app DODGE RAM 2003 Service Repair Manual
[x] Cancel search | Manufacturer: DODGE, Model Year: 2003, Model line: RAM, Model: DODGE RAM 2003Pages: 2895, PDF Size: 83.15 MB
Page 1620 of 2895
²Possible indications of the cylinder head gasket
leaking between a cylinder and an adjacent water
jacket are:
þ Engine overheating
þ Loss of coolant
þ Excessive steam (white smoke) emitting from
exhaust
þ Coolant foaming
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine if an engine cylinder head gasket is
leaking between adjacent cylinders, follow the proce-
dures in Cylinder Compression Pressure Test in this
section. An engine cylinder head gasket leaking
between adjacent cylinders will result in approxi-
mately a 50±70% reduction in compression pressure.
CYLINDER-TO-WATER JACKET LEAKAGE TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING WITH COOLANT PRES-
SURE CAP REMOVED.
VISUAL TEST METHOD
With the engine cool, remove the coolant pressure
cap. Start the engine and allow it to warm up until
thermostat opens.
If a large combustion/compression pressure leak
exists, bubbles will be visible in the coolant.COOLING SYSTEM TESTER METHOD
WARNING: WITH COOLING SYSTEM TESTER IN
PLACE, PRESSURE WILL BUILD UP FAST. EXCES-
SIVE PRESSURE BUILT UP, BY CONTINUOUS
ENGINE OPERATION, MUST BE RELEASED TO A
SAFE PRESSURE POINT. NEVER PERMIT PRES-
SURE TO EXCEED 138 kPa (20 psi).
Install Cooling System Tester 7700 or equivalent to
pressure cap neck. Start the engine and observe the
tester's pressure gauge. If gauge pulsates with every
power stroke of a cylinder a combustion pressure
leak is evident.
CHEMICAL TEST METHOD
Combustion leaks into the cooling system can also
be checked by using Bloc-Chek Kit C-3685-A or
equivalent. Perform test following the procedures
supplied with the tool kit.
REMOVAL
(1) Disconnect the negative cable from the battery.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Remove the heat shields (Fig. 7).
(4) Remove the intake manifold-to-generator
bracket support rod. Remove the generator (Refer to
8 - ELECTRICAL/CHARGING/GENERATOR -
REMOVAL).
(5) Remove closed crankcase ventilation system.
(6) Disconnect the evaporation control system.
(7) Remove the air cleaner.
(8) Perform the Fuel System Pressure release pro-
cedure (Refer to 14 - FUEL SYSTEM/FUEL DELIV-
ERY - STANDARD PROCEDURE). Disconnect the
Fig. 6 Cylinder Head Assembly
1 - SPARK PLUG
2 - INTAKE VALVES
3 - SPARK PLUG
4 - INTAKE VALVES
5 - SPARK PLUG
6 - SPARK PLUG
7 - INTAKE VALVE
8 - SPARK PLUG
9 - EXHAUST VALVE
10 - EXHAUST VALVES
11 - EXHAUST VALVES
Fig. 7 Spark Plug Wire Heat Shields (Left Side
Shown)
1 - EXHAUST MANIFOLD
2 - HEAT SHIELD
DRENGINE 8.0L 9 - 371
CYLINDER HEAD (Continued)
Page 1626 of 2895
REMOVAL
REMOVALÐVALVE STEM SEALS
NOTE: This procedure is done with the cylinder
head installed.
(1) Disconnect the negative cable from the battery.
(2) Set engine basic timing to Top Dead Center
(TDC) and remove air cleaner.
(3) Remove cylinder head covers (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL) and spark plugs (Refer to 8
- ELECTRICAL/IGNITION CONTROL/SPARK
PLUG - REMOVAL).
(4) Using suitable socket and flex handle at crank-
shaft retaining bolt, turn engine so that the piston of
the cylinder to be worked on, is at TDC on the com-
pression stroke.
(5) Remove rocker arms (Refer to 9 - ENGINE/
CYLINDER HEAD/ROCKER ARM / ADJUSTER
ASSY - REMOVAL).
