2002 JEEP LIBERTY 3.7 head bolts

INTAKE MANIFOLD
DESCRIPTION
The intake manifold (Fig. 86) is made of a compos-
ite material and features 300 mm (11.811 in.) long
runners which maximizes low end torque. The intake
manifold uses single plane sealing which consist of
six individual press in place port gaskets to prevent
leaks. The throttle body attaches directly to the
intake manifold. Eight studs and two bolts are used
to fasten the intake to the head.
DIAGNOSIS AND TESTING - INTAKE
MANIFOLD LEAKS
An intake manifold air leak is characterized by
lower than normal manifold vacuum. Also, one or
more cylinders may not be functioning.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR THE FAN.
DO NOT WEAR LOOSE CLOTHING.
(1) Start the engine.
(2) Spray a small stream of water (Spray Bottle) at
the suspected leak area.
(3) If engine RPM'S change, the area of the sus-
pected leak has been found.
(4) Repair as required.
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove resonator assembly and air inlet hose.
(3) Disconnect throttle and speed control cables.
(4) Disconnect electrical connectors for the follow-
ing components: Refer to FUEL SYSTEM for compo-
nent locations.
²Manifold Absolute Pressure (MAP) Sensor
²Intake Air Temperature (IAT) Sensor
²Throttle Position (TPS) Sensor
²Coolant Temperature (CTS) Sensor
²Idle Air Control (IAC) Motor
(5) Disconnect vapor purge hose, brake booster
hose, speed control servo hose, positive crankcase
ventilation (PCV) hose.
(6) Disconnect generator electrical connections.
(7) Disconnect air conditioning compressor electri-
cal connections.
(8) Disconnect left and right radio suppressor
straps.
(9) Disconnect and remove ignition coil towers.
(10) Remove top oil dipstick tube retaining bolt
and ground strap.
Fig. 85 Oil Pump and Primary Timing Chain
Tensioner Tightening Sequence
Fig. 86 INTAKE MANIFOLD
1 - THROTTLE BODY
2 - INTAKE MANIFOLD
3 - INTAKE PORT GASKETS
9 - 68 ENGINE - 3.7LKJ
OIL PUMP (Continued)

(11) Bleed fuel system. Refer to FUEL SYSTEM.
(12) Remove fuel rail.
(13) Remove throttle body assembly and mounting
bracket.
(14) Drain cooling system below coolant tempera-
ture level. Refer to COOLING SYSTEM.
(15) Remove the heater hoses from the engine
front cover and the heater core.
(16) Unclip and remove heater hoses and tubes
from intake manifold.
(17) Remove coolant temperature sensor. Refer to
FUEL SYSTEM.
(18) Remove intake manifold retaining fasteners in
reverse order of tightening sequence.
(19) Remove intake manifold.
INSTALLATION
(1) Install intake manifold gaskets.
(2) Install intake manifold.
(3) Install intake manifold retaining bolts and
tighten in sequence shown in to 12 N´m (105 in. lbs.).
(4) Install left and right radio suppressor straps.
(5) Install throttle body assembly.
(6) Install throttle cable bracket.
(7) Connect throttle cable and speed control cable
to throttle body.
(8) Install fuel rail.
(9) Install ignition coil towers.
(10) Position and install heater hoses and tubes
onto intake manifold.
(11) Install the heater hoses to the heater core and
engine front cover.
(12) Connect electrical connectors for the following
components:
²Manifold Absolute Pressure (MAP) Sensor
²Intake Air Temperature (IAT) Sensor
²Throttle Position (TPS) Sensor
²Coolant Temperature (CTS) Sensor
²Idle Air Control (IAC) Motor
²Ignition coil towers
²Fuel injectors
(13) Install top oil dipstick tube retaining bolt and
ground strap.
(14) Connect generator electrical connections.
(15) Connect Vapor purge hose, Brake booster
hose, Speed control servo hose, Positive crankcase
ventilation (PCV) hose.
(16) Fill cooling system.
(17) Install resonator assembly and air inlet hose.
(18) Connect negative cable to battery.
EXHAUST MANIFOLD
DESCRIPTION
The exhaust manifolds (Fig. 87) are log style with
a patented flow enhancing design to maximize perfor-
mance. The exhaust manifolds are made of high sili-
con molybdenum cast iron. A perforated core graphite
exhaust manifold gasket is used to improve sealing
to the cylinder head. The exhaust manifolds are cov-
ered by a three layer laminated heat shield for ther-
mal protection and noise reduction. The heat shields
(Fig. 88) are fastened with a torque prevailing nut
that is backed off slightly to allow for the thermal
expansion of the exhaust manifold.
