2.5 engine JEEP YJ 1995 Service And Owners Manual

FOR EXAMPLE:DO NOT use a standard size up-
per insert and a 0.051 mm (0.002 inch) undersize
lower insert.
If the clearance exceeds specification using a pair
of 0.051 mm (0.002 inch) undersize bearing inserts,
measure crankshaft journal diameter with a mi-
crometer. If the journal diameter is correct, the
crankshaft bore in the cylinder block may be mis-
aligned, which requires cylinder block replacement or
machining to true bore.
If journals 1 through 5 diameters are less than
63.4517 mm (2.4981 inches), replace crankshaft or
grind crankshaft down to accept the appropriate un-
dersize bearing inserts.
Once the proper clearances have been obtained,
proceed to Crankshaft Main BearingÐInstallation.
MAIN BEARING JOURNAL DIAMETER (CRANKSHAFT
REMOVED)
Remove the crankshaft from the cylinder block (re-
fer to Cylinder Block - Disassemble).
Clean the oil off the main bearing journal.
Determine the maximum diameter of the journal
with a micrometer. Measure at two locations 90É
apart at each end of the journal.
The maximum allowable taper and out of round is
0.013 mm (0.0005 inch). Compare the measured di-
ameter with the journal diameter specification (Main
Bearing Fitting Chart). Select inserts required to ob-
tain the specified bearing-to-journal clearance.
Once the proper clearances have been obtained,
proceed to Crankshaft Main BearingÐInstallation.
INSTALLATION
(1) Lubricate the bearing surface of each insert
with engine oil.
(2) Loosen all the main bearing caps. Install the
main bearing upper inserts.
(3) Install the lower bearing inserts into the main
bearing caps.
(4) Install the main bearing cap(s) and lower in-
sert(s).
(5) Clean the rear main bearing cap (No.5) mating
surfaces.
(6) Apply Loctite 518, or equivalent on the rear
bearing cap (Fig. 6). The bead should be 3 mm (0.125
in) thick. DO NOT apply Loctite 518, or equivalent to
the lip of the seal.
(7) Install the rear main bearing cap. DO NOT
strike the cap more than twice for proper engage-
ment.
(8) Tighten the bolts of caps 1, 3, 4 and 5 to 54
Nzm (40 ft. lbs.) torque. Now tighten these bolts to 95
Nzm (70 ft. lbs.) torque. Finally, tighten these bolts to
108 Nzm (80 ft. lbs.) torque.
(9) Push the crankshaft forward and backward.
Load the crankshaft front or rear and tighten cap
bolt No.2 to 54 Nzm (40 ft. lbs.) torque. Then tightento 95 Nzm (70 ft. lbs.) torque and finally tighten to
108 Nzm (80 ft. lbs.) torque.
(10) Rotate the crankshaft after tightening each
main bearing cap to ensure the crankshaft rotates
freely.
(11) Check crankshaft end play. Crankshaft end
play is controlled by the thrust bearing which is
flange and installed at the No.2 main bearing posi-
tion.
(a) Attach a magnetic base dial indicator to the
cylinder block at either the front or rear of the en-
gine.
(b) Position the dial indicator rod so that it is
parallel to the center line of the crankshaft.
(c) Pry the crankshaft forward, position the dial
indicator to zero.
(d) Pry the crankshaft forward and backward.
Note the dial indicator readings. End play is the
difference between the high and low measurements
(Fig. 7). Correct end play is 0.038-0.165 mm
(0.0015-0.0065 inch). The desired specifications are
0.051-0.064 mm (0.002-0.0025 inch).
(e) If end play is not within specification, inspect
crankshaft thrust faces for wear. If no wear is ap-
parent, replace the thrust bearing and measure
end play. If end play is still not within specifica-
tion, replace the crankshaft.
If the crankshaft was removed, install the crank-
shaft into the cylinder block (refer to Cylinder Block -
Assemble).
(12) Install the oil pan.
Fig. 6 Location of Loctite 518 (or equivalent)
J2.5L ENGINE 9 - 47