(6) With air hose attached to an adapter installed
in the spark plug hole, apply 620-689 kPa (90-100
psi) air pressure.
(7) Using Valve Spring Compressor Tool
MD-998772A with adapter 6716A (Fig. 19), compress
valve spring and remove retainer valve locks and
valve spring.
(8) Remove the valve stem seal.
REMOVALÐVALVES AND VALVE SPRINGS
(1) Remove the cylinder head (Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
(2) Special studs must be used to adapt the Valve
Spring Compressor Tool to the V-10 cylinder head
(Fig. 20). Install the metric end into the Special Tool
MD998772A and the 5/16 end into the cylinder head.
Fig. 18 Testing Valve Spring for Compressed
1 - TORQUE WRENCH
2 - VALVE SPRING TESTER
Fig. 19 Valve Spring Compressor MD-998772A with
Adaptor 6716-A and Screw 6765
1 - SPECIAL TOOL MD 998772A
2 - SPECIAL TOOL 6765
3 - SPECIAL TOOL 6716A
4 - AIR HOSE
Fig. 20 Special Studs 6715 for V-10 Engine
1 - SPECIAL TOOL 6715
DRENGINE 8.0L 9 - 377
INTAKE/EXHAUST VALVES & SEATS (Continued)
Page 1628 of 2895
(8) The cylinder head cover gasket can be used
again. Install the gasket onto the head rail.For the
left side the number tab is at the front of
engine with the number up. For the right side
the number tab is at the rear of engine with the
number up.
CAUTION: The cylinder head cover fasteners have a
special plating. DO NOT use alternative fasteners.
(9) Install cylinder head cover (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION) (Fig. 24).
(10) Install closed crankcase ventilation system.
(11) Connect the evaporation control system.
(12) Install air cleaner.
(13) Connect the negative cable to the battery.
(14) Road test vehicle and check for leaks.
INSTALLATIONÐVALVES AND VALVE SPRINGS
(1) Clean valves thoroughly. Discard burned,
warped and cracked valves.(2) Remove carbon and varnish deposits from
inside of valve guides with a reliable guide cleaner.
(3) Measure valve stems for wear. If wear exceeds
0.051 mm (0.002 inch), replace the valve.
(4) Make sure there are no burrs on valve stems.
(5) Coat valve stems with lubrication oil. Insert
valves into valve guides in cylinder head.
(6) Install new seals on all valve guides(BLACK
on intake and BROWN on exhaust). Install valve
springs and valve retainers.
(7) Compress valve springs with Valve Spring
Compressor Tool MD-998772A and adapter 6716A,
install locks and release tool. Tap the retainer with a
brass or heavy plastic hammer to ensure locks have
been seated.
(8) If valves and/or seats were ground, measure
the installed height of springs. Make sure the mea-
surement is taken from bottom of spring seat in cyl-
inder head to the bottom surface of spring retainer. If
spacers are installed, measure from the top of spacer.
If height is greater than 42.86 mm (1-11/16 inches),
install a 1.587 mm (1/16 inch) spacer in head coun-
terbore. Ensure this brings spring height back to nor-
mal, 41.27 to 42.86 mm (1-5/8 to 1-11/16 inch).
(9) Install the cylinder head (Refer to 9 - ENGINE/
CYLINDER HEAD - INSTALLATION).
ROCKER ARM / ADJUSTER
ASSY
REMOVAL
(1) Disconnect spark plug wires by pulling the boot
straight out in line with plug.
(2) Remove cylinder head cover and gasket (Refer
to 9 - ENGINE/CYLINDER HEAD/CYLINDER
HEAD COVER(S) - REMOVAL).
(3) Remove the rocker arm bolts and the rocker
arm assembly (Fig. 25). Place rocker arm assemblies
on a bench in the same order as removed.
(4) Remove the push rods and place them on a
bench in the same order as removed.
INSTALLATION
CAUTION: DO NOT rotate or crank the engine dur-
ing or immediately after rocker arm installation.