REMOVAL
RIGHT EXHAUST MANIFOLD
(1) Disconnect the negative cable from the battery.
(2) Raise and support the vehicle.
(3) Remove the bolts and nuts attaching the
exhaust pipe to the engine exhaust manifold.
(4) Lower the vehicle.
(5) Remove the exhaust heat shield (Fig. 89).
(6) Remove bolts, nuts and washers attaching
manifold to cylinder head.
(7) Remove manifold and gasket from the cylinder
head.
Fig. 87 EXHAUST MANIFOLDS
1 - LEFT SIDE EXHAUST MANIFOLD
2 - RIGHT SIDE EXHAUST MANIFOLD
KJENGINE - 3.7L 9 - 69
INTAKE MANIFOLD (Continued)

LEFT EXHAUST MANIFOLD
(1) Disconnect the negative cable from the battery.
(2) Raise and support the vehicle.
(3) Remove the bolts and nuts attaching the
exhaust pipe to the engine exhaust manifold.
(4) Lower the vehicle.
(5) Remove the exhaust heat shields (Fig. 90).
(6) Remove bolts, nuts and washers attaching
manifold to cylinder head.
(7) Remove manifold and gasket from the cylinder
head.
INSTALLATION
RIGHT EXHAUST MANIFOLD
CAUTION: If the studs came out with the nuts when
removing the engine exhaust manifold, install new
studs. Apply sealer on the coarse thread ends.
Water leaks may develop at the studs if this precau-
tion is not taken.
Fig. 88 EXHAUST MANIFOLD HEAT SHIELDS
1 - RIGHT SIDE EXHAUST MANIFOLD HEAT SHIELD
2 - RIGHT SIDE EXHAUST MANIFOLD FLANGE
3 - LEFT SIDE EXHAUST MANIFOLD HEAT SHIELD
2 - LEFT SIDE EXHAUST MANIFOLD FLANGE
Fig. 89 EXHAUST MANIFOLD RIGHT
1 - Heat Shield
2 - Nuts
3 - Manifold Flange
Fig. 90 EXHAUST MANIFOLD LEFT
1 - Heat Shield
2 - Nuts
3 - Manifold Flange
9 - 70 ENGINE - 3.7LKJ
EXHAUST MANIFOLD (Continued)

(1) Position the engine exhaust manifold and gas-
ket on the two studs located on the cylinder head.
Install conical washers and nuts on these studs.
(2) Install remaining conical washers. Starting at
the center arm and working outward, tighten the
bolts and nuts to 25 N´m (18 ft. lbs.) torque.
(3) Install the exhaust heat shields.
(4) Raise and support the vehicle.
CAUTION: Over tightening heat shield fasteners,
may cause shield to distort and/or crack.
(5) Assemble exhaust pipe to manifold and secure
with bolts, nuts and retainers. Tighten the bolts and
nuts to 34 N´m (25 ft. lbs.) torque.
LEFT EXHAUST MANIFOLD
CAUTION: If the studs came out with the nuts when
removing the engine exhaust manifold, install new
studs. Apply sealer on the coarse thread ends.
Water leaks may develop at the studs if this precau-
tion is not taken.
(1) Position the engine exhaust manifold and gas-
ket on the two studs located on the cylinder head.
Install conical washers and nuts on these studs.
(2) Install remaining conical washers. Starting at
the center arm and working outward, tighten the
bolts and nuts to 25 N´m (18 ft. lbs.) torque.
(3) Install the exhaust heat shields.
(4) Raise and support the vehicle.
CAUTION: Over tightening heat shield fasteners,
may cause shield to distort and/or crack.
(5) Assemble exhaust pipe to manifold and secure
with bolts, nuts and retainers. Tighten the bolts and
nuts to 34 N´m (25 ft. lbs.) torque.
VALVE TIMING
DESCRIPTION
The timing drive system has been designed to pro-
vide quiet performance and reliability to support a
non-free wheelingengine. Specifically the intake
valves are non-free wheeling and can be easily dam-
aged with forceful engine rotation if camshaft-to-
crankshaft timing is incorrect. The timing drive
system consists of a primary chain, two secondary
timing chain drives and a counterbalance shaft drive.
