ENGINE DIAGNOSISÐMECHANICAL
CONDITION POSSIBLE CAUSES CORRECTION
LUBRICATING OIL PRESSURE
LOW1. Low oil level. 1a. Check and fill with clean engine
oil.
1b. Check for severe external oil
leaks that could reduce the
pressure.
2. Oil viscosity thin, diluted, or
wrong specification.2. Verify the correct oil is being
used. Check for oil dilution.
3. Improperly operating pressure
switch/gauge3. Verify the pressure switch is
functioning correctly. If not, replace
switch/gauge.
4. Relief valve stuck open. 4. Check/replace valve.
5. Plugged oil filter. 5. Change oil filter. Oil filter change
interval may need to be revised.
6. Oil cooler was replaced, shipping
plugs left in cooler.6. Check/removed shipping plugs.
7. Worn oil pump. 7. Check/replace oil pump.
8. Suction tube loose or seal
leaking.8. Check and replace seal.
9. Worn bearing or wrong bearing
installed.9. Inspect and replace connecting
rod or main bearings. check and
replace piston cooling oil jet.
10. Oil jets under piston loose or
bad fit.10. Check oil jets position.
LUBRICATING OIL LOSS 1. External oil leaks. 1. Visually inspect for oil leaks.
Repair as required.
2. Crankcase being overfilled. 2. Verify that the correct dipstick is
being used.
3. Incorrect oil specification or
viscosity.3a. Make sure the correct oil is
being used.
3b. Look for reduced viscosity from
dilution with fuel.
3c. Review/reduce the oil change
intervals.
4. Oil cooler leak. 4. Check and replace the oil cooler.
5. High blow-by forcing oil out the
breather.5. Check the breather tube area for
signs of oil loss.
9 - 44 ENGINENS/GS
DIAGNOSIS AND TESTING (Continued)
HYDRAULIC TAPPETS
Before disassembling any part of the engine to cor-
rect tappet noise, check the oil pressure. If vehicle
has no oil pressure gauge, install a reliable gauge at
the pressure sending unit. The pressure should be
between 3.5 bars to 5.0 bars at 4000 RPM.
Check the oil level after the engine reaches normal
operating temperature. Allow 5 minutes to stabilize
oil level, check dipstick. The oil level in the pan
should never be above the FULL mark or below the
ADD OIL mark on dipstick. Either of these 2 condi-
tions could be responsible for noisy tappets.
OIL LEVEL HIGH
If oil level is above the FULL mark, it is possible
for the connecting rods to dip into the oil. With the
engine running, this condition could create foam in
the oil pan. Foam in oil pan would be fed to the
hydraulic tappets by the oil pump causing them to
lose length and allow valves to seat noisily.
OIL LEVEL LOW
Low oil level may allow oil pump to take in air.
When air is fed to the tappets, they lose length which
allows valves to seat noisily. Any leaks on intake side
of oil pump through which air can be drawn will cre-
ate the same tappet action. Check the lubrication
system from the intake strainer to the pump cover,
including the relief valve retainer cap. When tappet
noise is due to aeration, it may be intermittent or
constant, and usually more than 1 tappet will be
noisy. When oil level and leaks have been corrected,
operate the engine at fast idle. Run engine for a suf-
ficient time to allow all of the air inside the tappets
to be bled out.
TAPPET NOISE DIAGNOSIS
(1) To determine source of tappet noise, operate
engine at idle with cylinder head covers removed.
(2) Feel each valve spring or rocker arm to detect
noisy tappet. The noisy tappet will cause the affected
spring and/or rocker arm to vibrate or feel rough in
operation.
NOTE: Worn valve guides or cocked springs are
sometimes mistaken for noisy tappets. If such is
the case, noise may be dampened by applying side
thrust on the valve spring. If noise is not apprecia-
bly reduced, it can be assumed the noise is in the
tappet. Inspect the rocker arm push rod sockets
and push rod ends for wear.
(3) Valve tappet noise ranges from light noise to a
heavy click. A light noise is usually caused by exces-
sive leak down around the unit plunger or by the
plunger partially sticking in the tappet body cylinder.
The tappet should be replaced. A heavy click iscaused by a tappet check valve not seating or by for-
eign particles becoming wedged between the plunger
and the tappet body. This will cause the plunger to
stick in the down position. This heavy click will be
accompanied by excessive clearance between the
valve stem and rocker arm as valve closes. In either
case, tappet assembly should be removed for inspec-
tion and cleaning.