Allow the hydraulic roller tappets adequate time to
bleed down (about 5 minutes).
Fig. 24 Cylinder Head Covers
1 - CYLINDER HEAD COVER
2 - CYLINDER HEAD COVER GASKET
DRENGINE 8.0L 9 - 379
INTAKE/EXHAUST VALVES & SEATS (Continued)
Page 1629 of 2895
(1) Install the push rods in the same order as
removed.
(2) Install rocker arm assemblies in the same
order as removed. Tighten the rocker arm bolts to 53
N´m (40 ft. lbs.) torque.
(3) Install cylinder head cover and gasket (Refer to
9 - ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
(4) Connect spark plug wires.
ENGINE BLOCK
CLEANING
Clean cylinder block thoroughly and check all core
hole plugs for evidence of leaking.
INSPECTION
Examine block for cracks or fractures.
The cylinder walls should be checked for out-of-
round and taper with Cylinder Bore Indicator Tool,
Special tool 6879 or equivalent. The cylinder block
should be bored and honed with new pistons and
rings fitted if:
²The cylinder bores show more than 0.127 mm
(0.005 inch) out-of-round.
²The cylinder bores show a taper of more than
0.254 mm (0.010 inch).
²The cylinder walls are badly scuffed or scored.
Boring and honing operation should be closely coor-
dinated with the fitting of pistons and rings so spec-
ified clearances may be maintained.
CAMSHAFT & BEARINGS (IN
BLOCK)
REMOVAL
REMOVALÐCAMSHAFT BEARINGS
This procedure requires that the engine is removed
from the vehicle.
(1) With engine completely disassembled, drive out
rear cam bearing core hole plug.
NOTE: It is not advisable to attempt to replace cam-
shaft bearings unless special removal and installa-
tion tools are available, such as recommended tool
8544 Camshaft Bushing Remover Installer.
(2) Using recommended tool 8544 Camshaft Bush-
ing Remover Installer, Drive out bearing shells.
REMOVALÐCAMSHAFT
(1) Remove rocker arms and push rods (Refer to 9
- ENGINE/CYLINDER HEAD/ROCKER ARM /
ADJUSTER ASSY - REMOVAL). Identify each part
so it can be installed in its original location.
NOTE: The 4 corner tappets can not be removed
without removing the cylinder heads and gaskets.
However, they can be lifted and retained for cam-
shaft removal.
(2) Remove the Bolts retaining the yoke retaining
spider. Remove the yoke retaining spider, tappet
aligning yokes and tappets.
(3) Remove upper and lower intake manifolds
(Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANI-
FOLD - REMOVAL).
(4) Remove timing chain cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL) and timing chain and
sprockets (Refer to 9 - ENGINE/VALVE TIMING/
TIMING BELT/CHAIN AND SPROCKETS -
REMOVAL).
Fig. 25 Rocker Arm - Typical
1 - ROCKER ARMS
2 - ROCKER ARM PEDESTALS
3 - RETAINER
9 - 380 ENGINE 8.0LDR
ROCKER ARM / ADJUSTER ASSY (Continued)
Page 1630 of 2895
(5) Remove camshaft thrust plate (Fig. 26).
(6) Install a long bolt into front of camshaft to aid
in removal of the camshaft. Remove camshaft, being
careful not to damage cam bearings with the cam
lobes.
INSTALLATION
INSTALLATIONÐCAMSHAFT BEARINGS
(1) Install new camshaft bearings using recom-
mended Tool 8544 Camshaft Bushing Remover
Installer, by sliding the new camshaft bearing shell
over proper adapter.
(2) 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.
INSTALLATIONÐCAMSHAFT
(1) Lubricate camshaft lobes and camshaft bearing
journals. Using a long bolt, insert the camshaft into
the cylinder block.
NOTE: Whenever an engine has been rebuilt, a new
camshaft and/or new tappets installed, add 1 pint of
MoparTCrankcase Conditioner, or equivalent. The
oil mixture should be left in engine for a minimum
of 805 km (500 miles). Drain at the next normal oil
change.