OPERATION
The primary timing chain is a single inverted tooth
chain type. The primary chain drives the large 40
tooth idler sprocket directly from a 20 tooth crank-shaft sprocket. Primary chain motion is controlled by
a pivoting leaf spring tensioner arm and a fixed
guide. The arm and the guide both use nylon plastic
wear faces for low friction and long wear. The pri-
mary chain receives oil splash lubrication from the
secondary chain drive and designed oil pump leak-
age. The idler sprocket assembly connects the pri-
mary chain drive, secondary chain drives, and the
counterbalance shaft. The idler sprocket assembly
consists of two integral 26 tooth sprockets a 40 tooth
sprocket and a helical gear that is press-fit to the
assembly. The spline joint for the 40 tooth sprocket is
a non ± serviceable press fit anti rattle type. A spiral
ring is installed on the outboard side of the fifty
tooth sprocket to prevent spline disengagement. The
idler sprocket assembly spins on a stationary idler
shaft. The idler shaft is a light press-fit into the cyl-
inder block. A large washer on the idler shaft bolt
and the rear flange of the idler shaft are used to con-
trol sprocket thrust movement. Pressurized oil is
routed through the center of the idler shaft to pro-
vide lubrication for the two bushings used in the
idler sprocket assembly.
There are two secondary drive chains, both are
roller type, one to drive the camshaft in each SOHC
cylinder head. There are no shaft speed changes in
the secondary chain drive system. Each secondary
chain drives a 26 tooth cam sprocket directly from
the 26 tooth sprocket on the idler sprocket assembly.
A fixed chain guide and a hydraulic oil damped ten-
sioner are used to maintain tension in each second-
ary chain system. The hydraulic tensioners for the
secondary chain systems are fed pressurized oil from
oil reservoir pockets in the block. Each tensioner
incorprates a controled leak path through a device
known as a vent disc located in the nose of the piston
to manage chain loads. Each tensioner also has a
mechanical ratchet system that limits chain slack if
the tensioner piston bleeds down after engine shut
down. The tensioner arms and guides also utilize
nylon wear faces for low friction and long wear. The
secondary timing chains receive lubrication from a
small orifice in the tensioners. This orifice is pro-
tected from clogging by a fine mesh screen which is
located on the back of the hydraulic tensioners.
STANDARD PROCEDURE
MEASURING TIMING CHAIN WEAR
NOTE: This procedure must be performed with the
timing chain cover removed.
(1) Remove the timing chain cover. Refer to Timing
Chain Cover in this section for procedure.
KJENGINE - 3.7L 9 - 71
EXHAUST MANIFOLD (Continued)

CAUTION: Care should be taken not to damage
camshaft target wheel. Do not hold target wheel
while loosening or tightening camshaft sprocket.
Do not place the target wheel near a magnetic
source of any kind. A damaged or magnetized tar-
get wheel could cause a vehicle no start condition.
CAUTION: Do not forcefully rotate the camshafts or
crankshaft independently of each other. Damaging
intake valve to piston contact will occur. Ensure
negative battery cable is disconnected to guard
against accidental starter engagement.
(13) Remove left and right camshaft sprocket bolts.
(14) While holding the left camshaft steel tube
with Special Tool 8428 Camshaft Wrench, remove the
left camshaft sprocket. Slowly rotate the camshaft
approximately 5 degrees clockwise to a neutral posi-
tion.
(15) While holding the right camshaft steel tube
with Special Tool 8428 Camshaft Wrench, remove the
right camshaft sprocket.
(16) Remove idler sprocket assembly bolt.
(17) Slide the idler sprocket assembly and crank
sprocket forward simultaneously to remove the pri-
mary and secondary chains.
(18) Remove both pivoting tensioner arms and
chain guides.
(19) Remove chain tensioner.
INSPECTION
Inspect the following components:
²Sprockets for excessive tooth wear. Some tooth
markings are normal and not a cause for sprocket
replacement.
²Idler sprocket assembly bushing and shaft for
excessive wear.
²Idler sprocket assembly spline joint. The joint
should be tight with no backlash or axial movement.
²Chain guides and tensioner arms. Replace these
parts if grooving in plastic face is more than 1 mm
(0.039 in.) deep. If plastic face is severely grooved or
melted, the tensioner lube jet may be clogged. The
tensioner should be replaced.
