
cause of low compression unless some malfunc-
tion is present.
(11) Clean or replace spark plugs as necessary
and adjust gap as specified in Group 8, Electrical.
Tighten to specifications.
(12) Test resistance of spark plug cables. Refer to
Group 8, Electrical Ignition System Secondary Cir-
cuit Inspection.
(13) Test coil output voltage, primary and second-
ary resistance. Replace parts as necessary. Refer to
Group 8, Electrical Ignition System.
(14) Check fuel pump pressure at idle and differ-
ent RPM ranges. Refer to Group 14, Fuel System for
Specifications.
(15) The air filter elements should be replaced as
specified in Group 0, Lubrication and Maintenance,.
(16) Inspect crankcase ventilation system as out
lined in Group 0, Lubrication and Maintenance. For
emission controls see Group 25, Emission Controls
for service procedures.
(17) Inspect and adjust accessory belt drives refer-
ring to Group 7, Cooling System, Accessory Drive
Belts for proper adjustments.
(18) Road test vehicle as a final test.
CYLINDER COMBUSTION PRESSURE LEAKAGE
TEST
The combustion pressure leakage test provides an
accurate means for determining engine condition.
Combustion pressure leakage testing will detect:
²Exhaust and intake valve leaks (improper seat-
ing).
²Leaks between adjacent cylinders or into water
jacket.
²Any causes for combustion/compression pressure
loss.
WARNING: DO NOT REMOVE THE RADIATOR CAP
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
Check the coolant level and fill as required. DO
NOT install the radiator cap.
Start and operate the engine until it attains nor-
mal operating temperature, then turn the engine
OFF.
Clean spark plug recesses with compressed air.
Remove the spark plugs.
Remove the oil filler cap.
Remove the air cleaner.
Calibrate the tester according to the manufactur-
er's instructions. The shop air source for testing
should maintain 483 kPa (70 psi) minimum, 1 379
kPa (200 psi) maximum and 552 kPa (80 psi) recom-
mended.Perform the test procedures on each cylinder
according to the tester manufacturer's instructions.
While testing, listen for pressurized air escaping
through the throttle body, tailpipe and oil filler cap
opening. Check for bubbles in the radiator coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage.
FOR EXAMPLE:At 552 kPa (80 psi) input pres-
sure, a minimum of 414 kPa (60 psi) should be main-
tained in the cylinder.
LASH ADJUSTER (TAPPET) NOISE DIAGNOSIS
A tappet-like noise may be produced from several
items. Check the following items.
(1) Engine oil level too high or too low. This may
cause aerated oil to enter the adjusters and cause
them to be spongy.
(2) Insufficient running time after rebuilding cylin-
der head. Low speed running up to 1 hour may be
required.
(3) During this time, turn engine off and let set for
a few minutes before restarting. Repeat this several
times after engine has reached normal operating
temperature.
(4) Low oil pressure.
(5) The oil restrictor pressed into the vertical oil
passage to the cylinder head is plugged with debris.
(6) Air ingested into oil due to broken or cracked
oil pump pick up.
(7) Worn valve guides.
(8) Rocker arm ears contacting valve spring
retainer.
(9) Rocker arm loose, adjuster stuck or at maxi-
mum extension and still leaves lash in the system.
(10) Faulty lash adjuster.
a. Check lash adjusters for sponginess while
installed in cylinder head. Depress part of rocker
arm over adjuster. Normal adjusters should feel very
firm. Spongy adjusters can be bottomed out easily.
b. Remove suspected lash adjusters, and disassem-
bleDo not reuse retainer caps. Do not inter-
change parts and make sure that care and
cleanliness is exercised in the handling of parts.
c. Clean out dirt and varnish with solvent.
d. Reassemble with engine oil.
e. Check for sponginess.
f. If still spongy, replace with new adjuster.
INSPECTION (ENGINE OIL LEAKS IN GENERAL)
Begin with a through 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.
9 - 8 ENGINENS
DIAGNOSIS AND TESTING (Continued)