(2) Install camshaft thrust plate. Tighten the torx
bolts to 22 N´m (16 ft. lbs.) torque.
(3) Check camshaft end play. The end play should
be 0.051-0.152 mm (0.002-0.006 inch) with a new
thrust plate and up to 0.254 mm (0.010 inch) with a
used thrust plate. If not within these limits install a
new thrust plate.(4) Line up key with keyway in sprocket, then
using Special Tools C-3688, C-3718 and MB990799
install crankshaft timing sprocket. Make sure the
sprocket seats against the crankshaft shoulder (Fig.
27).
(5) Install timing chain and sprocket (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT/CHAIN
AND SPROCKETS - INSTALLATION).
(6) Install the timing chain cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION).
(7) Install the crankshaft pulley/damper (Refer to
9 - ENGINE/ENGINE BLOCK/VIBRATION
DAMPER - INSTALLATION).
(8) Prime oil pump by squirting oil in the oil filter
mounting hole and filling the J-trap of the front tim-
ing cover. When oil is running out, install oil filter
that has been filled with oil.
(9) Each tappet reused must be installed in the
same position from which it was removed.When
camshaft is replaced, all of the tappets must be
replaced.
(10) Install tappets and push rods in their original
location.
(11) Position the tappet aligning yokes and yoke
retaing spider.
(12) Install the retaining spider mounting bolts.
Tighten bolts to 22 N´m (16 ft. lbs.).
Fig. 26 Camshaft
1 - CAMSHAFT
2 - THRUST PLATE
Fig. 27 Crankshaft Sprocket Installation
1 - SPECIAL TOOL C-3688
2 - SPECIAL TOOL C-3718
3 - SPECIAL TOOL MD990799
DRENGINE 8.0L 9 - 381
CAMSHAFT & BEARINGS (IN BLOCK) (Continued)
Page 1632 of 2895
INSTALLATION
When a crankshaft is replaced, all main and con-
necting rod bearings should be replaced with new
bearings. Therefore, selective fitting of the bearings
is not required when a crankshaft and bearings are
replaced.
NOTE: Lubricate crankshaft main bearings with
clean engine oil.
(1) Position upper main bearings into block.
(2) Position the crankshaft into the cylinder block.
(3) Lubricate the main journals with clean engine
oil. Install upper main bearings, caps and bolts. Fol-
low the 2 step tightening sequence, starting with
main bearing cap 1.
(4) Lubricate the connecting rod bearings and jour-
nals with clean engine oil. Carefully install connect-
ing rods to the crankshaft.
(5) Using Special Tool 8359 Seal Installer install
new oil into oil seal retainer.
(6) Using Special Tool 6687 Guide, install the rear
seal retainer with a new gasket.
(7) Install the timing chain cover with a new gas-
ket and oil seal.
(8) Prime oil pump by squirt oil in the oil filter
mounting hole and filling the J-trap of the front tim-
ing cover. When oil is running out, install oil filter
that has been filled with oil.(9) Apply a rearward axial load of 667 N (150
lbs-f) on crankshaft centerline, driving No.3 main cap
and thrust bearing against No.3 bulkhead. Repeat
procedure, driving crankshaft forward to align rear
flange of thrust bearings in a common plane. Front
face of No.1 main cap must not extend forward in
front of face of No.1 bulkhead.
(10) Install the oil pickup tube. Tighten the bolts
to 16 N´m (144 in. lbs.) torque.
(11) Install the oil pan.
CRANKSHAFT MAIN
BEARINGS
STANDARD PROCEDUREÐFITTING
CRANKSHAFT MAIN BEARINGS
Bearing caps are not interchangeable and should
be marked at removal to ensure correct assembly.
Upper and lower bearing halves are NOT inter-
changeable. All lower main bearing halves are inter-
changeable. Upper main bearing halves of No. 2, 4,
and 5 are interchangeable. Upper main bearing
halves of No. 1 and 6 are interchangeable, this also
applies to the lower bearing halves.
