aligning yokes. The yokes are secured by an align-
ment yoke retainer (Fig. 4).
PRELIMINARY STEP TO CHECKING THE
HYDRAULIC TAPPETS
Before disassembling any part of the engine to cor-
rect tappet noise, read the oil pressure at the gauge.
Install a reliable gauge at pressure sending unit if
vehicle has no oil pressure gauge and check the oil
level in the oil pan. The pressure should be between
30 and 80 psi (206.8 to 551.6 kPa) at 2000 rpm.
The oil level in the pan should never be above the
MAX mark on dipstick, or below the MIN mark.
Either of these two conditions could be responsible
for noisy tappets.Oil Level Check: stop engineafter reaching normal operating temperature.
Allow 5 minutes to stabilize oil level, check dipstick.
OIL LEVEL TOO HIGH
If oil level is above the MAX mark on dip stick, it
is possible for the connecting rods to dip into the oil
while engine is running and create foam. Foam in oil
pan would be fed to the hydraulic tappets by the oil
pump causing them to become soft and allow valves
to seat noisily.
OIL LEVEL TOO LOW
Low oil level may allow pump to take in air which
when fed to the tappets, causes them to become soft
and allows valves to seat noisily. Any leaks on intake
side of 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,
engine should be operated at fast idle to allow all of
the air inside of the tappets to be bled out.
VALVE TRAIN NOISE DIAGNOSIS
To determine source of valve train noise, operate
engine at idle with cylinder head covers removed and
listen for source of the noise.
Fig. 3 3.3/3.8L V-6 Engines
Fig. 4 Roller Tappets Aligning Yoke and Retainer
NS3.3/3.8L ENGINE 9 - 95
DIAGNOSIS AND TESTING (Continued)
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.
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 which will
necessitate replacing the tappet, or by the plunger
partially sticking in the tappet body cylinder. A heavy
click is caused either by a tappet check valve not
seating, or by foreign particles becoming wedged
between the plunger and the tappet body causing 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 inspection and cleaning.
CHECKING ENGINE OIL PRESSURE
Check oil pressure using gauge at oil pressure
switch location. Oil pressure should be 34.47 kPa (5
psi.) at idle or 205 to 551 kPa (30 to 80 psi.) at 3000
RPM.
(1) Remove pressure sending unit and install oil
pressure gauge (Fig. 5).
CAUTION: If oil pressure is 0 at idle, do not run
engine at 3000 RPM.
(2) Warm engine at high idle until thermostat
opens.
SERVICE PROCEDURES
VALVE TIMING
(1) Remove front cylinder head cover and all 6
spark plugs.
(2) Rotate engine until the #2 piston is at TDC of
the compression stroke.
(3) Install a degree wheel on the crankshaft pulley.
(4) With proper adaptor, install a dial indicator
into #2 spark plug hole. Using the indicator find TDC
on the compression stroke.
(5) Position the degree wheel to zero.
(6) Remove dial indicator from spark plug hole.
(7) Place a 5.08 mm (0.200 in.) spacer between the
valve stem tip of #2 intake valve and rocker arm pad.
Allow tappet to bleed down to give a solid tappet
effect.
(8) Install a dial indicator so plunger contacts the
#2 intake valve spring retainer as nearly perpendic-
ular as possible. Zero the indicator.
(9) Rotate the engine clockwise until the intake
valve has lifted .254 mm (0.010 in.).
CAUTION: Do not turn crankshaft any further
clockwise as intake valve might bottom and result
in serious damage.
(10) Degree wheel should read 6 degrees BTDC to
6 degrees ATDC.
MEASURING TIMING CHAIN FOR STRETCH
(1) Place a scale next to timing chain so that any
movement of chain may be measured.
(2) Place a torque wrench and socket on camshaft
sprocket attaching bolt and apply torque in direction
of crankshaft rotation to take up slack; 41 N´m (30 ft.
lb.) with cylinder head installed or 20 N´m (15 ft. lb.)
with cylinder heads removed.With a torque
applied to the camshaft sprocket bolt, crank-
shaft should not be permitted to move. It may
be necessary to block crankshaft to prevent
rotation.
(3) Holding a scale even, with dimension reading
as shown (Fig. 6), along edge of chain links. Apply
torque in the reverse direction to 41 N´m (30 ft. lbs.)
with cylinder heads installed, or 20 N´m (15 ft. lbs.)
with cylinder heads removed. Check amount of chain
movement.
(4) Install a new timing chain, if its movement
exceeds 3.175 mm (1/8 inch).
