 3-23
Exhaust Manifold In s ta lla tio n ............................................................................................................................................. 6A 3 -2 3
EGR Valve Installation................................................................................................................................. ........................ 6A 3 -2 4
Flywheel In s ta lla tio n ............................................................................................................................................................. 6A 3-24
Engine Accessory In s ta lla tio n .................................. i ......................................................................................................6A 3-24
Engine Set-Up and T e s tin g ................................................................................................................................................. 6A 3 -2 5
S p e c ific a tio n s .............................................................................................................................................................................6 A 3 -2 7
Special T o o ls ............................................................................................................................................................................... 6 A 3 -3 0
GM 4.3L engines are 90-degree V6 type, overhead
valve, water cooled, with cast iron block and heads.
The crankshaft is supported by four precision insert
main bearings, with crankshaft thrust taken at the number
four (rear) bearing.
The camshaft is supported by four plain type bearings
and is chain driven. Motion from the camshaft is transm it­
ted to the valves by hydraulic lifters, pushrods, and ball
type rocker arms. The valve guides are integral in the cyl­
inder head.
The connecting rods are forged steel, with precision in­
sert type crankpin bearings. The piston pins are a press fit
in the connecting rods.
The pistons are cast aluminum alloy. The piston pins
are a floating fit in the piston.
For identification, refer to GENERAL INFORMATION
(SEC. OB).
CONTENTS
DESCRIPTION
Lubrication schematics are shown in figures 1 and 2.
The gear type oil pump is driven from the distributor
shaft, which is gear driven from the camshaft. Oil is drawn
into the oil pump through a pickup screen and pipe.
Pressurized oil is routed to the oil filter. In case of
excessive oil pressure, a bypass valve is provided.
Filtered oil flows into the main gallery and then to the
camshaft and crankshaft bearings. The valve lifter oil
gallery supplies oil to the valve lifters. Oil flows from the
hydraulic lifters through the hollow pushrods to the rocker
arms. Oil from the overhead drains back to the crankcase
through oil drain holes.
The tim ing chain is drip fed from the front camshaft
bearing. The pistons and piston pins are lubricated by oil
splash.
ENGINE LUBRICATION
PAGE