The No.3 main bearing is flanged to carry the
crankshaft thrust loads. This bearing is NOT inter-
changeable with any other bearing halves in the
engine. Bearing shells are available in standard and
the following undersizes: 0.25 mm (0.001 inch), 0.051
mm (0.002 inch), 0.076 mm (0.003 inch), 0.254 mm
(0.010 inch) and 0.305 mm (0.012 inch). Never install
an undersize bearing that will reduce clearance
below specifications.
REMOVAL
(1) Remove the oil pan and oil pump pick-up tube
(Refer to 9 - ENGINE/LUBRICATION/OIL PAN -
REMOVAL).
(2) Identify bearing caps before removal. Remove
bearing caps one at a time.
(3) Remove upper half of bearing by inserting
Crankshaft Main Bearing Remover/Installer Tool
C-3059 into the oil hole of crankshaft (Fig. 30).
(4) Slowly rotate crankshaft clockwise, forcing out
upper half of bearing shell.
INSTALLATION
Only one main bearing should be selectively fitted
while all other main bearing caps are properly tight-
ened. All bearing capbolts removed during service
procedures are to be cleaned and oiled before instal-
lation.
When installing a new upper bearing shell, slightly
chamfer the sharp edges from the plain side.
Fig. 29 Main Bearing Identification
1 - MAIN BEARING CAP
2 - UPPER MAIN BEARINGS
3 - CRANKSHAFT
4 - LOWER MAIN BEARINGS
DRENGINE 8.0L 9 - 383
CRANKSHAFT (Continued)
Page 1633 of 2895
(1) Start bearing in place, and insert Crankshaft
Main Bearing Remover/Installer Tool C-3059 into oil
hole of crankshaft (Fig. 30).
(2) Slowly rotate crankshaft counterclockwise slid-
ing the bearing into position. Remove Tool C-3059.
(3) Lubricate the main journals with clean engine
oil. Install main bearing caps and bolts. Follow the 2
step tightening sequence, starting with No. 1 main
bearing cap.
(4) Apply a rearward axial load of 667 N (150
lbs-f) on crankshaft centerline, driving No.3 main cap
and thrust bearing against No.3 bulkhead. Repeat
procedure, driving crankshaft forward to align rear
flange of thrust bearings in a common plane. Front
face of No.1 main cap must not extend forward in
front of face of No.1 bulkhead.
(5) Install the oil pump pick-up tube and oil pan
(Refer to 9 - ENGINE/LUBRICATION/OIL PAN -
INSTALLATION).
CRANKSHAFT OIL SEAL -
FRONT
REMOVAL
REMOVALÐFRONT OIL SEAL - FRONT COVER
INSTALLED
(1) Disconnect the negative cable from the battery.
(2) Remove vibration damper from the crankshaft
(Refer to 9 - ENGINE/ENGINE BLOCK/VIBRATION
DAMPER - REMOVAL).(3) Place a suitable tool behind the lips of the oil
seal to pry the oil seal outward. Be careful not to
damage the crankshaft seal surface of the cover (Fig.
31).
REMOVALÐFRONT OIL SEAL - FRONT COVER
REMOVED
(1) Remove engine front cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(2) Place a suitable tool behind the lips of the oil
seal to pry the oil seal outward. Be careful not to
damage the crankshaft seal surface of the cover.
INSTALLATION
INSTALLATIONÐFRONT OIL SEAL ± FRONT
COVER INSTALLED
(1) Position the crankshaft front oil seal onto seal
installer special tool 6806 and C-3688 (Fig. 32).
Install seal.
(2) Install vibration damper (Refer to 9 - ENGINE/
ENGINE BLOCK/VIBRATION DAMPER - INSTAL-
LATION).
(3) Install serpentine belt (Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).
(4) Install cooling fan and shroud (Refer to 7 -
COOLING/ENGINE/RADIATOR FAN - INSTALLA-
TION).
(5) Connect negative cable to the battery.
(6) Start engine and check for leaks.