(5) If chain is not satisfactory, refer to Timing
Chain Removal and Installation in this section.
Fig. 5 Checking Oil Pump Pressure
9 - 96 3.3/3.8L ENGINENS
DIAGNOSIS AND TESTING (Continued)
with an old bearing half. Do not file the rods or
bearing caps.
(1) Follow procedure specified in the Standard Ser-
vice Procedure Section for Measuring Main Bearing
Clearance and Connecting Rod Bearing Clearance
(Fig. 11).
NOTE: The rod bearing bolts should be examined
before reuse. If the threads are necked down the
bolts should be replaced (Fig. 13). Necking can be
checked by holding a scale or straight edge againstthe threads. If all the threads do not contact the
scale the bolt should be replaced.
(2) Before installing the nuts the threads should
be oiled with engine oil.
(3) Install nuts finger tight on each bolt then alter-
nately torque each nut to assemble the cap properly.
(4) Tighten the nuts to 54 N´m PLUS 1/4 turn (40
ft. lbs. PLUS 1/4 turn).
(5) Using a feeler gauge, check connecting rod side
clearance (Fig. 12). Refer to Connecting Rod Specifi-
cation Chart.
FITTING MAIN BEARINGS
CRANKSHAFT OIL CLEARANCE
Measure the journal outside diameter as shown in
(Fig. 14). Refer to Crankshaft Specification Chart.
PISTON RING SPECIFICATION CHART
Ring Position Ring Gap Wear Limit Groove Clearance Maximum Clearance
Upper Ring 0.30 - 0.55 mm
(0.012 - 0.022 in.)1.0 mm (0.039 in.) 0.030 - 0.085 mm
(0.001 - 0.003 in.)0.10 mm (0.004 in.)
Intermediate Ring 0.30 - 0.55 mm
(0.012 - 0.022 in.)1.0 mm (0.039 in.) 0.030 - 0.095 mm
(0.001 - 0.0037 in.)0.10 mm (0.004 in.)
Oil Control Ring 0.25 - 1.00 mm
(0.010 - 0.039 in.)1.88 mm (0.074 in.) 0.014 - 0.266 mm
(0.0005 - 0.009 in.)0.266 mm (0.009 in.)
Fig. 9 Check Gap on Piston Rings
Fig. 10 Measuring Piston Ring Side Clearance
Fig. 11 Checking Connecting Rod Bearing
Clearance
9 - 98 3.3/3.8L ENGINENS
SERVICE PROCEDURES (Continued)
PLASTIGAGE (OIL CLEARANCE)
MEASUREMENT
(1) Remove oil from journal and bearing shell.
(2) Install crankshaft.
(3) Cut plastigage to same length as width of the
bearing and place it in parallel with the journal axis
(Fig. 15).
(4) Install the main bearing cap carefully and
tighten the bolts to specified torque.
CAUTION: Do not rotate crankshaft or the plasti-
gage will be smeared.(5) Carefully remove the bearing cap and measure
the width of the plastigage at the widest part using
the scale on the plastigage package (Fig. 15). Refer to
Crankshaft Specification Chart for proper clearances.
If the clearance exceeds the specified limits, replace
the main bearing(s) and if necessary, have the crank-
shaft machined to next undersize.
CAUTION: Do not rotate crankshaft or the Plasti-
gage may be smeared.
CRANKSHAFT END PLAY
DIAL INDICATOR METHOD
(1) Mount a dial indicator to front of engine, locat-
ing probe on nose of crankshaft (Fig. 16).
Fig. 12 Checking Connecting Rod Side Clearance
CONNECTING ROD SPECIFICATION CHART
Connecting Rod Bearing Clearance
New Part: 0.019 - 0.073 mm
(0.0008 - 0.0029 in.)
Wear Limit: 0.074 mm
(0.003 in.)
Connecting Rod Side Clearance
New Part: 0.13 - 0.32 mm
(0.005 - 0.013 in.)
Wear Limit: 0.38 mm
(0.015 in.)
Fig. 13 Check for Stretched (Necked) Bolts
CRANKSHAFT SPECIFICATION CHART
Crankshaft End-Play
New Part: 0.09 - 0.24 mm
(0.0036 - 0.0095 in.)
Wear Limit: 0.38 mm
(0.015 in.)
Main Bearing Clearance
New Part: 0.011 - 0.059 mm
(0.0005 - 0.0024 in.)
Wear Limit: 0.076 mm
(0.003 in.)