MAIN BEARING FITTING CHART
9 - 48 2.5L ENGINEJ

(13) Install the drain plug. Tighten the plug to 34
Nzm (25 ft. lbs.) torque.
(14) Lower the vehicle.
(15) Install the spark plugs. Tighten the plugs to
37 Nzm (27 ft. lbs.) torque.
(16) Fill the oil pan with engine oil to the full
mark on the dipstick level.
(17) Connect negative cable to battery.
REAR MAIN OIL SEALS
REMOVAL
(1) Remove the flywheel or converter drive plate.
Discard the old bolts.
(2) Pry out the seal from around the crankshaft
flange (Fig. 8).
INSTALLATION
(1) Coat the outer lip of the replacement rear main
bearing seal with engine oil.(2) Carefully position the seal into place. Use rear
main Seal Installer Tool 6271 to install the seal flush
with the cylinder block.
CAUTION: The felt lip must be located inside the
flywheel mounting surface. If the lip is not posi-
tioned correctly the flywheel could tear the seal.
(3) Install the flywheel or converter drive plate.
New bolts MUST be used when installing the fly-
wheel or converter plate. Tighten the new bolts to 68
Nzm (50 ft. lbs.) torque. Turn the bolts an additional
60É.
CYLINDER BLOCK
Remove the Engine Assembly from the vehicle.
DISASSEMBLY
Refer to the applicable sections for detailed instruc-
tions.
(1) Drain the engine oil. Remove and discard the
oil filter.
(2) Remove the water pump from the cylinder
block.
(3) Remove the distributor from the cylinder block.
(4) Remove the vibration damper.
(5) Remove the timing case cover and lay the cover
upside down.
(6) Position a drift punch into the slot in the back
of the cover and tap the old seal out.
(7) Remove the timing chain bumper.
(8) Remove the oil slinger from crankshaft.
(9) Remove the camshaft retaining bolt and re-
move the sprockets and chain as an assembly.
(10) Remove the camshaft.
(11) Remove the oil pan and gasket.
(12) Remove the timing chain tensioner.
(13) Remove the front and rear oil galley plugs.
(14) Remove the connecting rods and the pistons.
Remove the connecting rod and piston assemblies
through the top of the cylinder bores.
(15) Remove the crankshaft.
CLEANING
Thoroughly clean the oil pan and engine block gas-
ket surfaces.
Use compressed air to clean out:
²The galley at the oil filter adaptor hole, the filter
bypass hole (Fig. 9).
²The front and rear oil galley holes (Figs. 10 and
11).
²The feed holes for the crankshaft main bearings.
Once the block has been completely cleaned, apply
Loctite PST pipe sealant with Teflon 592 to the
threads of the front and rear oil galley plugs. Tighten
the plugs to 41 Nzm (30 ft. lbs.) torque.
Fig. 7 Crankshaft End Play Measurement
Fig. 8 Replacement of Rear Crankshaft Oil Seal
J2.5L ENGINE 9 - 49

