1998 DODGE RAM 1500 Over drive

CRANKSHAFT OIL SEAL - FRONT
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(3) Remove A/C compressor mouning fasteners and
set aside.
(4) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(5) Remove upper radiator hose.
(6) Disconnect electrical connector for fan mounted
inside radiator shroud.
(7) Remove radiator shroud attaching fasteners.
NOTE: Transmission cooler line snaps into shroud
lower right hand corner.
(8)
Remove radiator cooling fan and shroud (Refer to
7 - COOLING/ENGINE/RADIATOR FAN - REMOVAL).
(9) Remove crankshaft damper bolt.
(10) Remove damper using Special Tools 8513
Insert and 1026 Three Jaw Puller (Fig. 37).
(11) Using Special Tool 8511, remove crankshaft
front seal (Fig. 38).
INSTALLATION
CAUTION: To prevent severe damage to the Crank-
shaft, Damper or Special Tool 8512, thoroughlyclean the damper bore and the crankshaft nose
before installing Damper.
(1) Using Special Tool 8348 and 8512, install
crankshaft front seal (Fig. 39).
(2) Install vibration damper (Refer to 9 - ENGINE/
ENGINE BLOCK/VIBRATION DAMPER - INSTAL-
LATION).
Fig. 37 Crankshaft Damper Removal
1 - SPECIAL TOOL 8513 INSERT
2 - SPECIAL TOOL 1026
Fig. 39 Crankshaft Front Seal Installation
1 - TIMING CHAIN COVER
2 - SPECIAL TOOL 8348
3 - SPECIAL TOOL 8512
Fig. 38 Crankshaft Front Seal Removal
1 - SPECIAL TOOL 8511
9 - 46 ENGINE - 3.7LDR

(3) Install radiator cooling fan and shroud (Refer
to 7 - COOLING/ENGINE/RADIATOR FAN -
INSTALLATION).
(4) Install upper radiator hose.
(5) Install A/C compressor and tighten fasteners to
54 N´m (40 ft. lbs.).
(6) Install accessory drive belt refer (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(7) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(8) Connect negative cable to battery.
CRANKSHAFT OIL SEAL -
REAR
REMOVAL
NOTE: This procedure can be performed in vehicle.
(1) If being preformed in vehicle, remove the
transmission.
(2) Remove the flexplate (Refer to 9 - ENGINE/
ENGINE BLOCK/FLEX PLATE - REMOVAL).
NOTE: The crankshaft oil seal CAN NOT be reused
after removal.
NOTE: The crankshaft rear oil seal remover Special
Tool 8506 must be installed deeply into the seal.
Continue to tighten the removal tool into the seal
until the tool can not be turned farther. Failure to
install tool correctly the first time will cause tool to
pull free of seal without removing seal from engine.
(3) Using Special Tool 8506 (Fig. 40), remove the
crankshaft rear oil seal.
INSTALLATION
(1) Lubricate the crankshaft flange with engine oil.
(2) Position the magnetic seal guide Special Tool
8349-2 (Fig. 41) onto the crankshaft rear face. Then
position the crankshaft rear oil seal onto the guide.
Fig. 40 Crankshaft Rear Oil Seal Removal
1 - REAR CRANKSHAFT SEAL
2 - SPECIAL TOOL 8506
Fig. 41 Crankshaft Rear Oil Seal Guide Special Tool
8349-2 and Oil
1 - REAR CRANKSHAFT SEAL
2 - SPECIAL TOOL 8349-2 GUIDE
DRENGINE - 3.7L 9 - 47
CRANKSHAFT OIL SEAL - FRONT (Continued)