²Secondary chain tensioner piston and ratcheting
device. Inspect for evidence of heavy contact between
tensioner piston and tensioner arm. If this condition
exist the tensioner tensioner arm and chain should
be replaced.
²Primary chain tensioner plastic faces. Replace as
required.
Fig. 105 CAMSHAFT POSITION SENSOR
1 - CYLINDER HEAD
2 - CAMSAHFT POSITION SENSOR
2 - SCREW
Fig. 106 Crankshaft Position Sensor
1 - CRANKSHAFT POSITION SENSOR
2 - CYLINDER HEAD COVER
3 - CAMSHAFT POSITION SENSOR
4 - RIGHT SIDE CYLINDER BLOCK
KJENGINE - 3.7L 9 - 79
TIMING BELT/CHAIN AND SPROCKET(S (Continued)

INSTALLATION
(1) Using a vise, lightly compress the secondary
chain tensioner piston until the piston step is flush
with the tensioner body. Using a pin or suitable tool,
release ratchet pawl by pulling pawl back against
spring force through access hole on side of tensioner.
While continuing to hold pawl back, Push ratchet
device to approximately 2 mm from the tensioner
body. Install Special Tool 8514 lock pin into hole on
front of tensioner (Fig. 107). Slowly open vise to
transfer piston spring force to lock pin.
(2) Position primary chain tensioner over oil pump
and insert bolts into lower two holes on tensioner
bracket. Tighten bolts to 28 N´m (250 in. lbs.).
(3) Install right side chain tensioner arm. Apply
MopartLock N, Seal to torxtbolt, tighten bolt to 28
N´m (250 in. lbs.).
CAUTION: The silver bolts retain the guides to the
cylinder heads and the black bolts retain the guides
to the engine block.
(4) Install the left side chain guide. Tighten the
bolts to 28 N´m (250 in. lbs.).
(5) Install left side chain tensioner arm. Apply
MopartLock N, Seal to torxtbolt, tighten bolt to 28
N´m (250 in. lbs.).(6) Install the right side chain guide. Tighten the
bolts to 28 N´m (250 in. lbs.).
(7) Install both secondary chains onto the idler
sprocket. Align two plated links on the secondary
chains to be visible through the two lower openings
on the idler sprocket (4 o'clock and 8 o'clock). Once
the secondary timing chains are installed, position
special tool 8429 to hold chains in place for installa-
tion.
(8) Align primary chain double plated links with
the timing mark at 12 o'clock on the idler sprocket.
Align the primary chain single plated link with the
timing mark at 6 o'clock on the crankshaft sprocket.
(9) Lubricate idler shaft and bushings with clean
engine oil.
NOTE: The idler sprocket must be timed to the
counterbalance shaft drive gear before the idler
sprocket is fully seated.
(10) Install all chains, crankshaft sprocket, and
idler sprocket as an assembly (Fig. 108). After guid-
ing both secondary chains through the block and cyl-
inder head openings, affix chains with a elastic strap
or the equivalent, This will maintain tension on
chains to aid in installation. Align the timing mark
on the idler sprocket to the timing mark on the coun-
terbalance shaft drive gear, then seat idler sprocket
fully (Fig. 109). Before installing idler sprocket bolt,
lubricate washer with oil, and tighten idler sprocket
assembly retaining bolt to 34 N´m (25 ft. lbs.).
Fig. 107 Resetting Secondary Chain Tensioners
1 - VISE
2 - INSERT LOCK PIN
3 - RATCHET PAWL
4 - RATCHET
5 - PISTON
Fig. 108 Installing Idler Gear, Primary and
Secondary Timing Chains
1 - SPECIAL TOOL 8429
2 - PRIMARY CHAIN IDLER SPROCKET
3 - CRANKSHAFT SPROCKET
9 - 80 ENGINE - 3.7LKJ
TIMING BELT/CHAIN AND SPROCKET(S (Continued)

NOTE: It will be necessary to slightly rotate cam-
shafts for sprocket installation.
(11) Align left camshaft sprocket ªLº dot to plated
link on chain.
(12) Align right camshaft sprocket ªRº dot to
plated link on chain.
CAUTION: Remove excess oil from the camshaft
sprocket bolt. Failure to do so can result in over-
torque of bolt resulting in bolt failure.
