1993 DODGE TRUCK Service Repair Manual

9
- 12
ENGINES

•
CONDITION

POSSIBLE
CAUSES
CORRECTION

EXCESSIVE
EXHAUST

SMOKE
(Cont'd)
More
than
one
sealing washer
under an injector.
Check
and remove
extra
washer.
Improperly operating injectors.
Check
and replace inoperative injectors.
Improperly operating or over-
fueled injection pump.
Replace
injection pump.

Piston
rings
not sealing
(blue smoke). Perform blow-by check. Correct as required.

ENGINE
WILL
NOT

SHUT-OFF
Fuel shutoff valve inoperative.

Engine
running on fumes drawn into the air intake.
Stop
the engine mechanically
with
lever on the
fuel
pump.

Check/replace
sealing washer, piston and
spring.

Check
the air intake ducts for the source of the fumes.
WARNING:
In
ease
of engine runaway due to flammable
fumes

from gasoline spills or turbocharger oil leaks
being
sucked
into the
engine,
shut off engine ignition switch first then use a CO* or dry
chemical type
fire
extinguisher
and direct the
spray
under
the
front
bumper to
remove
oxygen
supply. The engine air
intake
is on the

passenger
side
behind the bumper. The
fire
extinguisher
must
bo
directed at this location for emergency shutdown conditions.

COOLANT
TEMPERA­

TURE
ABOVE
NORMAL
Low
coolant level.
(a) Check coolant level. Add coolant, if necessary.
(b) Locate and correct the source of the coolant leak. Refer to
troubleshooting
logic for coolant
loss.

Incorrect/improperly operating

pressure
cap.
Replace
cap
with
the correct rating for the
system.

High
lube oil level.
Check/drain
oil to correct level.

Loose
drive belt on water

pump/fan.
Check/replace
belt or belt tensioner.
Inadequate air flow to the radiator. Check/repair radiator core, fan shroud and fan clutch as
required.

Radiator
fins
plugged.
Blow
debris from fins.

Collapsed
radiator
hose.
Replace
the
hose.

Improperly operating tempera­

ture
sensor/gauge.
Verify
that
the
gauge
and temperature
sensor
are accurate.

Replace
gauge/sensor,
if bad.
Improperly operating, incorrect

or
no thermostat.
Check
and replace the thermostat.

Air
in the cooling
system.
(a) Make sure the
fill
rate
is not being exceeded and the correct
vented thermostat is installed.
(b) Check for loose hose
clamps.
Tighten if
loose.

(c) If aeration continued, check for a
compression
leak through the head gasket.
Inoperative water pump.
Check
and replace the water pump.
incorrect injection pump timing. Verify pump timing marks are aligned. Check/time the injector

pump
(refer
to Group 7,
Cooling
System).
J9209-56
SERVICE DIAGNOSIS (DIESEL ENGINE) - PERFORMANCE (CONT.)

•

ENGINES
9 - 13

CONDITION
POSSIBLE
CAUSES
COfiiiECTION

COOLANT
TEMPERA­

TURE
ABOVE
NORMAL
(Cont'd)
Overfueled injection pump.

Plugged
cooling
passages
in
radiator, head, head gasket or

block.

Engine
overloaded.
Replace
the injection
pump.

Flush
the
system
and
fill
with
clean coolant.
Verify
that
the engine load rating is not being exceeded.

COOLANT
TEMPERA­

TURE
BELOW
NORMAL
Too
much air flow
across
the
radiator.
Incorrect thermostat, broken
thermostat jiggle pin or

contamination
in thermostat.
Temperature
sensor
or
gauge
inoperative.

Coolant
not flowing by
temperature
sensor.
Check/repair
viscous
fan as required.

Check
and replace thermostat.
Verify
that
the
gauge
and
sensor
are accurate. If not, replace

gauge/sensor.

Check
and clean coolant
passages.

J9109-254
SERVICE DIAGNOSIS (DIESEL ENGINE) • PERFORMANCE (CONT.)

9
- 14
ENGINES
— — — •

SERVICE
DIAGNOSIS (DIESEL ENGINE)
•
MECHANICAL

CONDITION

r— ———
POSSIBLE
CAUSES
CORRECTION

LUBRICATING
OIL

PRESSURE
LOW Low oil
level.

(a)
Check
and
fill
with
clean engine oil.
(b) Check for a severe
external
oil leak
that
could reduce the pressure.
Oil viscosity thin,
diluted
or wrong specification.
Verify
the correct oil is being
used.
Check for oil dilution. Refer
to Contaminated Lube Oil (Engine Diagnosis—Mechanical).
Improperly operating pressure

switch/gauge.
Verify
the pressure switch is functioning correctly. If not,
replace switch/gauge.
Relief valve stuck open. Check/replace valve.