INSTALLATIONÐFRONT OIL SEAL - FRONT
COVER REMOVED
(1) Position the crankshaft front oil seal onto seal
installer special tool 6806.
Fig. 30 Upper Main Bearing Removal and
Installation with Tool C-3059
1 - SPECIAL TOOL C-3059
2 - BEARING
3 - SPECIAL TOOL C-3059
4 - BEARINGFig. 31 Timing Chain Cover and Oil Seal
1 - TIMING CHAIN COVER
2 - OIL SEAL
9 - 384 ENGINE 8.0LDR
CRANKSHAFT MAIN BEARINGS (Continued)
Page 1635 of 2895
CRANKSHAFT REAR OIL SEAL
RETAINER
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove the transmission.
(3) Remove the drive plate / flywheel.
(4) Remove the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - REMOVAL).
(5) Remove the rear oil seal retainer mounting
bolts.
(6) Carefully remove the retainer from the engine
block.
INSTALLATION
(1) Throughly clean all gasket resdue from the
engine block.
(2) Use extream care and clean all gasket resdue
from the retainer.
(3) Apply a small amount of MopartSilicone Rub-
ber Adhesive Sealant to the retainer gasket. Position
the gasket onto the retainer.
(4) Position Special Tool 6687 Seal Guide onto the
crankshaft.
(5) Position the retainer and seal over the guide
and onto the engine block.
(6) Install the retainer mounting bolts. Tighten the
bolts to 22 N´m (16 ft. lbs.).
(7) Install the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - INSTALLATION).
(8) Install the drive plate / flywheel.
(9) Install the transmission.
(10) Check and verify engine oil level.
(11) Start engine and check for leaks.
HYDRAULIC LIFTERS
DIAGNOSIS AND TESTINGÐHYDRAULIC
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 207-552 kPa (30-80 psi) at 3,000 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 two con-
ditions 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.
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 create 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 one
tappet will be noisy. When oil level and leaks have
been corrected, operate the engine at fast idle. Run
engine for a sufficient 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 is
caused by a tappet check valve not seating, or by for-
eign particles wedged between the plunger and the
tappet body. This will cause the plunger to stick in
the down position. This heavy click will be accompa-
nied by excessive clearance between the valve stem
and rocker arm as valve closes. In either case, tappet
assembly should be removed for inspection and clean-
ing.
9 - 386 ENGINE 8.0LDR
Page 1636 of 2895
(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. If more than one tappet seems to be
noisy, it's probably not the tappets.
LEAK-DOWN TEST
After cleaning and inspection, test each tappet for
specified leak-down rate tolerance to ensure zero-lash
operation (Fig. 35).
Swing the weighted arm of the hydraulic valve tap-
pet tester away from the ram of the Universal Leak-
Down Tester.
(1) Place a 7.925-7.950 mm (0.312-0.313 inch)
diameter ball bearing on the plunger cap of the tap-
pet.
(2) Lift the ram and position the tappet (with the
ball bearing) inside the tester cup.
(3) Lower the ram, then adjust the nose of the ram
until it contacts the ball bearing. DO NOT tighten
the hex nut on the ram.
(4) Fill the tester cup with hydraulic valve tappet
test oil until the tappet is completely submerged.
(5) Swing the weighted arm onto the push rod and
pump the tappet plunger up and down to remove air.
When the air bubbles cease, swing the weighted arm
away and allow the plunger to rise to the normal
position.
(6) Adjust the nose of the ram to align the pointer
with the SET mark on the scale of the tester and
tighten the hex nut.
(7) Slowly swing the weighted arm onto the push
rod.
(8) Rotate the cup by turning the handle at the
base of the tester clockwise one revolution every 2
seconds.
(9) Observe the leak-down time interval from the
instant the pointer aligns with the START mark on
the scale until the pointer aligns with the 0.125
mark. A normally functioning tappet will require
20-110 seconds to leak-down. Discard tappets with
leak-down time interval not within this specification.
REMOVAL
(1) Disconnect the negative cable from the battery.