(5) Install fan blade assembly (Refer to 7 - COOL-
ING/ENGINE/FAN DRIVE VISCOUS CLUTCH -
INSTALLATION).
(6) Install radiator upper shroud and tighten fas-
teners to 11 N´m (95 in. lbs.).
(7) Connect electrical connector for shroud fan.
(8) Install radiator upper hose.
(9) Install accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTAL-
LATION).
(10) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(11) Connect negative cable to battery.
STRUCTURAL COVER
DESCRIPTION
The structural dust cover is made of die cast alu-
minum and joins the lower half of the transmission
bell housing to the engine bedplate.
OPERATION
The structural cover provides additional power-
train stiffness and reduces noise and vibration.
REMOVAL
(1) Raise vehicle on hoist.
(2) Remove the left hand exhaust pipe from
exhaust manifold.
(3) Loosen the right hand exhaust manifold-to-ex-
haust pipe retaining bolts.
(4) Remove the eight bolts retaining structural
cover (Fig. 64) in the sequence shown.
(5) Pivot the exhaust pipe downward and remove
the structural cover.
INSTALLATION
CAUTION: The structural cover must be installed as
described in the following steps. Failure to do so
will cause severe damage to the cover.
(1) Position the structural cover in the vehicle.
(2) Install all four bolts retaining the cover-to-en-
gine. DO NOT tighten the bolts at this time.
(3) Install the four cover-to-transmission bolts. Do
NOT tighten at this time.
CAUTION: The structural cover must be held tightly
against both the engine and the transmission bell
housing during tightening sequence. Failure to do
so may cause damage to the cover.(4) Starting with the two rear cover-to-engine
bolts, tighten bolts (1) (Fig. 65) to 54 N´m (40 ft. lbs.),
then tighten bolts (2) (Fig. 65) and (3) to 54 N´m ( 40
ft. lbs.) in the sequence shown.
(5) Install the exhaust pipe on left hand exhaust
manifold.
(6) Tighten exhaust manifold-to-exhaust pipe
retaining bolts to 20±26 N´m (15±20 ft. lbs.).
Fig. 64 Structural Cover
1 - BOLT
2 - BOLT
3 - BOLT
Fig. 65 Structural Cover
1 - BOLT
2 - BOLT
3 - BOLT
DRENGINE - 3.7L 9 - 57
VIBRATION DAMPER (Continued)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE OIL LEAK
Begin with a thorough visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24 km (15 miles), and
repeat inspection.If the oil leak source is not posi-
tively identified at this time, proceed with the air
leak detection test method.
Air Leak Detection Test Method
(1) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(2) Remove the PCV valve from the cylinder head
cover. Cap or plug the PCV valve grommet.
(3) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kPa (3 PSI) of test pressure.
(4) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service manual
procedures.
(5) If the leakage occurs at the rear oil seal area,
refer to the section, Inspection for Rear Seal Area
Leak.
(6) If no leaks are detected, turn off the air supply
and remove the air hose and all plugs and caps.
Install the PCV valve and breather cap hose.(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the
engine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak:
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, distributor seal,
camshaft bore cup plugs oil galley pipe plugs, oil
filter runoff, and main bearing cap to cylinder
block mating surfaces.
(4) If no leaks are detected, pressurize the crank-
case as outlined in the, Inspection (Engine oil Leaks
in general)
CAUTION: Do not exceed 20.6 kPa (3 psi).
(5) If the leak is not detected, very slowly turn the
crankshaft and watch for leakage. If a leak is
detected between the crankshaft and seal while
slowly turning the crankshaft, it is possible the
crankshaft seal surface is damaged. The seal area on
the crankshaft could have minor nicks or scratches
that can be polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft
polishing is necessary to remove minor nicks and
scratches. The crankshaft seal flange is especially
machined to complement the function of the rear oil
seal.
(6) For bubbles that remain steady with shaft
rotation, no further inspection can be done until dis-
assembled.
9 - 64 ENGINE - 3.7LDR
LUBRICATION (Continued)

(3) Remove the timing chains and tensioners
(Refer to 9 - ENGINE/VALVE TIMING/TIMING
BELT/CHAIN AND SPROCKETS - REMOVAL).
(4) Remove the four bolts, primary timing chain
tensioner and the oil pump.
DISASSEMBLY
(1) Remove oil pump cover screws and lift off cover
plate.
(2) Remove pump inner and outer rotors.
NOTE: Once the oil pressure relief valve, cup plug,
and pin are removed, the pump assembly must be
replaced.
(3) If it is necessary to remove the pressure relief
valve, drive the roll pin from pump housing and
remove cup plug, spring and valve.
INSPECTION
CAUTION: Oil pump pressure relief valve and spring
should not be removed from the oil pump. If these com-
ponents are disassembled and or removed from the
pump the entire oil pump assembly must be replaced.
(1) Clean all parts thoroughly. Mating surface of
the oil pump housing should be smooth. If the pump
cover is scratched or grooved the oil pump assembly
should be replaced.
(2) Lay a straight edge across the pump cover sur-
face (Fig. 76). If a 0.025 mm (0.001 in.) feeler gauge
can be inserted between the cover and the straight
edge the oil pump assembly should be replaced.(3) Measure the thickness of the outer rotor (Fig.
77). If the outer rotor thickness measures at 12.005
mm (0.472 in.) or less the oil pump assembly must be
replaced.
(4) Measure the diameter of the outer rotor. If the
outer rotor diameter measures at 85.925 mm (3.382
in.) or less the oil pump assembly must be replaced.
(5) Measure the thickness of the inner rotor (Fig.
78). If the inner rotor thickness measures at 12.005
mm (0.472 in.) or less then the oil pump assembly
must be replaced.
Fig. 76 Checking Oil Pump Cover Flatness
1 - STRAIGHT EDGE
2 - FEELER GAUGE
3 - OIL PUMP COVER
Fig. 77 Measuring Outer Rotor Thickness
Fig. 78 Measuring Inner Rotor Thickness
9 - 68 ENGINE - 3.7LDR
OIL PUMP (Continued)