Plugged
oil
filter.
Change
oil
filter.
Oil
filter
change
interval
may need to be
revised.
If cooler was replaced, shipping

plugs
left
in cooler. Check/remove shipping
plugs.

If pump replaced, four cylinder
oil pump installed in a six
cylinder engine.
Verify
that
the correct pump is installed. If not, install an oil
pump for a six cylinder engine.

Loose
or
missing
cup
plugs.
Check and replace cup
plugs.

Worn oil pump. Check and replace oil pump.

Suction
tube
loose or seal leaking. Check and replace seal.

Loose
main bearing cap. Check and
install
new bearings and tighten cap to proper torque.
Worn bearings or wrong bearings installed. inspect and replace connecting rod or main bearings. Check and
replace piston cooling nozzles.

J9109-237

•
• —
ENGINES
9 - 15
CONDITION

POSSIBLE CAUSES
CORRECTION

LUBRICATING
OIL

PRESSURE
TOO
HIGH
Pressure
switch/gauge
not

operating
properly.
Verify
the
pressure
switch
is
functioning
correctly.
If not,

replace
switch/gauge.

Engine
running
too
cold.
Refer
to
Coolant
Temperature
Below
Normal
(Engine
Diagnosis-

Performance)

Oil
viscosity
too thick. Make
sure
the
correct
oil Is
being
used.
Refer
to
Group
O,

Lubrication
and
Maintenance.

Oil
pressure
regulator
valve

stuck
closed
or
binding.
Check
and replace valve, and/or oil cooler cover.

LUBRICATING
OIL
LOSS
External
leaks.
Visually
inspect for oil
leaks.
Repair as required.

Crankcase
being
overfilled. Verify that the correct dipstick is being
used.

incorrect
oil specification or

viscosity.
(a) Make sure the correct oil is being
used.

(b)
Look
for reduced
viscosity
from dilution with fuel.
(c) Review/reduce the oil
change
intervals.
Oil
cooler
leak.
Check
and replace the oil cooler.

High
blow-by
forcing oil out
the breather.
Check
the breather tube area for
signs
of oil
loss.
Perform the
required repairs.

Turbocharger
leaking
oil to the
air intake.
Inspect
the air
ducts
for evidence of oil transfer.

Repair
as required.

Worn
valve
seals.
Inspect
and replace the valve
seals.

Piston
rings
not
sealing
(oil

being
consumed
by the
engine).
Perform
blow-by check. Repair as required.

COMPRESSION
KNOCKS
Air in the
fuel
system.

Poor
quality
fuel.
Bleed
the fuel
system
(refer
to
Group
14, Fuel
System).

Verify by operating from a temporary tank with
good
fuel. Clean

and
flush the fuel
supply
tanks.
Replace fuel/water separator

filter.

Engine
overloaded. Verify that engine load rating is not being exceeded.
Incorrect injection
pump
timing.
Check
and time injection pump
(refer
to
Group
14, Fuel
System).

Improperly
operating
injectors.
Check
and replace inoperative injectors. J9109-266 SERVICE DIAGNOSIS (DIESEL ENGINE) - MECHANICAL (CONT.)

9 - 16
ENGINES

•
CONDITION

POSSIBLE
CAUSES
CORRECTION

EXCESSIVE
VIBRATION
Loose
or broken engine mounts.
Replace
engine mounts.

Damaged
fan or improperly
operating
accessories.
Check
and replace the vibrating components.
Improperly operating vibration
clamper. Inspect/replace the vibration damper.
Improperly operating fan hub. Inspect/replace the fan hub.

Worn
or
damaged
alternator
bearing.
Check/replace
the alternator.
Flywheel
housing
misaligned. Check/correct flywheel alignment.

Loose
or broken power

component.
Inspect
the crankshaft and rods for damage
that
causes
an

unbalance.
Repair/replace as required.

Worn
or unbalanced driveline
components.
Check/repair driveline components.

EXCESSIVE
ENGINE

NOISES
Drive belt squeal, insufficient

tension
or abnormally high
loading.
Check
the tensioner and inspect the drive belt. Make sure water

pump,
tensioner pulley, fan hub and alternator turn
freely.

Intake air or exhaust leaks. Refer to
Excessive
Exhaust
Smoke
(Engine
Diagnosis—

Performance).

Excessive
valve
lash
Adjust
valves.
Make sure the
push
rods are not bent and rocker
levers or adjusting screws are not severely worn. Replace bent

or
severely worn
pads.

Turbocharger
noise.
Check
turbocharger impeller and turbine wheel for housing
contact. Repair/replace as required.

Gear
train
noise.
Visually
inspect and measure gear
backlash.
Replace gears as
required.

