1995 JEEP YJ battery

CONNECTING ROD BEARING CLEARANCE
Engine connecting rod bearing clearances can be
determined by use of Plastigage, or equivalent. The
following is the recommended procedures for the use
of Plastigage:
(1) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(2) Place a piece of Plastigage across the entire width
of the bearing cap shell (Fig. 2). Position the Plastigage
approximately 6.35 mm (1/4 inch) off center and away
from the oil holes. In addition, suspect areas can be
checked by placing the Plastigage in the suspect area.
(3) The crankshaft must be turned until the connect-
ing rod to be checked starts moving toward the top of
the engine. Only then should the rod cap with Plasti-
gage in place be assembled. Tighten the rod cap nut to
45 Nzm (33 ft. lbs.) torque.DO NOT rotate the crank-
shaft or the Plastigage may be smeared, giving in-
accurate results.
(4) Remove the bearing cap and compare the width
of the flattened Plastigage with the scale provided on
the package (Fig. 3). Plastigage generally comes in 2
scales (one scale is in inches and the other is a met-
ric scale). Locate the band closest to the same width.
This band shows the amount of clearance. Differ-
ences in readings between the ends indicate the
amount of taper present. Record all readings taken
(refer to Engine Specifications).
(5) Plastigage is available in a variety of clearance
ranges. The 0.025-0.076 mm (0.001-0.003 inch) range
is usually the most appropriate for checking engine
bearing clearances.
REPAIR DAMAGED OR WORN THREADS
Damaged or worn threads can be repaired. Essen-
tially, this repair consists of:
²Drilling out worn or damaged threads.
²Tapping the hole with a special Heli-Coil Tap, or
equivalent.
²Installing an insert into the tapped hole.
This brings the hole back to its original thread
size.
CAUTION: Be sure that the tapped holes maintain
the original center line.Heli-Coil tools and inserts are readily available
from automotive parts jobbers.
SERVICE ENGINE ASSEMBLY (SHORT BLOCK)
A service replacement engine assembly (short
block) may be installed whenever the original cylin-
der block is defective or damaged beyond repair. It
consists of the cylinder block, crankshaft, piston and
rod assemblies. If needed, the camshaft must be pro-
cured separately and installed before the engine is
installed in the vehicle.
A short block is identified with the letter ``S'' stamped
on the same machined surface where the build date
code is stamped for complete engine assemblies.
Installation includes the transfer of components
from the defective or damaged original engine. Fol-
low the appropriate procedures for cleaning, inspec-
tion and torque tightening.
HYDROSTATIC LOCK
When an engine is suspected of hydrostatic lock
(regardless of what caused the problem), follow the
steps below.
(1) Perform the Fuel Pressure Release Procedure
(refer to Group 14, Fuel System).
(2) Disconnect the negative cable from the battery.
(3) Inspect air cleaner, induction system and in-
take manifold to ensure system is dry and clear of
foreign material.
(4) Place a shop towel around the spark plugs to
catch any fluid that may possibly be under pressure in
the cylinder head. Remove the plugs from the engine.
CAUTION: DO NOT use the starter motor to rotate
the crankshaft. Severe damage could occur.
(5) With all spark plugs removed, rotate the crank-
shaft using a breaker bar and socket.
(6) Identify the fluid in the cylinders (i.e. coolant,
fuel, oil, etc.).
(7) Make sure all fluid has been removed from the
cylinders.
(8) Repair engine or components as necessary to
prevent this problem from occurring again.
(9) Squirt engine oil into the cylinders to lubricate
the walls. This will prevent damage on restart.
(10) Install new spark plugs. Tighten the spark
plugs to 37 Nzm (27 ft. lbs.) torque.
(11) Drain engine oil. Remove and discard the oil
filter.
(12) Install the drain plug. Tighten the plug to 34
Nzm (25 ft. lbs.) torque.
(13) Install a new oil filter.
(14) Fill engine crankcase with the specified
amount and grade of oil (refer to Group 0, Lubrica-
tion and Maintenance).
(15) Connect the negative cable to the battery.
(16) Start the engine and check for any leaks.
Fig. 3 Clearance Measurement
9 - 4 ENGINESJ

ENGINE DIAGNOSIS
Engine diagnosis is helpful in determining the
causes of malfunctions not detected and remedied by
routine tune-ups.