block. A large washer on the idler shaft bolt and the
rear flange of the idler shaft are used to control
sprocket thrust movement. Pressurized oil is routed
through the center of the idler shaft to provide lubri-
cation for the two bushings used in the idler sprocket
assembly.
There are two secondary drive chains, both are
roller type, one to drive the camshaft in each SOHC
cylinder head. There are no shaft speed changes in
the secondary chain drive system. Each secondary
chain drives a 26 tooth cam sprocket directly from
the 26 tooth sprocket on the idler sprocket assembly.
A fixed chain guide and a hydraulic oil damped ten-
sioner are used to maintain tension in each second-
ary chain system. The hydraulic tensioners for the
secondary chain systems are fed pressurized oil from
oil reservoir pockets in the block. Each tensioner
incorporates a controlled leak path through a device
known as a vent disc located in the nose of the piston
to manage chain loads. Each tensioner also has a
mechanical ratchet system that limits chain slack if
the tensioner piston bleeds down after engine shut
down. The tensioner arms and guides also utilize
nylon wear faces for low friction and long wear. The
secondary timing chains receive lubrication from a
small orifice in the tensioners. This orifice is pro-
tected from clogging by a fine mesh screen which is
located on the back of the hydraulic tensioners.
STANDARD PROCEDURE
MEASURING TIMING CHAIN WEAR
NOTE: This procedure must be performed with the
timing chain cover removed.
(1) Remove the timing chain cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT/CHAIN
AND SPROCKETS - REMOVAL).
(2) To determine if the secondary timing chains
are worn, rotate the engine clockwise until maximum
tensioner piston extension is obtained. Measure the
distance between the secondary timing chain ten-
sioner housing and the step ledge on the piston. The
measurement at point (A) must be less than 15mm
(.5906 inches) (Fig. 95).
(3) If the measurement exceeds the specification
the secondary timing chains are worn and require
replacement (Refer to 9 - ENGINE/VALVE TIMING/
TIMING BELT/CHAIN AND SPROCKETS -
REMOVAL).
SERVICE PROCEDURE - TIMING VERIFICATION
CAUTION: The 3.7L is a non free-wheeling design
engine. Therefore, correct engine timing is critical.
NOTE: Components referred to as left hand or right
hand are as viewed from the drivers position inside
the vehicle.
NOTE: The blue link plates on the chains and the
dots on the camshaft drive sprockets may not line
up during the timing verification procedure. The
blue link plates are lined up with the sprocket dots
only when re-timing the complete timing drive.
Once the timing drive is rotated blue link-to-dot
alignment is no longer valid.
Engine base timing can be verified by the following
procedure:
(1) Remove the cylinder head covers. Refer to the
procedure in this section.
Fig. 95 Measuring Secondary Timing Chains For
Wear
1 - SECONDARY TENSIONER ARM
2 - SECONDARY CHAIN TENSIONER PISTON
DRENGINE - 3.7L 9 - 77
VALVE TIMING (Continued)

