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)
VALVE STAND DOWN
Valve stand down is to maintain the adequate com-
pression ratio.
(1) Invert cylinder head.
(2) Fit each valve to its respective valve guide.
(3) Using a straight edge and feeler gauge (Fig. 9),
check valve head stand down: Inlet valve head stand
down .80 to 1.2 mm (.031 to .047 in.) and exhaust
valve stand down .79 to 1.19 mm (.031 to .047 in).
(4) If valve head stand down is not in accordance
with above, discard original valves, check stand down
with new valves and recut valve seat inserts to
obtain correct stand down.
VALVE GUIDE HEIGHT
(1) Valve Guides height requirement.
(2) Measurement A (Fig. 10): 13.50 - 14.00 mm.
VALVE STEM-TO-GUIDE CLEARANCE
MEASUREMENT
(1) Measure and record internal diameter of valve
guides. Valve guide internal diameter is 8.0 to 8.015
mm (.3149 to .3155 in.).
(2) Measure valve stems and record diameters.
Intake valve stem diameter 7.94 to 7.96 mm (.3125 to
.3133 in). Exhaust valve stem diameter 7.92 to 7.94
mm (.3118 to .31215 in).(3) Subtract diameter of valve stem from internal
diameter of its respective valve guide to obtain valve
stem clearance in valve guide. Clearance of inlet
valve stem in valve guide is .040 to .075 mm (.0015
to .0029 in). Clearance of exhaust valve stem in valve
guide is .060 to .095 mm (.0023 to .0037 in).
(4) If valve stem clearance in valve guide exceeds
tolerances, new valve guides must be installed.
FITTING PISTON RING
(1) Wipe cylinder bore clean. Insert ring and push
down with piston to ensure it is square in bore. The
ring gap measurement must be made with the ring
positioning at least 12 mm (0.50 in.) from bottom of
cylinder bore (Fig. 11). Check gap with feeler gauge.
Top compression ring gap .25 to .50mm (.0098 to
.0196 in.). Second compression ring gap .25 to .35mm
(.0098 to .0137 in.). Oil control ring gap .25 to .58mm
(.0098 to .0228 in.).
(2) If ring gaps exceed dimension given, new rings
or cylinder liners must be fitted. Keep piston rings in
piston sets.
(3) Check piston ring to groove clearance (Fig. 12).
Top compression ring gap .08 to .130mm (.0031 to
.0051 in.). Second compression ring gap .070 to
.102mm (.0027 to .0040 in.). Oil control ring gap .040
to .072mm (.0015 to .0028 in.).
CRANKSHAFT END PLAY
(1) Attach dial indicator to engine block (Fig. 13).
(2) Move crankshaft toward front of engine and
zero indicator.
(3) Move crankshaft toward the rear of engine and
record measurement.
(4) Subtract specified crankshaft end float from
figure obtained. Crankshaft end float 0.08 to
0.21mm.
(5) Select thrust washer which will give correct
end float.
Fig. 9 Checking Valve Stand Down
Fig. 10 Valve Guide Height
Fig. 11 Ring Gap Measurement
9 - 50 ENGINENS/GS
SERVICE PROCEDURES (Continued)
70É using angle torque tool. Then rotate the bolts an
additional 70É following tightening sequence.
(10) Then, tighten the 14mm bolts with special
tool VM-1018 in the following manner:
(11) Side bolts (M1-M2): Tighten M1 bolts to 30
N´m, then rotate them 85É (65). Tighten M2 bolts to
30 N´m, then rotate them 85É (65).
(12)2nd Phase:After 20 minutes of engine oper-
ation at operating temperature, allow engine to cool
down completely. Then retorque the head bolts as fol-
lows:
(13) Central bolts A-L: Starting from bolt A,
slacken and retorque it immediately to 30 N´m + 65É.
Rotate the bolt an additional 65É. Then proceed in
the same way, bolt by bolt, following alphabetical
order, as indicated.
(14) Side bolts M1-M2:Without slackening,
torque bolts M1 then bolts M2 to 90 N´m (66 ft. lbs.).
(15) Tighten intake nuts to 30 N´m (22 ft. lbs.) and
exhaust manifolds nuts to 30 N´m (22 ft. lbs.) speci-
fied torque after completing Phase 2.
(16) If the engine cylinder head is to be replaced
and the original valves used, measure the valve stem
diameter. Only standard size valves can be used with
a service replacement engine cylinder head unless
the replacement head valve stem guide bores are
reamed to accommodate oversize valve stems.
Remove all carbon buildup and reface the valves.
(17) Tighten oil feed lines for rocker arm assem-
blies and oil pressure switch to 13 N´m (112 in. lbs.).