These malfunctions may be classified as either per-
formance (e.g., engine idles rough and stalls) or me-
chanical (e.g., a strange noise).
Refer to the Service DiagnosisÐPerformance chart
and the Service DiagnosisÐMechanical chart for pos-
sible causes and corrections of malfunctions. Refer to
Group 14, Fuel System for the fuel system diagnosis.
GENERAL INFORMATION
Additional tests and diagnostic procedures may be
necessary for specific engine malfunctions that can
not be isolated with the Service Diagnosis charts. In-
formation concerning additional tests and diagnosis
is provided within the following diagnosis:
²Cylinder Compression Pressure Test.
²Cylinder Combustion Pressure Leakage Test.
²Engine Cylinder Head Gasket Failure Diagnosis.
²Intake Manifold Leakage Diagnosis.
INTAKE MANIFOLD LEAKAGE DIAGNOSIS
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 DI-
RECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR THE FAN.
DO NOT WEAR LOOSE CLOTHING.
METHOD 1
(1) Start the engine.
(2) Spray a small stream of water at the suspected
leak area.
(3) If a change in RPM'S, the area of the suspected
leak has been found.
(4) Repair as required.
CYLINDER COMPRESSION PRESSURE TEST
The results of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
Ensure the battery is completely charged and the
engine starter motor is in good operating condition.
Otherwise the indicated compression pressures may
not be valid for diagnosis purposes.
(1) Clean the spark plug recesses with compressed
air.
(2) Remove the spark plugs.
(3) Secure the throttle in the wide-open position.
(4) Disconnect the ignition coil.(5) Insert a compression pressure gauge and rotate
the engine with the engine starter motor for three
revolutions.
(6) Record the compression pressure on the 3rd
revolution. Continue the test for the remaining cylin-
ders.
Refer to Engine Specifications for the correct en-
gine compression pressures.
ENGINE CYLINDER HEAD GASKET FAILURE
DIAGNOSIS
A leaking engine cylinder head gasket usually re-
sults in loss of power, loss of coolant and engine mis-
firing.
An engine cylinder head gasket leak can be located
between adjacent cylinders or between a cylinder and
the adjacent water jacket.
²An engine cylinder head gasket leaking between
adjacent cylinders is indicated by a loss of power
and/or engine misfire.
²An engine cylinder head gasket leaking between a
cylinder and an adjacent water jacket is indicated by
coolant foaming or overheating and loss of coolant.
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine if an engine cylinder head gasket is
leaking between adjacent cylinders; follow the proce-
dures outlined in Cylinder Compression Pressure
Test. An engine cylinder head gasket leaking between
adjacent cylinders will result in approximately a 50-
70% reduction in compression pressure.
CYLINDER-TO-WATER JACKET LEAKAGE
TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A DI-
RECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR THE FAN.
DO NOT WEAR LOOSE CLOTHING.
Remove the radiator cap.
Start the engine and allow it to warm up until the
engine thermostat opens.
If a large combustion/compression pressure leak ex-
ists, bubbles will be visible in the coolant.
If bubbles are not visible, install a radiator pres-
sure tester and pressurize the coolant system.
If a cylinder is leaking combustion pressure into
the water jacket, the tester pointer will pulsate with
every combustion stroke of the cylinder.
JENGINES 9 - 5

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.
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 ac-
cording 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.
Refer to the Cylinder Combustion Pressure Leak-
age Test Diagnosis chart.
INSPECTION (ENGINE OIL LEAKS IN GENERAL)
Begin with a through visual inspection of the en-
gine, particularly at the area of the suspected leak. If
an oil leak source is not readily identifiable, the fol-
lowing 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.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for ap-
proximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified, re-
pair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24km (15 miles), and
repeat step (3).
If the oil leak source is not positively identi-
fied at this time, proceed with the air leak detec-
tion test method as follows:
(1) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(2) Remove the PCV valve from the cylinder head
cover. Cap or plug the PCV valve grommet.
(3) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
(4) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is de-
tected and identified, repair per service manual pro-
cedures.
(5) If the leakage occurs at the rear oil seal area,
refer to the section, Inspection for Rear Seal Area
Leak.