Power
function knock.
Check/replace
rod and main bearings.

ALTERNATOR
NOT

CHARGING
OR IN-
SUFFICIENT
CHARGING
Loose
or corroded battery

connections.

Alternator belt slipping. Clean/tighten battery connection.

Check/replace
belt tensioner. Check/replace belt.
Alternator pulley loose on
shaft.
Tighten pulley.
Improperly operating
alternator.
Check/replace
alternator.
J9109-253
SERVICE DIAGNOSIS (DIESEL ENGINE) - MECHANICAL (CONT.)

•

3.9L ENGINE
9 - 17
3.9L
ENGINE SERVICE PROCEDURES
INDEX

page

Camshaft
31

Crankshaft
38

Crankshaft Main Bearings
39

Crankshaft Rear
Oil
Seals
. 40

Cylinder Block
41
Cylinder Head Cover
. , 21

Cylinder Heads
. 22
Distributor
33

Engine
Assembly .........................
20

Engine
Front Mounts
17

Engine
Rear Mount
18

Front Crankshaft
Oil
Seal Replacement ........
31

GENERAL INFORMATION
The 3.9 Liter (238 CID) six-cylinder engine is a
V-Type, lightweight, single cam, overhead valve en­ gine with hydraulic roller tappets (Fig. 1).

Engine
Type
90° V-6 OHV

Bore
and Stroke 99.3
x
84.0 mm (3.91 x3.31
in.)

Displacement 3.9L (238 cu.
in.)

Compression
Ratio
9.1:1

Torque 305 N-m (225
ft.
lbs.)
@
3,200
rpm
Firing Order.... 1-6-5-4-3-2

Lubrication
Pressure
Feed-Full Flow
Filtration

Engine
Oil
Capacity 3.8L (4.0 Qts)
with Filter

Cooling
System
Liquid Cooled-Forced
Circulation

Cooling Capacity 14.3L
(15.1
Qts)

Cylinder Block Cast Iron
Crankshaft Nodular Iron
Cylinder Head
Cast
Iron
Combustion Chambers "Fast
Burn"
Design
Camshaft Nodular
Cast
Iron

Pistons
Aluminum Alloy
w/Strut

Connecting
Rods
Forged Steel

J9309-29

Fig.
1
Engine
Description
This engine is designed for unleaded fuel. Engine lubrication system consists of a rotor type
oil pump and a full flow oil filter.
The cylinders are numbered from front to rear; 1,

3,
5 on the left bank and 2, 4, 6 on the right bank.
The firing order is
1-6-5-4-3-2
(Fig. 2).
The engine serial number is stamped into a ma­
chined pad located on the left, front corner of the cyl­
inder block. When component part replacement is
necessary, use the engine type and serial number for
reference (Fig. 3).
page

General
Information
17
Hydraulic Tappets
27

Oil
Pan 34

Oil Pump
34

Piston
/
Connecting
Rod
Assembly
36
Rocker
Arms
21

Specifications—3.9L Engine
43

Timing Chain Cover
29

Valve Stem Seal
/
Spring Replacement ........
27

Valve Timing
28

Valves
/
Valve Springs
25
Vibration
Damper
29
J9309-26
Fig.
2 Firing Order i M 3.9L T xxxx
XXXXXXXX

X
=
Last Digit
of
Model Year
M
=
Plant -
M
Mound
Road

S
Sabillo
T Trenton
K
Toluca

3.9L
=
Engine Displacement
T
=
Usage
-
T Truck

XXXX
=
Month/Day

XXXXXXXX
- Serial Code -
Last
8
Digits of
VIN
No.

J9209-72

Fig.
3
Engine
identification
Number

ENGINE FRONT MOUNTS

REMOVAL (1) Disconnect the negative cable from the battery.

9
- 18 3.9L
ENGINE

• (2) Raise hood and position fan to assure clearance
for radiator top tank and hose.

CAUTION:
DO NOT
lift
the engine by the
intake
manifold.

(3) Install engine lifting fixture.
(4) Raise vehicle on hoist.
(5) Remove bolts and nuts from insulators (Figs. 4
and 5).
ATTACHING

BOLT
ATTACHING

NUT
BRACKET

INSULATOR

ATTACHING
BOLT
FRAME
SIDE

INSULATOR?
(RIGHT
SIDE)
(LEFT
SIDE)

J9109-238

Fig.
4
Engine
Front
Mounts—2WD
Vehicles
ATTACHING
NUT

FRAME
SIDE
INSULATOR

BRACKET

STUD
NUT»

STUD NUT

ATTACHING
BOLT INSULATOR

BACKING.