(4) The valve train generates a noise very much
like a light tappet noise during normal operation.
Care must be taken to ensure that tappets are mak-
ing the noise. In general, if more than one tappet
seems to be noisy, its probably not the tappets.
SERVICE PROCEDURES
CHECKING OIL LEVEL
To assure proper engine lubrication, the engine oil
must be maintained at the correct level. Check the
oil level at regular intervals, such as every fuel stop.
The best time to check the oil level is about 5 min-
utes after a fully warmed-up engine is shut off, or
before starting the vehicle after it has sat overnight.
Checking the oil while the vehicle is on level
ground, will improve the accuracy of the oil level
readings (Fig. 4).
CHANGING ENGINE OIL AND FILTER
Change engine oil and filter at mileage and time
intervals described in the Maintenance Schedule.
Fig. 4 Checking Engine Oil
NS/GSENGINE 9 - 47
DIAGNOSIS AND TESTING (Continued)
ENGINE OIL CHANGE
WARNING: NEW OR USED ENGINE OIL CAN BE
IRRITATING TO THE SKIN. AVOID PROLONGED OR
REPEATED SKIN CONTACT WITH ENGINE OIL.
CONTAMINANTS IN USED ENGINE OIL, CAUSED BY
INTERNAL COMBUSTION, CAN BE HAZARDOUS TO
YOUR HEALTH. THOROUGHLY WASH EXPOSED
SKIN WITH SOAP AND WATER. DO NOT WASH
SKIN WITH GASOLINE, DIESEL FUEL, THINNER, OR
SOLVENTS, HEALTH PROBLEMS CAN RESULT. DO
NOT POLLUTE, DISPOSE OF USED ENGINE OIL
PROPERLY. CONTACT YOUR DEALER OR GOVERN-
MENT AGENCY FOR LOCATION OF COLLECTION
CENTER IN YOUR AREA.
Run engine until achieving normal operating tem-
perature.
(1) Position the vehicle on a level surface and turn
engine off.
(2) Remove oil fill cap.
(3) Hoist vehicle. Refer to Hoisting and Jacking
Recommendations.
(4) Place a suitable drain pan under crankcase
drain.
(5) Remove drain plug from crankcase and allow
oil to drain into pan (Fig. 5). Inspect drain plug
threads for stretching or other damage. Replace
drain plug if damaged.
(6) Install drain plug in crankcase.
(7) Lower vehicle and fill crankcase with specified
type and amount of engine oil.
(8) Install oil fill cap.
(9) Start engine and inspect for leaks.
(10) Stop engine and inspect oil level.
ENGINE OIL
ENGINE OIL QUALITY
Use only oils conforming to API (American Petro-
leum Institute) quality SG/CD, or CCMC G4. Use
only Diesel engine oil meeting standardMIL-2104C
or API service classificationSG/CD or CCMM PD1.
OIL VISCOSITY
Grade 15W-40 is recommended for temperatures
between +35ÉC to ±10ÉC (95ÉF to 14ÉF). Low viscosity
oils must have the proper API quality or the CCMC
G5 designation. Low viscosity oils are preferred when
minimum temperatures consistently fall below ±12ÉC
(10ÉF).
ENGINE OIL FILTER CHANGE
(1) Position a drain pan under the oil filter.
(2) Using a suitable oil filter wrench loosen filter.
(3) Rotate the oil filter counterclockwise to remove
it from the oil filter base (Fig. 6).
(4) When filter separates from base, tip gasket end
upward to minimize oil spill. Remove filter from vehi-
cle.
(5) With a cloth, wipe clean the gasket sealing sur-
face of oil and grime.
OIL FILTER INSTALLATION
(1) Lightly lubricate oil filter gasket with engine
oil.
(2) Thread filter onto the base. When gasket
makes contact with sealing surface, hand tighten fil-
ter one full turn, do not over tighten.
Fig. 5 Oil Drain Plug
Fig. 6 Oil Filter
9 - 48 ENGINENS/GS
SERVICE PROCEDURES (Continued)
(3) Add oil, verify crankcase oil level and start
engine. Inspect filter area for oil leaks.
TIMING PROCEDURE
CAUTION: If a timing gear is removed you must
loosen the rocker arm supports before rotating the
crankshaft or camshaft. This will prevent the valves
hitting the pistons.