(18) Install push rods and rocker arm assemblies,
tighten nut to 29.4 N´m (264 in. lbs.).(19) Install fuel injectors use tool VM-1012 (refer
to Group 14, Fuel System).
(20) Install valve cover, tighten nuts to 14.7 N´m
(132 in. lbs.).
(21) Connect crankcase breather hose.
(22) Connect the injector sensor wire connector,
and the glow plug connectors.
(23) Install oil feed line, tighten banjo bolts to 12.7
N´m (108 in. lbs), and oil drain line to turbo.
(24) Install water manifold tighten bolts to 12 N´m
(106 in. lbs.).
(25) Install exhaust pipe to turbo elbow, tighten
bolts to 28 N´m (250 in. lbs.).
(26) Install the support strut from block to turbo-
charger exhaust elbow.
(27) Install EGR tube to EGR valve, tighten bolts
to 26 N´m (19 ft. lbs.).
(28) Install intercooler hoses at intake manifold.
(29) Install coolant pressure bottle and hoses.
(30) Install wiper module. Refer to Group 8K,
Windshield Wiper Unit Installation for procedure.
(31) Install intercooler hose at turbocharger tube.
(32) Install fuel injector lines from the pump to
injectors, tighten nuts to 17.6 N´m (156. lbs.).
(33) Connect the upper radiator hose.
(34) Connect negative cable to battery.
(35) Fill the cooling system. Check for leaks.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN DIRECT
LINE WITH THE FAN. DO NOT PUT HANDS NEAR
THE PULLEYS, BELTS OR FAN. DO NOT WEAR
LOOSE CLOTHING.
Fig. 33 Engine Cylinder Head Bolt Tightening Sequence
NS/GSENGINE 9 - 59
REMOVAL AND INSTALLATION (Continued)
THRUST PLATE INSPECTION
Check the thickness (Fig. 40) of the plate at points
a-b-c-d. If the measurement is not between 3.950 -
4.050 it must be changed.
INSTALLATION
(1) Coat the camshaft journals with clean engine
oil and carefully install the camshaft complete with
thrust plate and gear. Tighten the retaining bolts to
24 N´m. Be sure to align the timing marks as shown.(2) Install hydraulic tappets and retaining yokes.
(3) Install cylinder heads.
(4) Push rods, and rocker arm assemblies. In there
original location.
(5) Install valve cover.
(6) Install Timing case cover.
(7) Install Vibration damper.
(8) Reinstall Engine.
CAMSHAFT BEARINGS
This procedure requires that the engine is removed
from the vehicle.
REMOVAL
(1) With engine completely disassembled, drive out
rear cam bearing core hole plug.
(2) Install proper size adapters and horseshoe
washers (part of Camshaft Bearing Remover/Installer
Tool) at back of each bearing shell. Drive out bearing
shells.
INSTALLATION
(1) Install new camshaft bearings with Camshaft
Bearing Remover/Installer Tool by sliding the new
camshaft bearing shell over proper adapter.
(2) Position rear bearing in the tool. Install horse-
shoe lock and by reversing removal procedure, care-
fully drive bearing shell into place.
(3) Install remaining bearings in the same man-
ner. Bearings must be carefully aligned to bring oil
holes into full register with oil passages from the
main bearing. If the camshaft bearing shell oil holes
are not in exact alignment, remove and install them
correctly. Install a new core hole plug at the rear of
camshaft.Be sure this plug does not leak.
CRANKSHAFT MAIN BEARINGS
REMOVAL
(1) Disconnect battery cable.
(2) Remove engine from vehicle, refer to engine
removal in this section.
(3) Install engine to engine stand.
(4) Remove accessary drive system.
(5) Remove cylinder head cover, refer to cylinder
head cover removal in this section.
(6) Remove rocker arm and push rods, refer to
rocker arm and push rod section in this section.
(7) Remove intake, exhaust manifold and turbo-
charger, refer to Group 11, Exhaust System and
Intake Manifold.
(8) Remove water manifold.
(9) Remove oil feed lines to rocker arms.
(10) Remove cylinder heads.
(11) Remove oil pan and oil pick-up.
(12) Remove piston and connecting rods from
crankshaft journals.
Fig. 39 Camshaft Removal
Fig. 40 Camshaft Thrust Plate
NS/GSENGINE 9 - 63
REMOVAL AND INSTALLATION (Continued)
(13) Remove pistons and connecting rods from
block.
(14) Remove vibration damper. Refer to procedure
in this section.
(15) Remove front cover. Refer to procedure in this
section.
(16) Remove oil pump drive gear.
(17) Install special tool VM-1004 onto crankshaft
over gear (Fig. 41).
(18) Remove main bearing oil feed and carrier
locators from block.
(19) Remove flywheel and adaptor plate from
engine block.
