
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)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - CHECKING
ENGINE OIL PRESSURE
(1) Remove oil pressure sending unit (Fig. 93)and
install gauge assembly C-3292.
(2) Run engine until thermostat opens.
(3) Oil Pressure:
²Curb Idle - 25 kPa (4 psi) minimum
²3000 rpm - 170 - 758 kPa (25 - 110 psi)
(4) If oil pressure is 0 at idle, shut off engine.
Check for a clogged oil pick-up screen or a pressure
relief valve stuck open.
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,
Fig. 93 OIL PRESSURE SENDING UNIT -TYPICAL
1 - BELT
2 - OIL PRESSURE SENSOR
3 - OIL FILTER
4 - ELEC. CONNECTOR
9 - 152 ENGINE - 4.7LDR
LUBRICATION (Continued)

REMOVAL
CAUTION: Cleanliness cannot be overemphasized
when handling or replacing diesel fuel system com-
ponents. This especially includes the fuel injectors,
high-pressure fuel lines and fuel injection pump.
Very tight tolerances are used with these parts. Dirt
contamination could cause rapid part wear and pos-
sible plugging of fuel injector nozzle tip holes. This
in turn could lead to possible engine misfire.
Always wash/clean any fuel system component
thoroughly before disassembly and then air dry.
Cap or cover any open part after disassembly.
Before assembly, examine each part for dirt, grease
or other contaminants and clean if necessary. When
installing new parts, lubricate them with clean
engine oil or clean diesel fuel only.
(1) Disconnect both negative battery cables at both
batteries. Cover and isolate ends of both cables.
(2) Remove intake manifold air intake tube (above
injection pump) and its rubber connector hose (Fig.
7).
(3) Remove accessory drive belt.
(4) Thoroughly clean the rear of injection pump,
and attachment points for its 3 fuel lines (Fig. 8).
Also clean the opposite ends of these same 3 lines at
their attachment points.
(5) Disconnect Fuel Control Actuator (FCA) electri-
cal connector at rear of injection pump (Fig. 9).
CAUTION: Whenever a fuel line fitting is connected
to a secondary fitting, always use a back-up wrench
on the secondary fitting. Do not allow the second-
ary fitting to rotate.
(6) Remove fuel line (injection pump-to-fuel pres-
sure limiting valve).
(7) Remove fuel line (injection pump-to-fuel rail).
Use back-up wrench on fitting at fuel pump.
(8) Remove fuel line (injection pump-to-fuel filter
housing).
(9) Remove fuel pump drive gear access cover
(plate) with a 3/8º drive ratchet. Plate is threaded to
timing gear cover (Fig. 10).
(10) Remove fuel pump drive gear mounting nut
and washer.
(11) Attach C3428B, or L4407A (or equivalent)
gear puller (Fig. 11) to pump drive gear with 2 bolts,
and separate gear from pump (a keyway is not used
on this particular injection pump). Leave drive gear
hanging loose within timing gear cover.
(12) Remove 3 injection pump mounting nuts (Fig.
12), and remove pump from engine.
Fig. 7 INTAKE TUBE AND CONNECTING HOSE
1 - MANIFOLD ABOVE HEATERS
2 - RUBBER CONNECTING HOSE
3 - METAL INTAKE TUBE
4 - CLAMPS (2)
Fig. 8 OVERFLOW VALVE
1 - BANJO BOLTS
2 - PUMP MOUNTING NUTS (3)
3 - FUEL INJECTION PUMP
4 - CASCADE OVERFLOW VALVE
14 - 54 FUEL DELIVERY - DIESELDR
FUEL INJECTION PUMP (Continued)

INSTALLATION
NOTE: If a new transmission is being installed, use
all components supplied with the new transmission.
For example, if a new shift tower is supplied, do not
re-use the original shift tower.
(1) Clean transmission front housing mounting
surface.
(2) Apply light coat of Mopar high temperature
bearing grease or equivalent to contact surfaces (Fig.
126) of following components:
²release fork ball stud.
²release bearing slide surface.
²input shaft splines.
²release bearing bore.
²propeller shaft slip yoke.
(3) Support and secure transmission to jack.
(4) Raise and align transmission input shaft with
clutch disc, then slide transmission into place.
(5) Verify front housing is fully seated. Install
transmission bolts without washers and tighten bolts
into the engine to 41 N´m (30 ft. lbs.). Tighten the
bolts with washers into the transmission to 68 N´m
(50 ft. lbs.) (Fig. 127).(6) Install rear crossmember and tighten nuts to
102 N´m (75 ft. lbs.).
(7) Install transmission rear mounting bolts and
tighten to 68 N´m (50 ft. lbs.).
(8) Install front dust shield tighten bolt to 4.5 N´m
(40 in. lbs.). If cover was removed, install onto the
transmission and engine(Refer to 9 - ENGINE/EN-
GINE BLOCK/STRUCTURAL COVER - INSTALLA-
TION).
(9) Install structural dust cover and tighten the
bolts to 54 N´m (40 ft. lbs.).
(10) Install starter motor.
(11) Install suspension crossmember and tighten
nuts to 102 N´m (75 ft. lbs.).
(12) Connect transmission harnesses to clips on
case and connect switches.
(13) Install slave cylinder and tighten cylinder
nuts to 23 N´m (200 in. lbs.).
(14) Install transfer case and transfer case linkage
if equipped.
(15) Remove transmission jack.
(16) Install propeller shaft/shafts with reference
marks aligned.
(17) Install exhaust on the exhaust manifolds.
(18) Fill transmission with lubricant. Correct fill
level is to bottom edge of fill plug hole.
Fig. 126 LUBRICATION POINTS
1 - RELEASE FORK
2 - FORK BALL STUD
3 - BEARING SLIDE SURFACE
4 - SPLINE
5 - RELEASE BEAING
Fig. 127 TRANSMISSION
1 - BOLT WITHOUT WASHER
2 - BOLT WITH WASHER
DRMANUAL TRANSMISSION - NV3500 21 - 39
MANUAL TRANSMISSION - NV3500 (Continued)