For the engine components to be in proper timing
order, the timing gear marks (dots) must be aligned
as shown in (Fig. 7). To facilitate reassembly, align
the timing marks as shown in (Fig. 7), or mark the
timing gear positions before removal of any marked
gears or gear driven component(s).
VALVE AND SEAT REFACING
VALVE REFACING
(1) Use a valve refacing machine to reface the
intake and exhaust valves to the specified angle.
(2) After refacing, a margin of at least 4.52-4.49
mm (.178-.177 inch) must remain (Fig. 8). If the mar-
gin is less than 4.49 mm (.177 inch), the valve must
be replaced.
VALVE SEAT REFACING
(1) Install a pilot of the correct size in the valve
guide bore. Reface the valve seat to the specified
angle with a good dressing stone. Remove only
enough metal to provide a smooth finish.
(2) Use tapered stones to obtain the specified seat
width when required.
Fig. 7 Aligning Timing Marks
Fig. 8 Valve Specification
NS/GSENGINE 9 - 49
SERVICE PROCEDURES (Continued)
ENGINE ASSEMBLY
REMOVAL
(1) Disconnect the battery.
(2) Remove the air cleaner assembly and inlet
hose.
(3) Remove both hoses at intercooler and engine.
(4) Disconnect EGR vacuum hose.
(5) Disconnect brake booster vacuum hose.
(6) Disconnect oil pressure switch connector (Fig.
19).
(7) Disconnect Wiring harness bracket at transaxle
shift tower.
(8) Disconnect transaxle wiring at speed sensor,
crank sensor, and backup light switch.
(9) Remove both transmission shift cables at trans-
mission.
(10) Remove negative battery cable at cylinder
block (Fig. 19).
(11) Remove oil separator.
(12) Remove connectors at coolant temperature
sensor and A/C compressor.
(13) Disconnect fuel injection pump wiring connec-
tors (Fig. 19).
(14) Disconnect glow plug connectors.
(15) Disconnect electrical connector at number 1
fuel injector.
(16) Raise vehicle on hoist.
(17) Remove right side splash shield (Fig. 20).
WARNING: THE COOLANT IN A RECENTLY OPER-
ATED ENGINE IS HOT AND PRESSURIZED. USE
CARE TO PREVENT SCALDING BY HOT COOLANT.CAREFULLY RELEASE THE PRESSURE BEFORE
REMOVING THE RADIATOR DRAIN COCK AND CAP.
(18) Drain the cooling system (refer to Group 7,
Cooling).
(19) Lower vehicle.
(20) Remove Coolant pressure bottle and discon-
nect low coolant level sensor.
(21) Disconnect both heater hoses.
(22) Remove the lower radiator hose.
(23) Remove the upper radiator hose.
(24) Remove fuel line at injector pump and cap.
(25) Remove power steering reservoir and reposi-
tion.
(26) Remove upper radiator crossmember.
(27) Disconnect cooling fan module connector.
Fig. 18 Shift Cables at Rear MountFig. 19 Component Locations
Fig. 20 Right Side Splash Shield
NS/GSENGINE 9 - 53
REMOVAL AND INSTALLATION (Continued)
(3) If internal diameter of original bearing is being
checked and figures are not within specifications,
new bearings must be used.
(4) Check crankshaft main bearing journals to
bearing clearances. Clearances of main bearings is
.03 to .088mm (.0011 to .0035 in.).
OIL PAN
Remove all gasket material from cylinder block. Be
careful not gouge pan sealing surface.
CYLINDER LINER
INSPECTION
The cylinder walls should be checked for out-of-
round and taper with dail bore gauge. The cylinder
bore out-of-round is 0.100 mm (.0039 inch) maximum
and cylinder bore taper is 0.100 mm (0.0039 inch)
maximum. If the cylinder walls are badly scuffed or
scored, new liners should be installed and honed, and
new pistons and rings fitted.
Measure the cylinder bore at three levels in direc-
tions A and B (Fig. 79). Top measurement should be
10 mm (3/8 inch) down and bottom measurement
should be 10 mm ( 3/8 inch.) up from bottom of bore.
SPECIFICATIONS
2.5L VM DIESEL
DESCRIPTION...........SPECIFICATIONS
Type ......................425CLIEE (36B)
Number of Cylinder......................4
Bore..............................92mm
Stroke............................94mm
Capacity.......................2499.5 cm3
Injection Order.....................1-3-4-2
Compression Ratio...............21:1 (60.5)
Crankshaft
Front Journal Diameter....................