CYLINDER HEAD COVER
REMOVAL
(1) Remove upper intake manifold. Refer to Group
11, Exhaust System and Intake Manifold.
(2) Remove nuts attaching front and rear intake
manifold supports from cylinder head cover attaching
studs.
(3) Remove ignition coil pack and plug wires (Fig.
28). Remove ground strap.
(4) Remove the cylinder head cover fasteners.
(5) Remove cylinder head cover from cylinder
head.
INSTALLATION
NOTE: Replace spark plug well seals when install-
ing a new cylinder head cover gasket.
(1) Clean all sealing surfaces.
(2) Install new cylinder head cover gaskets and
spark plug seals (Fig. 29).CAUTION: Do not allow oil or solvents to contact
the timing belt as they can deteriorate the rubber
and cause tooth skipping.
(3) Apply MopartSilicone Rubber Adhesive Seal-
ant at the camshaft cap corners and at the top edge
of the 1/2 round seal.
(4) Install cylinder head cover assembly to head
and tighten fasteners in sequence shown in (Fig. 30).
Using the 3 step torque method:
(a) Tighten all fasteners to 4.5 N´m (40 in. lbs.)
(b) Tighten all fasteners to 9.0 N´m (80 in. lbs.)
(c) Tighten all fasteners to 12 N´m (105 in. lbs.)
(5) Install ignition coil pack and plug wires.
Tighten fasteners to 12 N´m (105 in. lbs.).
(6) Install ground strap.
(7) Install front and rear intake manifold support
brackets and attaching nuts, but do not tighten at
this time.
(8) Install upper intake manifold. Refer to Group
11, Exhaust System and Intake Manifold for proce-
dure.
(9) Final torque intake manifold support nuts to
28 N´m (250 in. lbs.).
CAMSHAFT
REMOVAL
(1) Remove cylinder head cover using procedure
outlined in this section.
(2) Remove timing belt, sprockets and covers.
Refer to Timing Belt Service outlined in this section.
(3) Bearing caps are identified for location.
Remove the outside bearing caps first (Fig. 31).
(4) Loosen the camshaft bearing cap attaching
fasteners in sequence shown (Fig. 32) one camshaft
at a time.
CAUTION: Camshafts are not interchangeable. The
intake cam number 6 thrust bearing face spacing is
wider.
Fig. 28 Ignition Coil Pack and Ground Strap
Fig. 29 Cylinder Head Cover Gasket and Spark Plug
Seals
Fig. 30 Cylinder Head Cover Tightening Sequence
9 - 28 2.4L ENGINENS
REMOVAL AND INSTALLATION (Continued)

(2) Before installing the ring compressor, make
sure the oil ring expander ends are butted and the
rail gaps located as shown in (Fig. 92). As viewed
from top.
(3) Immerse the piston head and rings in clean
engine oil, slide the ring compressor, over the piston
(Fig. 93).Be sure position of rings does not
change during this operation.
(4) The directional stamp on the piston should
face toward the front of the engine (Fig. 90).
(5) Rotate crankshaft so that the connecting rod
journal is on the center of the cylinder bore. Insert
rod and piston assembly into cylinder bore and guide
rod over the crankshaft journal.
(6) Tap the piston down in cylinder bore, using a
hammer handle. At the same time, guide connecting
rod into position on connecting rod journal.
NOTE: The rod bearing bolts should not be reused.
(7) Before installing theNEWbolts the threads
should be coated with clean engine oil.(8) Install each bolt finger tight than alternately
torque each bolt to assemble the cap properly.
CAUTION: Do not use a torque wrench for second
part of last step.
(9) Tighten the bolts to 27 N´m PLUS 1/4 turn (20
ft. lbs. PLUS 1/4 turn).
(10) Using a feeler gauge, check connecting rod
side clearance (Fig. 94).
DISASSEMBLY AND ASSEMBLY
OIL PUMP
DISASSEMBLY
(1) To remove the relief valve, proceed as follows:
(a) Remove the threaded plug and gasket from
the oil pump (Fig. 95).
(b) Remove spring and relief valve.
(2) Remove oil pump cover screws, and lift off
cover.
(3) Remove pump rotors.
Fig. 92 Piston Ring End Gap Position
Fig. 93 PistonÐInstallation
Fig. 94 Checking Connecting Rod Side Clearance
Fig. 95 Oil Pressure Relief Valve
9 - 50 2.4L 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)

(6) Tap the piston down in cylinder bore, using a
hammer handle. At the same time, guide connecting
rod into position on connecting rod journal.
(7) The notch or groove on top of piston must be
pointing toward front of engine (Fig. 60).
(8) Install rod caps. Install nuts on cleaned and
oiled rod bolts and tighten nuts to 54 N´m (40 ft. lb.)
Plus 1/4 turn.
(9) Repeat procedure for each piston and rod
installation.
(10) Install cylinder heads and oil pan.
(11) Fill engine crankcase with proper oil to cor-
rect level.
(12) Connect negative cable to battery.
CRANKSHAFT
MAIN BEARINGS
Bearing caps are not interchangeable and should
be marked at removal to insure correct assembly
(Fig. 62). Upper and lower bearing halves are NOT
interchangeable. Lower main bearing halves of 1, 3
and 4 are interchangeable. Upper main bearing
halves of 1, 3 and 4 are interchangeable.
CRANKSHAFT MAIN JOURNALS
The crankshaft journals should be checked for
excessive wear, taper and scoring. (Fig. 61) Limits of
taper or out-of-round on any crankshaft journals
should be held to 0.025 mm (0.001 in.). Journal
grinding should not exceed 0.305 mm (0.012 in.)
under the standard journal diameter. Do NOT grind
thrust faces of Number 2 main bearing. Do NOT nick
crank pin or bearing fillets. After grinding, remove
rough edges from crankshaft oil holes and clean out
all passages.
CAUTION: With the nodular cast iron crankshafts
used it is important that the final paper or cloth pol-ish after any journal regrind be in the same direc-
tion as normal rotation in the engine.
Upper and lower Number 2 bearing halves are
flanged to carry the crankshaft thrust loads and are
NOT interchangeable with any other bearing halves
in the engine (Fig. 63). All bearing cap bolts removed
during service procedures are to be cleaned and oiled
before installation. Bearing shells are available in
standard and the following undersizes: 0.025 mm
(0.001 in.) and 0.254 mm (0.010 in). Never install an
undersize bearing that will reduce clearance below
specifications.
REMOVAL
(1) Remove oil pan and identify bearing caps
before removal.
(2) Remove bearing caps one at a time. Remove
upper half of bearing by inserting Special Main Bear-
ing Tool C-3059. (Fig. 64) into the oil hole of crank-
shaft.
Fig. 60 Piston I.D. NotchesFig. 61 Measure Crankshaft Journal O.D.
Fig. 62 Main Bearing Cap Identification
9 - 116 3.3/3.8L ENGINENS
REMOVAL AND INSTALLATION (Continued)