(6) If no leaks are detected, turn off the air supply
and remove the air hose and all plugs and caps. In-
stall the PCV valve and breather cap hose. Proceed
to step 7.
(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the en-
gine, a more involved inspection is necessary. The fol-
lowing steps should be followed to help pinpoint the
source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak:
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, distributor seal,
camshaft bore cup plugs oil galley pipe plugs, oil
9 - 6 ENGINESJ

The digits of the code identify:
(1) 1st DigitÐThe year (4 = 1994).
(2) 2nd & 3rd DigitsÐThe month (01 - 12).
(3) 4th & 5th DigitsÐThe engine type/fuel system/
compression ratio (HX = A 2.5 liter (150 CID) 9.1:1
compression ratio engine with a multi-point fuel in-
jection system).
(4) 6th & 7th DigitsÐThe day of engine build (01 -
31).
FOR EXAMPLE:Code * 401HX23 * identifies a
2.5 liter (150 CID) engine with a multi-point fuel in-
jection system, 9.1:1 compression ratio and built on
January 23, 1994.
OVERSIZE AND UNDERSIZE COMPONENT
CODES
Some engines may be built with oversize or under-
size components such as:
²Oversize cylinder bores.
²Oversize camshaft bearing bores.
²Undersize crankshaft main bearing journals.
²Undersize connecting rod journals.
These engines are identified by a letter code (Fig.
4) stamped on the oil filter boss near the distributor
(Fig. 5).
ENGINE MOUNTSÐFRONT
The front mounts support the engine at each side.
These supports are made of resilient rubber.
REMOVALÐXJ VEHICLES
(1) Disconnect negative cable from battery.
(2) Raise the vehicle.
(3) Support the engine.
(4) Remove through bolt nut (Fig. 6). DO NOT re-
move the through bolt.
(5) Remove the retaining bolts and nuts from the
support cushions (Fig. 6).
(6) Remove the through bolt.
(7) Remove the support cushions.
INSTALLATIONÐXJ VEHICLES
(1) If the engine support bracket was removed, po-
sition the LEFT bracket (Fig. 6) and the RIGHT
bracket with generator brace (Fig. 7) onto the cylin-
der block. Install the bolts and stud nuts.
(a) RIGHT SIDE (Fig. 7)ÐTighten the bolts to 61
Nzm (45 ft. lbs.) torque. Tighten the stud nuts to 46
Nzm (34 ft. lbs.) torque.
(b) LEFT SIDE (Fig. 6)ÐTighten the bolts to 61
Nzm (45 ft. lbs.) torque.
(2) If the support cushion brackets were removed,
position the brackets onto the lower front sill (Figs. 6
and 8). Install the bolts and stud nuts. Tighten the
bolts to 54 Nzm (40 ft. lbs.) torque and the stud nuts
to 41 Nzm (30 ft. lbs.) torque.
(3) Place the support cushions onto the support
cushion brackets (Fig. 6). Tighten the right support
cushion nuts to 65 Nzm (48 ft. lbs.) torque. Tighten
the left support cushion bolt and nut to 41 Nzm (30
ft. lbs.) torque.
Fig. 4 Oversize and Undersize Component Codes
Fig. 5 Oversize and Undersize Component Code
Location
9 - 14 2.5L ENGINEJ

(4) Install the through bolt and the retaining nut
(Fig. 6). Tighten the through bolt nut to 65 Nzm (48
ft. lbs.) torque.
(5) Remove the engine support.
(6) Lower the vehicle.
(7) Connect negative cable to battery.
REMOVALÐYJ VEHICLES
(1) Disconnect negative cable from battery.
(2) Raise the vehicle.(3) Support the engine.
(4) Remove through bolt nut (Fig. 9). DO NOT re-
move the through bolt.
(5) Remove the retaining bolts and nuts from the
support cushions (Fig. 9).
(6) Remove the through bolt.
(7) Remove the engine support cushions.
Fig. 6 Front MountsÐXJ Vehicles
Fig. 7 Engine Support BracketÐRight Side
Fig. 8 Support Cushion BracketÐLeft Side
Fig. 9 Front MountsÐYJ Vehicles
J2.5L ENGINE 9 - 15

INSTALLATIONÐYJ VEHICLES
(1) If the engine support bracket was removed, po-
sition the bracket onto the block and install the at-
taching bolts (Fig. 9). Tighten the bolts to 62 Nzm (46
ft. lbs.) torque.