Nominal.................62.985±63.000 mm
±0.25....................62.735±62.750 mm
±0.125...................62.860±62.875 mm
Front Bearing Diameter....................
Nominal.................63.043±63.088 mm
±0.25....................62.793±62.838 mm
±0.125...................62.918±62.963 mm
Clearance Between Journal and Bearing:
0.043±0.103 mm..........................
Center Journal Diameter...................
Fig. 77 Piston, Connecting Rod and Pin
Fig. 78 Bearing Clearance
Fig. 79 Liner Inspection
9 - 78 ENGINENS/GS
CLEANING AND INSPECTION (Continued)
REMOVAL AND INSTALLATION
EXHAUST PIPES, MUFFLERS AND TAILPIPES
REMOVAL
(1) Raise vehicle on hoist and apply penetrating
oil to clamp bolts and nuts of component being
removed.
(2) Loosen clamps and supports (Fig. 5) and (Fig.
4) from exhaust system to permit alignment of parts
during assembly.
(3) When removing tailpipe, raise rear of vehicle
to relieve body weight from rear springs to provide
clearance between pipe and rear axle parts.
(4) Clean ends of pipes or muffler to assure mat-
ing of all parts. Discard broken or worn insulators,
rusted clamps, supports and attaching parts.When
replacement is required on any component of
the exhaust system. It is important that origi-nal equipment parts (or their equivalent) be
used;
²To insure proper alignment with other parts in
the system.
²Provide acceptable exhaust noise levels and does
not change exhaust system back pressure that could
effect emissions and performance.
INSTALLATION
(1) Assemble pipes, muffler support and clamp
loosely to permit alignment of all parts.
(2) Beginning at front of system, align and clamp
each component to maintain position and proper
clearance with underbody parts.
(3) Tighten the clamp and support to the proper
torques and clearances (Fig. 4).
UPPER INTAKE MANIFOLDÐ2.4L ENGINE
REMOVAL
(1) Disconnect negative cable from battery.
(2) Disconnect air intake tube and resonator box
from throttle body and remove.
(3) Remove connector from throttle position sensor
(Fig. 6).
(4) Remove connector from idle air control motor
(Fig. 6).
(5) Remove connector from MAP sensor (Fig. 11).
Fig. 4 Exhaust System Components
Fig. 5 Band Clamp
11 - 4 EXHAUST SYSTEM AND INTAKE MANIFOLDNS
(3) Fold tangs on regulator retainer over tabs on
housing.
FUEL PUMP INLET STRAINER
REMOVAL
(1) Remove fuel pump module. Refer to Fuel Pump
Module Removal in this section.
(2) Using a thin straight blade screwdriver, pry
back the locking tabs on fuel pump reservoir and
remove the strainer (Fig. 20).
(3) Remove strainer O-ring from the fuel pump
reservoir body.
(4) Remove any contaminants in the fuel tank by
washing the inside of the fuel tank.
INSTALLATION
(1) Lubricate the strainer O-ring with clean engine
oil.
(2) Insert strainer O-ring into outlet of strainer so
that it sits evenly on the step inside the outlet.
(3) Push strainer onto the inlet of the fuel pump
reservoir body. Make sure the locking tabs on thereservoir body lock over the locking tangs on the
strainer.
(4) Install fuel pump module. Refer to Fuel Pump
Module Installation in this section.
FUEL LEVEL SENSOR
REMOVAL
Remove fuel pump module. Refer to Fuel Pump
Module in this section.
(1) Depress retaining tab and remove the fuel
pump/level sensor connector from theBOTTOMof
the fuel pump module electrical connector (Fig. 21).
NOTE: The pump module harness on TOP of flange
is not serviceable or removable.
(2) Pull off blue locking wedge (Fig. 22).
(3) Using a small screwdriver lift locking finger
away from terminal and push terminal out of connec-
tor (Fig. 23).
Fig. 19 Fuel Pressure Regulator O-rings
Fig. 20 Inlet Strainer Removal
Fig. 21 Fuel Pump/Level Sensor Electrical
Connector
Fig. 22 Wire Terminal Locking Wedge
NSFUEL SYSTEM 14 - 15
REMOVAL AND INSTALLATION (Continued)