(2) Remove the air cleaner.
(3) Remove cylinder head cover (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL).
(4) Remove rocker arm assembly and push rods
(Refer to 9 - ENGINE/CYLINDER HEAD/ROCKER
ARM / ADJUSTER ASSY - REMOVAL). Identify
push rods to ensure installation in original location.
(5) Remove upper and lower intake manifold
(Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANI-
FOLD - REMOVAL).(6) Cut the cylinder head gasket for accessibility if
the end tappets are to be removed.
(7) Remove yoke retainer spider and tappet align-
ing yokes (Fig. 36).
Fig. 35 Leak-Down Tester
1 - POINTER
2 - WEIGHTED ARM
3 - RAM
4 - CUP
5 - HANDLE
6 - PUSH ROD
Fig. 36 Tappets, Aligning Yoke and Yoke Retaining
Spider
1 - TAPPET ALIGNING YOLK
2 - YOKE RETAINING SPIDER
3 - TAPPET
DRENGINE 8.0L 9 - 387
HYDRAULIC LIFTERS (Continued)
Page 1637 of 2895
(8) Pull tappet out of bore with a twisting motion.
If all tappets are to be removed, identify tappets to
ensure installation in original location.
(9) If the tappet or bore in cylinder block is scored,
scuffed, or shows signs of sticking, ream the bore to
next oversize. Replace with oversize tappet.
(10) Check camshaft lobes for abnormal wear.
CLEANING
Clean tappet with a suitable solvent. Rinse in hot
water and blow dry with a clean shop rag or com-
pressed air.
INSTALLATION
(1) Lubricate tappets.
(2) Install tappets in their original positions.
Ensure that the oil bleed hole (if so equipped)
faces forward.
(3) Install tappet aligning yokes. Position the yoke
retainer spider over the tappet aligning yokes (Fig.
36)Install the yoke retaining spider bolts and tighten
to 22 N´m (16 ft. lbs.) torque.
(4) Install the push rods in their original location.
(5) Install the rocker arms (Refer to 9 - ENGINE/
CYLINDER HEAD/ROCKER ARM / ADJUSTER
ASSY - INSTALLATION).
(6) Install lower and upper intake manifold (Refer
to 9 - ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION).
(7) The cylinder head cover gasket can be used
again. Install the gasket onto the head rail.For the
left side the number tab is at the front of
engine with the number up. For the right side
the number tab is at the rear of engine with the
number up.
(8) Install cylinder head cover (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
(9) Install the air cleaner.
CAUTION: To prevent damage to valve mechanism,
engine must not be run above fast idle until all
hydraulic tappets have filled with oil and have
become quiet.
(10) Connect the negative cable to the battery.
(11) Road test vehicle and check for leaks.
PISTON & CONNECTING ROD
DESCRIPTION
The pistons (Fig. 37) are elliptically turned so that
the diameter at the pin boss is less than its diameter
across the thrust face. This allows for expansion
under normal operating conditions. Under operating
temperatures, expansion forces the pin bosses away
from each other, causing the piston to assume a more
nearly round shape.
All pistons are machined to the same weight,
regardless of size, to maintain piston balance.
The piston pin rotates in the piston only and is
retained by the press interference fit of the piston
pin in the connecting rod.
The pistons have a unique dry-film lubricant coat-
ing baked onto the skirts to reduce friction. The
lubricant is particularly effective during engine
break-in, but with time, the material becomes embed-
ded into cylinder bore walls and continues to reduce
friction.
The pistons are LH and RH bank specific.
Fig. 37 Piston and Connecting RodÐ8.0L Engine
1 - FRONT I.D. TOWARDS THIS SIDE
2 - ORIENTATION BUTTON TOWARDS REAR (R.H. ONLY)
2, 4, 6, 8, 10
3 - ORIENTATION BUTTON TOWARDS FRONT (L.H. ONLY)
1, 3, 5, 7, 9
9 - 388 ENGINE 8.0LDR
HYDRAULIC LIFTERS (Continued)