Crankshaft Main Bearing Journal
Standard Size: 63.992 - 64.013 mm
(2.5194 - 2.5202 in.)
Crankshaft Connecting Rod Journal
Standard Size: 57.989 - 58.005 mm
(2.2831 - 2.2837 in.)
Fig. 14 Measure Crankshaft Journal O.D.
NS3.3/3.8L ENGINE 9 - 99
SERVICE PROCEDURES (Continued)
(20) Remove rear transmission mount and bracket.
(21) Remove power steering pump and bracket
assembly.
(22) Remove wiring harness and connectors from
front of engine.
(23) Remove bending braces and install tool num-
ber 6912 on engine.
(24) Remove transmission inspection cover and
mark flexplate to torque converter.
(25) Remove driveplate to torque converter bolts.
(26) Lower the vehicle.
(27) Remove ground straps to body.
(28) Raise vehicle enough to allow engine dolly
Special Tool 6135 and cradle Special Tool 6710 with
post Special Tool 6848 and adaptor Special Tool 6909
to be installed under vehicle (Fig. 28).
(29) Loosen cradle engine mounts to allow move-
ment for positioning onto engine locating holes on the
engine. Lower vehicle and position cradle mounts
until the engine is resting on mounts. Tighten
mounts to cradle frame. This will keep mounts from
moving when removing or installing engine and
transmission.
(30) Lower vehicle so the weight ofONLY THE
ENGINE AND TRANSMISSIONis on the cradle.
(31) Remove right engine mount assembly and left
transmission mount through bolt. Refer to Engine
Mounts Section of this Group.
(32) Raise vehicle slowly. It may be necessary to
move the engine/transmission assembly on the cradle
to allow for removal around body flanges.INSTALLATION
(1) Position engine and transmission assembly
under vehicle and slowly lower the vehicle over the
engine and transmission. It may be necessary to
move the engine/transmission assembly with the cra-
dle for clearance around body flanges.
(2) Align engine and transmission mounts to
attaching points. Install mounting bolts at the right
engine and left transmission mounts. Refer to proce-
dures outlined in this section.
(3) Slowly raise vehicle enough to remove the
engine dolly and cradle Special Tools 6135, 6710,
6848 and 6909.
(4) Remove Special tools 6912 and install bending
braces.
(5) Lower vehicle. Install generator and wiring
harness.
(6) Connect wiring harness on the front of the
engine.
(7) Install Air Conditioning Compressor.
(8) Install power steering pump and bracket and
accessory drive belt. Refer to Accessory drive Section
Located in group 7 for installation procedure.
(9) Raise vehicle and install axle shafts. Refer to
Group 3, Differential and Driveline for procedure.
(10) Install transmission and engine mount and
bracket assemblies. Refer to Engine Mounts section
of this Group.
(11)(AWD equipped)Install propeller shaft to
power transfer unit. Refer to Group 3, Differential
and Driveline for procedure.
(12) Connect exhaust system to manifold. Refer to
Group 11, Exhaust System and Intake Manifold for
procedure and torque specifications.
(13) Install crossmember cradle plate (Fig. 27).
(14) Install left and right inner splash shields.
(15) Connect automatic transmission shifter link-
age. Refer to Group 21, Transmission for procedures.
(16) Lower vehicle and connect fuel line and
heater hoses. Remove plugs from rear heater hoses
and install, if equipped.
(17) Install ground straps. Connect engine and
throttle body connections and harnesses.
(18) Connect throttle body linkage. Refer to Group
14, Fuel System for procedure.
(19) Install radiator and fan module assembly.
Install radiator hoses. Fill cooling system. See Group
7 for filling procedure.
(20) Install battery tray, battery and cover.
(21) Install air cleaner and hoses.
(22) Install oil filter. Fill engine crankcase with
proper oil to correct level.
(23) Start engine and run until operating temper-
ature is reached.
(24) Adjust transmission linkage, if necessary.
Fig. 28 Positioning Engine Cradle Support Post
MountsÐTypical
NS3.3/3.8L ENGINE 9 - 105
REMOVAL AND INSTALLATION (Continued)
(4) Remove upper intake manifold. Refer to Group
11, Exhaust System and Intake Manifolds for proce-
dure.
(5) Remove cylinder head covers and spark plugs.
(6) Remove electrical connector from ignition coils.
(7) Using suitable socket and flex handle at crank-
shaft pulley retaining screw, turn engine so the num-
ber 1 piston is at Top Dead Center on the
compression stroke.