(2) Place the support cushion on the support cush-
ion bracket (Fig. 9). Install the support cushion re-
taining bolts and nuts. Tighten the bolts and nuts to
52 Nzm (38 ft. lbs.) torque.
(3) Install the through bolt and the retaining nut
(Fig. 9). Tighten the through bolt nut to 69 Nzm (51
ft. lbs.) torque.
(4) Remove the engine support.
(5) Lower the vehicle.
(6) Connect negative cable to battery.
ENGINE MOUNTÐREAR
A resilient rubber cushion supports the transmis-
sion at the rear between the transmission extension
housing and the rear support crossmember or skid
plate.
REMOVALÐXJ VEHICLES
(1) Disconnect negative cable from battery.
(2) Raise the vehicle and support the transmission.
(3) Remove the nuts holding the support cushion to
the crossmember (Figs. 10 and 11). Remove the cross-
member.
(4)MANUAL TRANSMISSION:
(a) Remove the support cushion nuts and remove
the cushion.
(b) If necessary, remove the bolts holding the
transmission support bracket to the transmission
(Fig. 10). Remove the bracket.
(5)AUTOMATIC TRANSMISSION:
(a) Remove the support cushion bolts and remove
the cushion and the transmission support bracket.(b) If necessary on 2WD vehicles, remove the
bolts holding the transmission support adaptor
bracket to the transmission (Fig. 11). Remove the
adaptor bracket.
INSTALLATIONÐXJ VEHICLES
(1)MANUAL TRANSMISSION:
(a) If removed, position the transmission support
bracket to the transmission and install the bolts.
Tighten the bolts to 43 Nzm (32 ft. lbs.) torque.
(b) Position the support cushion onto the trans-
mission support bracket. Install and tighten the
nuts to 46 Nzm (34 ft. lbs.) torque.
(2)AUTOMATIC TRANSMISSION:
(a) If removed, position the transmission support
adaptor bracket (2WD vehicles) to the transmission
and install the bolts. Tighten the bolts to 75 Nzm
(55 ft. lbs.) torque.
(b) Position the transmission support bracket
and support cushion to the transmission and install
the bolts. Tighten the bolts to 75 Nzm (55 ft. lbs.)
torque.
(3) Position the crossmember onto the support
cushion studs and install the nuts. Tighten the nuts
to 22 Nzm (192 in. lbs.) torque.
(4) Install the crossmember to sill bolts and
tighten to 41 Nzm (30 ft. lbs.) torque.
Fig. 10 Rear MountÐXJ Vehicles (Manual
Transmission)
Fig. 11 Rear MountÐXJ Vehicles (Automatic
Transmission)
9 - 16 2.5L ENGINEJ

(5) Remove the transmission support.
(6) Lower the vehicle.
(7) Connect negative cable to battery.
REMOVALÐYJ VEHICLES
(1) Disconnect negative cable from battery.
(2) Raise the vehicle and support the transmission.
(3) Remove the nuts holding the support cushion to
the skid plate (Figs. 12 and 13).
(4) Remove the skid plate bolts and the skid plate.
(5)MANUAL TRANSMISSION:
(a) Remove the bolts holding the support cushion
and torque arm bracket to the transmission (Fig.
12).
(b) Remove the support cushion and torque arm
bracket.
(6)AUTOMATIC TRANSMISSION:
(a) Remove the bolts and nuts holding the sup-
port cushion to the torque arm bracket (Fig 13).
Remove the support cushion.
(b) Remove the bolts holding the torque arm
bracket to the transmission (Fig. 13). Remove the
torque arm bracket.
INSTALLATIONÐYJ VEHICLES
(1)MANUAL TRANSMISSION:
(a) Position the torque arm bracket and support
cushion to the transmission and install the bolts
(Fig. 12).
(b) Tighten the bolts to 54 Nzm (40 ft. lbs.)
torque.
