Dodge ram truck 3500 1996 Service Manual page 1013

B R
3.9L ENGINE 9 - 23
3.91 ENGINE
INDEX
page
page
GENERAL INFORMATION
OIL PUMP PRESSURE 23
PISTON AND CONNECTING ROD ASSEMBLY . . 23
VALVES AND VALVE SPRINGS 23
DESCRIPTION AND OPERATION
ENGINE COMPONENTS 26
ENGINE DESCRIPTION 23
ENGINE LUBRICATION SYSTEM 24
SERVICE PROCEDURES
CONNECTING ROD BEARINGS 28
CRANKSHAFT MAIN BEARINGS 29
CRANKSHAFT 29
FITTING PISTONS 27
FITTING RINGS 27
TIMING CHAIN STRETCH 27
VALVE TIMING 26
REMOVAL AND INSTALLATION
CAMSHAFT BEARINGS 39
CAMSHAFT 38
CRANKSHAFT MAIN BEARINGS 39
CRANKSHAFT REAR OIL SEALS 43
CRANKSHAFT 41
CYLINDER HEAD COMPONENTS—IN VEHICLE
SERVICE 32
CYLINDER HEAD COVER 32
CYLINDER HEADS 33
DISTRIBUTOR DRIVE SHAFT BUSHING 35
ENGINE ASSEMBLY 30
ENGINE CORE OIL AND CAMSHAFT PLUGS . . 45
ENGINE FRONT MOUNTS 29
ENGINE REAR MOUNT 30
FRONT CRANKSHAFT OIL SEAL 42
HYDRAULIC TAPPETS 34
OIL PAN 40
OIL PUMP 41
PISTON AND CONNECTING ROD ASSEMBLY . . 41
TIMING CHAIN COVER 36
TIMING CHAIN 38
VALVES AND VALVE SPRINGS—CYLINDER
HEAD REMOVED 34
VIBRATION DAMPER 36
DISASSEMBLY AND ASSEMBLY
CYLINDER BLOCK 48
HYDRAULIC TAPPETS 45
OIL PUMP 48
VALVES, GUIDES AND SPRINGS 46
CLEANING AND INSPECTION
CRANKSHAFT INSPECTION OF JOURNALS . . . 49
CYLINDER BLOCK 51
CYLINDER HEAD COVER 48
CYLINDER HEAD 48
OIL PAN 51
OIL PUMP 49
PISTON AND CONNECTING ROD INSPECTION . 49
SPECIFICATIONS
ENGINE SPECIFICATIONS 52
SPECIAL TOOLS
3.9L ENGINE 56
G E N E R A L I N F O R M A T I O N
VALVES AND VALVE SPRINGS
The valves are arranged in-line and are inclined
18°. The rocker pivot support and the valve guides
are cast integral with the heads.
OIL PUMP PRESSURE
The MINIMUM oil pump pressure is 41.4 kPa (6
psi) at curb idle. The MAXIMUM oil pump pressure
is 207-552 kPa (30-80 psi) at 3,000 RPM or more.
CAUTION: If oil pressure is ZERO at curb idle, DO
NOT run engine at 3,000 RPM.
PISTON AND CONNECTING ROD ASSEMBLY
The pistons are elliptically turned so that the
diameter at the pin boss is less than its diameter
across the thrust face. This allows for expansion
under normal operating conditions. Under operating
temperatures, expansion forces the pin bosses away
from each other, causing the piston to assume a more
nearly round shape.
All pistons are machined to the same weight,
regardless of size, to maintain piston balance.
The piston pin rotates in the piston only and is
retained by the press interference fit of the piston
pin in the connecting rod.
D E S C R I P T I O N A N D O P E R A T I O N
ENGINE DESCRIPTION
The 3.9 Liter (238 CID) six-cylinder engine is a
V-Type, lightweight, single cam, overhead valve
engine with hydraulic roller tappets (Fig. 1).
This engine is designed to use unleaded fuel.