(8) Remove rocker arms with rocker shaft and
install a dummy shaft. The rocker arms should not
be disturbed and left on shaft.
(9) With air hose attached to spark plug adapter
installed in number 1 spark plug hole, apply 90 to
100 psi air pressure (620.5 to 689 kPa). This is to
hold valves in place while servicing components.
(10) Using Tool C-4682 or equivalent, compress
valve spring and remove retainer valve locks and
valve spring.
(11) The intake valve stem seals should be pushed
firmly and squarely over the valve guide using the
valve stem as guide.Do Not Forceseal against top
of guide. When installing the valve retainer locks,
compress the springonly enoughto install the
locks.
CAUTION: Do not pinch seal between retainer and
top of valve guide.
(12) Follow the same procedure on the remaining 5
cylinders using the firing sequence 1-2-3-4-5-6.Make
sure piston in cylinder is at TDC on the valve
spring that is being covered.
(13) Remove spark plug adapter tool.
(14) Remove dummy shaft and install rocker shaft
assembly and tighten screws to 28 N´m (250 in. lbs.).
(15) Install cylinder head covers tighten screws to
14 N´m (120 in. lbs.) and electrical connector to igni-
tion coils.
(16) Install Intake Manifold. Refer to Group 11,
Exhaust System and Intake Manifold for procedure.
(17) Connect negative cable to battery.
CYLINDER HEAD COVER
REMOVAL
NOTE: The cylinder head cover can be either an
isolated type (Fig. 32) or a non-isolated type.
FRONT CYLINDER HEAD COVER
(1) Disconnect ignition cables from spark plugs.
(2) Disconnect crankcase vent hose from cylinder
head cover.
(3) Remove front cylinder head cover bolts.
(4) Remove cylinder head cover and gasket.REAR CYLINDER HEAD COVER
(1) Disconnect negative cable from battery.
(2) Remove Wiper Unit. Refer to Group 8K, Wind-
shield Wipers and Washers for procedure.
(3) Remove intake manifold upper plenum. Refer
to Group 11, Exhaust System and Intake Manifold
for procedure.
(4) Disconnect PCV hose from cylinder head cover.
(5) Remove rear cylinder head cover bolts
(6) Remove cylinder head cover and gasket.
INSTALLATION
FRONT CYLINDER HEAD COVER
(1) Clean cylinder head and cover mating surfaces.
Inspect cylinder head cover surface for flatness.
Replace gasket as necessary.
(2) Install cylinder head cover and bolts.
(3) Tighten cylinder head cover bolts to the follow-
ing specifications:
²Non±isolatedcylinder head cover to 12 N´m
(105 in. lbs.).
²Isolatedcylinder head cover to 10 N´m (90 in.
lbs.) (Fig. 32).
(4) Connect crankcase vent hose.
(5) Connect ignition cables to spark plugs.
REAR CYLINDER HEAD COVER
(1) Clean cylinder head and cover mating surfaces.
Inspect cylinder head cover surface for flatness.
Replace gasket as necessary.
(2) Install cylinder head cover and bolts.
(3) Tighten cylinder head cover bolts to the follow-
ing specifications:
Fig. 32 Cylinder Head CoverÐIsolated Type
NS3.3/3.8L ENGINE 9 - 107
REMOVAL AND INSTALLATION (Continued)
²Non±isolatedcylinder head cover to 12 N´m
(105 in. lbs.).
²Isolatedcylinder head cover to 10 N´m (90 in.
lbs.) (Fig. 32).
(4) Connect PCV hose from cylinder head cover.
(5) Install intake manifold upper plenum. Refer to
Group 11, Exhaust System and Intake Manifold for
procedure.
(6) Install Wiper Unit. Refer to Group 8K, Wind-
shield Wipers and Washers for procedure.
(7) Connect negative cable to battery.
CYLINDER HEAD
REMOVAL
(1) Drain cooling system. Refer to Group 7, Cooling
System for procedure and disconnect negative cable
from battery.
(2) Remove upper and lower intake manifolds.
Refer to Group 11, Exhaust System and Intake Man-
ifold.
WARNING: INTAKE MANIFOLD GASKET IS MADE
OF VERY THIN METAL AND MAY CAUSE PER-
SONAL INJURY, HANDLE WITH CARE.
(3) Disconnect coil wires, sending unit wire, heater
hoses and bypass hose.
(4) Remove PCV system hoses, evaporation control
system hose and cylinder head covers.
(5) Remove exhaust manifolds.