(20) Remove thrust bearings from rear main bear-
ing carrier (Fig. 42).
(21) Slide crankshaft and bearing carriers rear-
ward to rear of block. If you encounter difficulty in
removing the complete assembly as previously
described, slide the assembly rearward sufficiently to
gain access to the main bearing carrier bolts. Mark
the carriers for assembly and remove the bolts, two
for each carrier (Fig. 43).
(22) Separate the two halves of each carrier,
remove from the crankshaft and temporarily re-as-
semble the carriers (Fig. 44). Withdraw the crank-
shaft through the rear of the crankcase.
INSTALLATION
NOTE: Assemble engine according to sequence
described, thus saving time and preventing dam-
ages to engine components. Clean parts with a suit-
able solvent and dry them with compressed airbefore assembly. Use new gaskets where applicable
and torque wrenches for correct tightening of com-
ponents.
(1) Thoroughly clean crankcase and oil passages,
and blow dry with compressed air.
(2) Install new main bearing shells in each of the
carrier halves. Assemble the carriers to the crank-
shaft journals, ensuring that the carriers are
installed in their original locations. Secure each car-
rier with the two bolts tightening evenly to 42 N´m
(31 ft. lbs.) (Fig. 44).
(3) Slide special tool (VM-1002) over the crank-
shaft gear and, insert the crankshaft and carrier
assembly into the crankcase in the same manner
used for removal.
(4) Align the holes in the lower carriers, with the
center of the crankcase webs (Fig. 45).
(5) Secure each carrier assembly to the crankcase
with the main bearing oil feed and carrier locators
and tighten them to 54 N´m (40 ft. lbs).
(6) Install rear main bearing carrier onto crank-
shaft ensuring arrow on bearing carrier aligns with
vertical web in center of crankcase.
(7) Install rear oil seal.
(8) Install new O-rings in adaptor plate.
(9) Install adaptor plate and tighten bolts to 47
N´m (35 ft. lbs.).
(10) Install bolts to main bearing carrier and
tighten to 26.5 N´m (20 ft. lbs.).
(11) Position flywheel and O-ring on crankshaft
and align bolt holes.
NOTE: For purposes of checking crankshaft end
play used flywheel bolts may be used. Final assem-
bly requires new flywheel bolts.
(12) Install 2 flywheel bolts, 180É apart, and
tighten bolts to 20 N´m plus 60É (15 ft. lbs.) plus 60É.
(13) Attach dial indicator to engine block.
(14) Move crankshaft toward front of engine and
zero indicator.
(15) Move crankshaft toward the rear of engine
and record measurement.
(16) Subtract specified crankshaft end play from
figure obtained. Crankshaft end play 0.08 to 0.21 mm
(0.0032 to 0.0083 in.).
(17) Select thrust washers which will give correct
end play.
(18) Remove tools and flywheel.
(19) Lubricate thrust washer halves and fit them
into the rear main bearing carrier.
(20) To verify correct end play, install 2 flywheel
bolts 180É apart, and tighten bolts to 20 N´m plus 60É
(15 ft. lbs. plus 60É).
(21) Measure crankshaft end play with a dial
gauge. Crankshaft end play should not exceed 0.08-
Fig. 41 Crankshaft Special Tool VM.1004
9 - 64 ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)
CAUTION: The vacuum pump must be centered in
the block and tighten with two bolts. Ensure that
the pump spins freely. If vacuum pump drags ordoes not spin freely loosen bolts and perform pro-
cedures again.
(28) Before installing oil pump check pump bore
depth in block (A) and pump body height (B) (Fig.
47). Difference between A and B should be
0.020-0.082 mm (.0007 to 0032 in.).
(29) Install oil pump and tighten retaining screws
to 27 N´m (20 ft. lbs.). Check for normal backlash
between pump and crankshaft gears.
(30) Install oil pump drive Gear.
(31) Install front cover. Refer to procedure in this
section.
(32) Install vibration damper. Refer to procedure
in this section.
(33) Install cylinder heads. Refer to procedure in
this section.
(34) Install rocker arms and push rods. Refer to
procedure in this section.
(35) Install cylinder head cover. Refer to procedure
in this section.
(36) Install accessary drive system.
(37) Install engine in vehicle. Refer to procedure in
this section.
(38) Fill engine with the correct amount of fluids
specified.
(39) Connect battery cable.OIL PAN
REMOVAL
(1) Disconnect battery cable.
(2) Raise vehicle on hoist.
Fig. 45 Main Bearing Carrier Alignment
Fig. 46 Measuring Crankshaft End Play
Fig. 47 Oil Pump Bore Depth
9 - 66 ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)
(3) Drain oil.
(4) Remove oil pan bolts (Fig. 48).