(2)AUTOMATIC TRANSMISSION:
(a) Position the torque arm bracket to the trans-
mission and install the bolts. Tighten the bolts to
54 Nzm (40 ft. lbs.) torque.
(b) Position the support cushion to the torque
arm bracket and install the bolts and nuts. Tighten
the nuts to 54 Nzm (40 ft. lbs.) torque.(3) Position the skid plate to the studs of the sup-
port cushion and install the nuts (Figs. 12 and 13).
Tighten the stud nuts to 54 Nzm (40 ft. lbs.) torque.
(4) Install the skid plate bolts to the sill and
tighten to 88 Nzm (65 ft. lbs.) torque.
(5) Remove the transmission support.
(6) Lower the vehicle.
(7) Connect negative cable to battery.
ENGINE DAMPER
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove the top and bottom damper nuts (Fig.
14).
(3) Remove the outer retainers and bushings (Fig.
14).
(4) Remove the top damper bracket nut and bolts
(Fig. 14).
(5) Remove the bracket, inner retainers, bushings
and the damper (Fig. 14).
INSTALLATION
(1) Install the damper on the lower bracket with
the lower inner retainer and bushing in place.
Fig. 12 Rear MountÐYJ Vehicles (Manual
Transmission)
Fig. 13 Rear MountÐYJ Vehicles (Automatic
Transmission)
J2.5L ENGINE 9 - 17

(2) Install the upper inner retainer and bushing on
the top of the damper.
(3) Position the upper damper bracket over the
damper and install the stud nut and bolts.
(4) Tighten the stud nut to 23 Nzm (17 ft. lbs.)
torque. Tighten the bracket bolts to 61 Nzm (45 ft.
lbs.) torque.
(5) Install the bushing, upper outer retainer and
damper nut.
(6) Install the bushing, lower outer retainer and
damper nut.
(7) Tighten the upper and lower damper nuts.
(8) Connect negative cable to battery.
ENGINE ASSEMBLYÐXJ VEHICLES
REMOVAL
(1) Disconnect the battery cables. Remove the bat-
tery.
(2) Mark the hinge locations on the hood panel for
alignment reference during installation. Remove the
engine compartment lamp. Remove the hood.
WARNING: THE COOLANT IN A RECENTLY OPER-
ATED ENGINE IS HOT AND PRESSURIZED. USE
CARE TO PREVENT SCALDING BY HOT COOLANT.
CAREFULLY RELEASE THE PRESSURE BEFORE
REMOVING THE RADIATOR DRAIN COCK AND CAP.(3) Remove the radiator drain cock and radiator
cap to drain the coolant. DO NOT waste usable cool-
ant. If the solution is clean, drain the coolant into a
clean container for reuse.
(4) Remove the lower radiator hose.
(5) Remove the upper radiator hose and coolant re-
covery hose (Fig. 15).
(6) Remove the fan shroud (Fig. 15).
(7) Disconnect the transmission fluid cooler tubing
(automatic transmission).
(8) Remove the radiator/condenser (if equipped
with air conditioning).
(9) Remove fan assembly and install a 5/16 x 1/2-
inch SAE capscrew through fan pulley into water
pump flange. This will maintain the pulley and wa-
ter pump in alignment when crankshaft is rotated.
(10) Disconnect the heater hoses (Figs. 16 and 17).
(11) Disconnect the throttle linkages (Fig. 16),
speed control cable (if equipped) and throttle valve
rod.
(12) Disconnect the oxygen sensor wire connector.
(13) Disconnect the wires from the starter motor
solenoid.
(14) Disconnect all fuel injection harness connec-
tions.
(15) Disconnect the quick-connect fuel lines at the
fuel rail and return line by squeezing the two retain-
ing tabs against the fuel tube (Fig. 16). Pull the fuel
tube and retainer from the quick-connect fitting (re-
fer to Group 14, Fuel System for the proper proce-
dure).
(16) Remove the fuel line bracket from the intake
manifold.
(17) Remove the air cleaner assembly (Fig. 18).
(18) If equipped with air conditioning, remove the
service valves and cap the compressor ports.
(19) Remove the power brake vacuum check valve
from the booster, if equipped.
(20) If equipped with power steering (Fig. 18):
Fig. 14 Engine Damper
Fig. 15 Upper Radiator Hose, Coolant Recovery
Hose & Fan Shroud
9 - 18 2.5L ENGINEJ