(13) Remove Special Tool 8429, then attach both
sprockets to camshafts. Remove excess oil from bolts,
then Install sprocket bolts, but do not tighten at this
time.
(14) Verify that all plated links are aligned with
the marks on all sprockets and the ªV6º marks on
camshaft sprockets are at the 12 o'clock position.
CAUTION: Ensure the plate between the left sec-
ondary chain tensioner and block is correctly
installed.
(15) Install both secondary chain tensioners.
Tighten bolts to 28 N´m (250 in. lbs.).
NOTE: Left and right secondary chain tensioners
are not common.(16) Remove all locking pins (3) from tensioners.
CAUTION: After pulling locking pins out of each
tensioner, DO NOT manually extend the tensioner(s)
ratchet. Doing so will over tension the chains,
resulting in noise and/or high timing chain loads.
(17) Using Special Tool 6958, Spanner with Adap-
tor Pins 8346, tighten left (Fig. 110) and right (Fig.
111). camshaft sprocket bolts to 122 N´m (90 ft. lbs.).
(18) Rotate engine two full revolutions. Verify tim-
ing marks are at the follow locations:
²primary chain idler sprocket dot is at 12 o'clock
²primary chain crankshaft sprocket dot is at 6
o'clock
²secondary chain camshaft sprockets ªV6º marks
are at 12 o'clock
²counterbalancer shaft drive gear dot is aligned
to the idler sprocket gear dot
(19) Lubricate all three chains with engine oil.
Fig. 109 COUNTERBALANCE SHAFT ALIGNMENT
MARKS
1 - COUNTERBALANCE SHAFT
2 - TIMING MARKS
3 - IDLER SPROCKET
Fig. 110 Tightening Left Side Camshaft Sprocket
Bolt
1 - TORQUE WRENCH
2 - CAMSHAFT SPROCKET
3 - LEFT CYLINDER HEAD
4 - SPECIAL TOOL 6958 SPANNER WITH ADAPTER PINS 8346
KJENGINE - 3.7L 9 - 81
TIMING BELT/CHAIN AND SPROCKET(S (Continued)

Remove all gasket material from cylinder head and
block (Refer to 9 - ENGINE - STANDARD PROCE-
DURE). Be careful not to gouge or scratch the alumi-
num head sealing surface.
Clean all engine oil passages.
INSPECTION
(1) Cylinder head must be flat within 0.1 mm
(0.004 in.) (Fig. 6).
(2) Inspect camshaft bearing journals for scoring.
(3) Remove carbon and varnish deposits from
inside of valve guides with a reliable guide cleaner.
(4) Using a small hole gauge and a micrometer,
measure valve guides in 3 places top, middle and bot-
tom (Fig. 7). (Refer to 9 - ENGINE - SPECIFICA-
TIONS) Replace guides if they are not within
specification.
(5) Check valve guide height (Fig. 8).
INSTALLATION - CYLINDER HEAD
NOTE: The Cylinder head bolts should be examined
BEFORE reuse. If the threads are necked down, the
bolts must be replaced (Fig. 9).
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.
(1) Before installing the bolts, the threads should
be coated with engine oil.
(2) Position cylinder head gasket on engine block
(Fig. 10).
(3) Install cylinder head on engine block.
(4) Tighten the cylinder head bolts in the sequence
shown in (Fig. 11). Using the 4 step torque turn
method, tighten according to the following values:
²First All to 34 N´m (25 ft. lbs.)
²Second All to 68 N´m (50 ft. lbs.)
Fig. 6 Checking Cylinder Head Flatness
1 - FEELER GAUGE
2 - STRAIGHT EDGE
Fig. 7 Checking Wear on Valve GuideÐTypical
1-TOP
2 - MIDDLE
3 - BOTTOM
4 - CUT AWAY VIEW OF VALVE GUIDE MEASUREMENT
LOCATIONS
Fig. 8 Valve Guide Height
1 - VALVE GUIDE
2 - 13.25 - 13.75 MM (.521 - .541 IN.)
3 - SPRING SEAT
Fig. 9 Checking Bolts for Stretching (Necking)
1 - STRETCHED BOLT
2 - THREADS ARE NOT STRAIGHT ON LINE
3 - THREADS ARE STRAIGHT ON LINE
4 - UNSTRETCHED BOLT
KJENGINE9s-21
CYLINDER HEAD (Continued)