PLATE
ATTACHING
NUT
BRACKET

STUD NUT

FRONT

BRACKET

STUD NUT

ATTACHING
NUT

FRAME
s,de
(RIGHT
SIDE)
J9109-239

Fig.
5
Engine
Front
Mounts—4WD
Vehicles
(6) Raise engine with lifting fixture only far
enough to remove insulators.
(7) If necessary, remove the bracket from the block

(Figs.
4 and 5).
(8) If necessary, remove the front bracket (4WD)
from the crossmember (Fig. 5).
INSTALLATION (1) If removed, position the front bracket (4WD) to
the crossmember (Fig. 5). Install the attaching nuts and tighten to 41 N»m (30 ft. lbs.) torque. (2) If removed, position the bracket to the block

(Figs.
4 and 5). Install the bolts and tighten to 41
N*m (30 ft. lbs.) torque. (3) With engine raised SLIGHTLY, install insula­
tors on front bracket (Figs. 4 and 5).
(4) Lower engine with lifting fixture while guiding
insulator studs into brackets.
(5) Install attaching bolts and nuts (Figs. 4 and 5).
Tighten the attaching bolts and nuts to 41 N«m (30 ft. lbs.) torque,
(6) Install insulator stud nuts and washers.
Tighten the stud nuts to 102 N»m (75 ft. lbs.) torque.
(7) Lower the vehicle.
(8) Remove lifting fixture.
ENGINE
REAR
MOUNT
REMOVAL-2WD (1) Raise the vehicle on a hoist. (2) Position a transmission jack in place.
(3) Remove rear mount insulator through-bolt and
nut (Fig. 6). (4) Raise rear of transmission and engine

SLIGHTLY.
(5) Remove the flange nuts from the frame cross-
member support bracket (Fig. 6). (6) Raise rear of transmission enough to provide
insulator to crossmember clearance. Remove the in­ sulator and the crossmember support bracket. Re­
move the flange nuts and separate the insulator from
the support bracket (Fig. 6).
(7) If necessary, remove the attaching bolts hold­
ing the transmission support bracket to the transmis­
sion (Fig. 6).
INSTALLA
TION-2WD
(1) If removed, position the transmission support
bracket to the transmission. Install the attaching
bolts and tighten to 68 N*m (50 ft. lbs.) torque.
(2) Position insulator in transmission support
bracket. Install through-bolt.
(3) Be sure insulator is secured in a LEVEL posi­
tion relative to transmission rear support bracket.
Tighten the through-bolt nut to 68 N*m (50 ft. lbs.) torque.
(4) Position the crossmember support bracket onto
the insulator (Fig. 6). Install the insulator flange nut(s) and tighten to 41 Nnn (30 ft. lbs.) torque.
(5) Using the transmission jack, lower the insula­
tor and crossmember support bracket onto the cross- member (Fig. 6).
(6) Tighten the crossmember flange nuts to 41 Nnn
(30 ft. lbs.) torque.
(7) Remove the transmission jack.
(8) Lower the vehicle.
HE MO
VAL—4
WD (1) Raise the vehicle on a hoist.

3.9L
ENGINE
9 - 19

INSULATOR
TRANSMISSION

ATTACHING
BOLT
TRANSMISSION

THROUGH
BOLT

TRANSMISSION

SUPPORT
BRACKET

INSULATOR
CROSSMEMBER

SUPPORT BRACKET

CROSSMEMBER

FLANGE NUTS TRANSMISSION

SUPPORT
BRACKET
A
ATTACHING
§^ BOLT
J9109-241
(2) Remove the skid plate (if equipped) from the
rear crossmember and transmission crossmember (Fig. 7). (3) Position transmission jack under transmission
and raise rear
of
transmission and engine
SLIGHTLY.
(4)
AUTOMATIC
TRANSMISSION—Remove
the nuts and bolts holding the transmission support spacer to the insulator mounting plate (Fig. 8). Re­
move the bolts and nuts holding the engine rear sup­
port plate to the insulator mounting plate (Fig. 8).

(5)
MANUAL
TRANSMISSION—Remove the
nuts and bolts holding the insulator mounting plate
to the transfer case (Fig. 9).
(6) Remove insulator mounting bolts, spacers,
washers and upper/lower insulators (Figs. 8 and 9).
Fig.
6 Rear
Engine
Support—2WD
(7) Remove the insulator mounting plate (Figs. 8
and 9).

TRANSFER CASE
ENGINE
REAR

SUPPORT
PLATE EXTENSION
ASSEMBLY

TRANSMISSION
SUPPORT
SPACER
^——SPACER
fjy.^
UPPER ^INSULATOR
INSULATOR
MOUNTING PLATE
LOWER
INSULATOR

RAIL
ASSEMBLY
J9109-243

PU873
Fig.
8 Rear
Engine
Support—4WD
with
Automatic

Transmission

Fig.
7
Skid
Plate