(5) Remove oil pan.
INSTALLATION
(1) Install oil pan. Apply a continuous 3 mm bead
of Silicone Sealer to oil pan, install within 10 min-
utes.
(2) Install oil pan bolts and torque bolts to 11 N´m
(8 ft. lbs.).
(3) Install oil drain plug tighten to 79 N´m (58 ft.
lbs).
(4) Lower vehicle.
(5) Fill engine with proper amount of oil.
(6) Connect battery cable.
OIL PUMP
REMOVAL
(1) Raise vehicle on hoist.
(2) Remove right splash shield.
(3) Remove both accessory drive belts. Refer to
Group 7, Cooling.
(4) Remove pump shaft support bracket assembly.
(5) Remove vibration damper. Refer to Vibration
Damper Removal in this section.
NOTE: Crankshaft damper nut is left handed
thread.
(6) Remove front cover. Refer to Timing Gear
Cover Removal in this section.
(7) Remove oil pump.
INSTALLATION
(1) Install new O-ring and lubricate with clean
engine oil.
(2) Install oil pump and tighten retaining screws
to 27.5 N´m (240 in. lbs.).(3) Install front cover. Refer to Timing Gear Cover
Installation in this section.
(4) Install pump shaft support bracket assembly.
CAUTION: Correct torque on the vibration damper
nut is important or engine damage can occur.
(5) Install vibration damper. Torque nut to 441
N´m (325 ft. lbs.)
(6) Install both accessory drive belts. Refer to
Group 7, Cooling.
(7) Install right splash shield.
OIL PUMP PRESSURE RELIEF VALVE
REMOVAL
(1) Remove oil pan.
(2) Remove clip retaining relief valve.
(3) Remove relief valve cap, spring, and plunger
(Fig. 50).
(4) Check relief valve spring length. Relief valve
spring free length is 57.5mm (2.263 in.). If spring
length is less or spring is distorted it must be
replaced.
(5) Check plunger for scoring, replace if necessary.
INSTALLATION
(1) Thoroughly clean all components and relief
valve pocket in cylinder block.
(2) Fit plunger, spring and cap into block.
(3) Compress spring and install retaining clip.
Ensure clip is completely seated in groove.
Fig. 48 Oil Pan
Fig. 49 Oil Pump Drive Gear
NS/GSENGINE 9 - 67
REMOVAL AND INSTALLATION (Continued)
PISTON RINGÐREMOVAL
(1) Identification (ID) mark on face of upper and
intermediate piston rings must point toward piston
crown.
(2) Using a suitable ring expander, remove upper
and intermediate piston rings (Fig. 58).
(3) Remove the upper oil ring side rail, lower oil
ring side rail and then oil ring expander from piston.
(4) Carefully clean carbon from piston crowns,
skirts and ring grooves ensuring the 4 oil holes in
the oil control ring groove are clear.
FITTING PISTON RINGS
(1) Wipe cylinder bore clean. Insert ring and push
down with piston to ensure it is square in bore. The
ring gap measurement must be made with the ring
positioning at least 12 mm (0.50 in.) from bottom of
cylinder bore. Check gap with feeler gauge (Fig. 59).
Top compression ring gap .25 to .50 mm (.0098 to
.0196 in.). Second compression ring gap .25 to .35
mm (.0098 to .0137 in.). Oil control ring gap .25 to
.58 mm (.0098 to .0228 in.).
(2) If ring gaps exceed dimension given, new rings
or cylinder liners must be fitted. Keep piston rings in
piston sets.
(3) Check piston ring to groove clearance (Fig. 60).
Top compression ring gap .08 to .130 mm (.0031 to.0051 in.). Second compression ring gap .070 to .102
mm (.0027 to .0040 in.). Oil control ring gap .040 to
.072 mm (.0015 to .0028 in.).
PISTON RINGSÐINSTALLATION
(1) Install rings on the pistons using a suitable
ring expander (Fig. 58).
(2) Top compression ring is tapered and chromium
plated. The second ring is of the scraper type and
must be installed with scraping edge facing bottom of
the piston. The third is an oil control ring (Fig. 61).
Ring gaps must be positioned, before inserting piston
into the liners, as follows (Fig. 62).
(3) Top ring gap must be positioned at 30 degrees
to the right of the combustion chamber recess (look-
ing at the piston crown from above).
(4) Second piston ring gap should be positioned on
the opposite side of the combustion chamber recess.
(5) Oil control ring gap to be located 30 degrees to
the left of combustion chamber recess.
(6) When assembling pistons check that compo-
nents are installed in the same position as before dis-
Fig. 57 Piston Assembly
Fig. 58 Piston RingsÐRemoving and Installing
Fig. 59 Ring Gap Measurement
9 - 70 ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)