(6) Remove rocker arm and shaft assemblies.
Remove push rods andmark positions to ensure
installation in original locations.
(7) Remove the 9 head bolts from each cylinder
head and remove cylinder heads (Fig. 33).
INSTALLATION
(1) Clean all sealing surfaces of cylinder block and
cylinder heads.
(2) Install new gaskets on cylinder block (Fig. 34).
(3)The cylinder head bolts are torqued using
the torque yield method, they should be exam-
ined BEFORE reuse. If the threads are necked
down, the bolts should be replaced(Fig. 35).
(4) Necking can be checked by holding a scale or
straight edge against the threads. If all the threads
do not contact the scale the bolt should be replaced.
(5) Tighten the cylinder head bolts1-8inthe
sequence shown in (Fig. 33). Using the 4 step torque
turn method, tighten according to the following val-
ues:
²Step 1: Bolts1±8to61N´m(45ft.lbs.)
²Step 2: Bolts1±8to88N´m(65ft.lbs.)
²Step 3: Bolts1±8(again) to 88 N´m (65 ft. lbs.)
²Step 4: Bolts1±8turn an additional 1/4 Turn.
(Do not use a torque wrench for this step.)
NOTE: Bolt torque after 1/4 turn should be over 122
N´m (90 ft. lbs.). If not, replace the bolt.
(6) Tighten head bolt number 9 (Fig. 33) to 33 N´m
(25 ft. lbs.) after head bolts1±8have been tighten
to specifications.
Fig. 33 Cylinder Head Bolts Location and
Tightening Sequence
Fig. 34 Head Gasket Installation
Fig. 35 Checking Bolts for Stretching (Necking)
9 - 108 3.3/3.8L ENGINENS
REMOVAL AND INSTALLATION (Continued)
(3) Before removing valves,remove any burrs
from valve stem lock grooves to prevent dam-
age to the valve guides.Identify valves to insure
installation in original location.
VALVE INSTALLATION
(1) Coat valve stems with clean engine oil and
insert them in cylinder head.
(2) Check valve tip to spring seat dimensions A
after grinding the valve seats or faces. Grind valve
tip to give 49.541 to 51.271 mm (1.950 to 2.018 in.)
over spring seat when installed in the head (Fig. 41).
Check valve tip for scoring, if necessary, the tip
chamfer should be reground to prevent seal damage
when the valve is installed.
(3) Install valve spring seat spacer on head (Fig.
42).
(4) Install new cup seals on all valve stems and
over valve guides (Fig. 41). Install valve springs and
valve retainers (Fig. 42).
(5) Compress valve springs with Valve Spring
Compressor Tool C-3422-B, with adapter 6412 install
locks and release tool.If valves and/or seats are
reground, measure the installed height of
springs dimension B, make sure measurementsare taken from top of spring seat to the bottom
surface of spring retainer. If height is greater
than 1-19/32 inches, (40.6 mm), install a 1/32
inch (.794 mm) spacer in head counterbore to
bring spring height back to normal 1-17/32 to
1-19/32 inch (39.1 to 40.6 mm).TAPPET REMOVAL
(1) Refer to Cylinder Head Removal in this section.
Cylinder Head must be removed to gain access to
tappets for service.
(2) Remove yoke retainer and aligning yokes.
(3) Use Tool C-4129 to remove tappets from their
bores. If all tappets are to be removed, identify tap-
pets to insure installation in original location.
NOTE: If the tappet or bore in cylinder block is
scored, scuffed, or shows signs of sticking, ream
the bore to next oversize and replace with oversize
tappet.
CAUTION: The plunger and tappet bodies are not
interchangeable. The plunger and valve must
always be fitted to the original body. It is advisable
to work on one tappet at a time to avoid mixing of
parts. Mixed parts are not compatible. Do not disas-
semble a tappet on a dirty work bench.
INSTALLATION
(1) Lubricate tappets.
(2) Install tappets in their original positions.
(3) With roller tappets, install aligning yokes (Fig.
43).
(4) Install yoke retainer and torque screws to 12
N´m (105 in. lbs.) (Fig. 43).
(5) Install cylinder heads. Refer to cylinder head
installation of this section for procedure.
Fig. 40 Compress Valve Springs with Special Tool
C-3422-B with Adapter 6412
Fig. 41 Checking Valve Installed Height
Fig. 42 Valve Seal and SpringÐInstallation
9 - 110 3.3/3.8L ENGINENS
REMOVAL AND INSTALLATION (Continued)