on the thrust direction. Staggering ring gap is impor-
tant for oil control.
PISTON AND ROD ÐINSTALLATION
(1) Before installing pistons and connecting rod
assemblies into the bore, be sure that compression
ring gaps are staggered so that neither is in line with
oil ring rail gap.
(2) Before installing the ring compressor, make
sure the oil ring expander ends are butted and the
rail gaps located as shown in (Fig. 80).
(3) Immerse the piston head and rings in clean
engine oil, slide the ring compressor, over the piston
(Fig. 81).Be sure position of rings does not
change during this operation.
(4) The weight stamp designation L or H will be in
the front half of the piston should face toward the
front of the engine for SOHC engine. The arrow
should face toward the front of the engine for DOHC
engine (Fig. 75).
(5) Rotate crankshaft so that the connecting rod
journal is on the center of the cylinder bore. Insertrod and piston assembly into cylinder bore and guide
rod over the crankshaft journal.
(6) Tap the piston down in cylinder bore, using a
hammer handle. At the same time, guide connecting
rod into position on connecting rod journal.
(7) Install rod caps. InstallNewbolts and tighten
to 27 N´m (20 ft.lb.) Plus 1/4 turn.
VIBRATION DAMPER
NOTE: If a gap is found in the crankshaft damper,
in the area where the Poly-V Generator belt rides
this is normal and is acceptable (Fig. 82).
REMOVAL
(1) Remove accessory drive belts. Refer to Group 7,
Cooling System for procedure outlined in that sec-
tion.
(2) Remove crankshaft damper bolt. Remove
damper using the large side of Special Tool 1026 and
insert 6827±A (Fig. 83).
Fig. 80 Piston Ring End Gap Position
Fig. 81 Installing Piston
Fig. 82 Weld Gap
Fig. 83 Crankshaft DamperÐRemoval
9 - 28 ENGINENS/GS
REMOVAL AND INSTALLATION (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)

(36) Operate the engine with the radiator cap off.
Inspect for leaks and continue operating the engine
until the thermostat opens. Add coolant, if required.
VALVES AND VALVE SPRINGSÐHEAD OFF
This procedure is done with the engine cylinder
head removed from the block.
REMOVAL
(1) Remove the engine cylinder head from the cyl-
inder block. Refer to cylinder head removal in this
section.
(2) Use Valve Spring Compressor Tool and com-
press each valve spring.
(3) Remove the valve locks, retainers, and springs.
(4) Use an Arkansas smooth stone or a jewelers
file to remove any burrs on the top of the valve stem,
especially around the groove for the locks.
(5) Remove the valves, and place them in a rack in
the same order as removed.
INSTALLATION
(1) Fit each valve to its respective valve guide.
NOTE: If valves and valve seats have been refaced
refer to Service Procedures in this section. Follow
The Valve Stand Down procedure.
(2) Install lower, washer and spring.
(3) Install upper spring collar, and compress valve
spring with spring compressor tool. Install split cone
retainers.
HYDRAULIC TAPPETS
REMOVAL
(1) Remove coolant pressure bottle.
(2) Remove cylinder head cover. Refer to cylinder
head cover removal in this section.
(3) Remove rocker assembly and push rods. Iden-
tify push rods to ensure installation in original loca-
tion (Fig. 34).
(4) Remove cylinder head, intake manifold, and
exhaust manifold. Refer to cylinder head removal in
this section.
(5) Remove yoke retainer and aligning yokes (Fig.
35).
(6) Slide Hydraulic Tappet Remover/Installer Tool
through opening in block and seat tool firmly in the
head of tappet.
(7) Pull tappet out of bore with a twisting motion.
If all tappets are to be removed, identify tappets to
ensure installation in original location.
(8) 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.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 dis-
assemble a tappet on a dirty work bench.
INSTALLATION
(1) Lubricate tappets.
(2) Install tappets and yoke retainers in their orig-
inal positions. Ensure that the oil feed hole in the
side of the tappet body faces up (away from the
crankshaft).
Fig. 34 Tappet and Rocker Arm Assembly
Fig. 35 Tappet and Yoke
9 - 60 ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)