(2) Using a mirror, locate the TDC arrow on the
front cover (Fig. 96). Rotate the crankshaft until the
mark on the crankshaft damper is aligned with the
TDC arrow on the front cover. The engine is now at
TDC.
(3) Note the location of the V6 mark stamped into
the camshaft drive gears. If the V6 mark on each
camshaft drive gear is at the twelve o'clock position,
the engine is at TDC on the exhaust stroke. If the V6
mark on each gear is at the six o'clock position, the
engine is at TDC on the compression stroke. (Fig.
100)
(4) If both of the camshaft drive gears are off in
the same or opposite directions, the primary chain or
both secondary chains are at fault. Refer to Timing
Chain and Sprockets procedure in this section.
(5) If only one of the camshaft drive gears is off
and the other is correct, the problem is confined to
one secondary chain. Refer to Single camshaft tim-
ing, in this procedure.
(6) If both camshaft drive gear V6 marks are at
the twelve o'clock or the six o'clock position the
engine base timing is correct. Reinstall the cylinder
head covers.
COUNTER BALANCE SHAFT TIMING
(1) Ensure that the engine is at TDC with both
camshaft sprocket V6 marks in the 12 o'clock posi-
tion. (Fig. 100)(2) Look down the left cylinder head chain cavity.
The timing dot on the counter balance shaft drive
gear should be in the 6 o'clock position (Fig. 97).
TIMING - SINGLE CAMSHAFT
NOTE: to adjust the timing on one camshaft, pre-
form the following procedure.
(1) Using Chain Tensioner Wedge (Fig. 99), Special
Tool 8379, stabilize the secondary chain drive. For
reference purposes, mark the chain-to-sprocket posi-
tion. (Fig. 98)
(2) Remove the camshaft drive gear retaining bolt.
(3) Carefully remove the camshaft drive gear from
the camshaft.
(4) Re-index the camshaft drive gear in the chain
until the V6 mark is at the same position as the V6
mark on the opposite camshaft drive gear.
(5) Using Special Tool 8428 Camshaft Wrench,
rotate the camshaft until the alignment dowel on the
camshaft is aligned with the slot in the camshaft
drive gear.
CAUTION: Remove excess oil from camshaft
sprocket retaining bolt before reinstalling bolt. Fail-
ure to do so may cause over-torqueing of bolt
resulting in bolt failure.
Fig. 96 Engine Top Dead Center (TDC) Indicator
Mark
1 - TIMING CHAIN COVER
2 - CRANKSHAFT TIMING MARKS
Fig. 97 COUNTERBALANCE SHAFT ALIGNMENT
MARKS
1 - COUNTERBALANCE SHAFT GEAR
2 - TIMING MARK
3 - IDLER SPROCKET GEAR
9 - 78 ENGINE - 3.7LDR
VALVE TIMING (Continued)

(8) Rotate the crankshaft two full revolutions, then
verify that the camshaft drive gear V6 marks are in
fact aligned.
(9) Install the cylinder head covers. Refer to Cylin-
der Head Cover in this section.
BALANCE SHAFT
REMOVAL
(1) Remove the primary and secondary timing
chains. Refer to TIMING CHAIN and SPROCKET.
NOTE: The balance shaft and gear are serviced as
an assembly. Do not attempt to remove the gear
from the balance shaft.Remove the retaining bolt
from the counterbalance shaft thrust plate (Fig.
101).
(2) Using Special Tool 8641 Counterbalance shaft
remover/installer tool, remove the counterbalance
shaft from the engine (Fig. 102).
INSTALLATION
NOTE: The balance shaft and gear are serviced as
an assembly. Do not attempt to remove the gear
from the balance shaft.
(1) Coat counterbalance shaft bearing journals
with clean engine oil.
NOTE: The balance shaft is heavy, and care should
be used when installing shaft, so bearings are not
damaged.
(2) Using Special Tool 8641 Counterbalance shaft
remover/installer tool, carefully install counterbal-
ance shaft into engine.
(3) Install Counterbalance shaft thrust plate
retaining bolt finger tight.Do not tighten bolt at this
time.
(4) Position the right side of the thrust plate with
the right chain guide bolt, install bolt finger tight.
(5) Torque the thrust plate retaining bolt to 28
N´m (250 in. lbs.).
(6) Remove the chain guide bolt so that guide can
be installed.
Fig. 101 Counterbalance Shaft Retaining Plate
1 - IDLER SHAFT
2 - COUNTERBALANCE SHAFT THRUST PLATE
3 - COUNTERBALANCE SHAFT DRIVE GEAR
4 - RETAINING BOLT
Fig. 102 Counterbalance Shaft Removal/Installation
Tool
1 - COUNTERBALANCE SHAFT REMOVAL AND INSTALLATION
TOOL
2 - COUNTERBALANCE SHAFT THRUST PLATE
9 - 80 ENGINE - 3.7LDR
VALVE TIMING (Continued)