INSPECTIONÐCYLINDER BORE
(1) It is mandatory to use a dial bore gauge to
measure each cylinder bore diameter (Fig. 12). To
correctly select the proper size piston, a cylinder bore
gauge, Special Tool 6879, capable of reading in .00019INCREMENTS is required. If a bore gauge is not
available, do not use an inside micrometer.
(2) Measure the inside diameter of the cylinder
bore at three levels below top of bore. Start perpen-
dicular (across or at 90 degrees) to the axis of the
crankshaft and then take two additional readings.
(3) Measure the cylinder bore diameter crosswise
to the cylinder block near the top of the bore. Repeat
the measurement near the middle of the bore, then
repeat the measurement near the bottom of the bore.
(4) Determine taper by subtracting the smaller di-
ameter from the larger diameter.
(5) Rotate measuring device 90É and repeat steps
above.
(6) Determine out-of-roundness by comparing the
difference between each measurement.
(7) If cylinder bore taper does not exceed 0.025 mm
(0.001 inch) and out-of-roundness does not exceed
0.025 mm (0.001 inch), the cylinder bore can be
honed. If the cylinder bore taper or out-of-round con-
dition exceeds these maximum limits, the cylinder
must be bored and then honed to accept an oversize
piston. A slight amount of taper always exists in the
cylinder bore after the engine has been in use for a
period of time.
HONINGÐCYLINDER BORE
The honing operation should be closely coordinated
with the fitting of pistons and rings. This will ensure
specified clearances are maintained.
Refer to Standard Service Procedures in the begin-
ning of this Group for the proper honing of cylinder
bores.
Fig. 9 Oil Filter Adaptor Hole
Fig. 10 Front Oil Galley Hole
Fig. 11 Rear Oil Galley Hole
Fig. 12 Cylinder Bore Measurement
9 - 50 2.5L ENGINEJ

ASSEMBLY
Refer to the applicable sections for detailed instruc-
tions.
(1) Install the crankshaft.
(2) Install the connecting rods and the pistons
through the top of the cylinder bores.
(3) Install the front and rear oil galley plugs.
(4) Install the timing chain tensioner.
(5) Install the camshaft.
(6) Install the sprockets and chain as an assembly.
(7) Install the oil slinger to the crankshaft.
(8) Install the timing chain bumper.
(9) Install the timing case cover seal.
(10) Install the timing case cover.(11) Install the oil pan gasket and oil pan.
(12) Install the vibration damper.
(13) Install the water pump. Tighten the mounting
bolts to 31 Nzm (270 in. lbs.) torque.
(14) Remove the distributor from the cylinder
block.
(15) Lubricate the oil filter seal with clean engine
oil. Tighten oil filter to 18 Nzm (13 ft. lbs.) torque.
(16) Install the engine into the vehicle.
(17) Fill the engine with clean lubrication oil (refer
to Group 0, Lubrication and Maintenance).
(18) Fill the cooling system (refer to Group 7, Cool-
ing System for the proper procedures).
J2.5L ENGINE 9 - 51

SPECIFICATIONS
ENGINE SPECIFICATIONS
9 - 52 2.5L ENGINEJ

ENGINE SPECIFICATIONS (CONT.)
J2.5L ENGINE 9 - 53

ENGINE SPECIFICATIONS (CONT.)
TORQUE SPECIFICATIONS
9 - 54 2.5L ENGINEJ

SERVICE PROCEDURES
INDEX
page page
Catalytic Converter......................... 4
Engine Exhaust ManifoldÐ2.5L Engine.......... 7
Engine Exhaust ManifoldÐ4.0L Engine.......... 7
Exhaust PipeÐXJ Vehicles................... 3
Exhaust PipeÐYJ Vehicles................... 4Intake ManifoldÐ2.5L Engine................. 7
Intake ManifoldÐ4.0L Engine................. 8
Muffler and Exhaust TailpipeÐXJ Vehicles........ 5
Muffler and Exhaust TailpipeÐYJ Vehicles........ 6
EXHAUST PIPEÐXJ VEHICLES
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
REMOVAL
(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with heat valve lu-
bricant (Fig. 1). Allow 5 minutes for penetration.
(3) Remove the oxygen sensor from the exhaust
pipe (Fig. 2).
(4) Disconnect the exhaust pipe from the engine
exhaust manifold. Discard the seal (4.0L engine,
only).(5) Support the transmission and remove the rear
crossmember.
(6) Remove the clamp nuts and clamp (Fig. 3). To
remove the exhaust pipe from the catalytic converter,
apply heat until the metal becomes cherry red. Dis-
connect the exhaust pipe from the catalytic converter
(Fig. 3). Remove the exhaust pipe.
Fig. 1 Exhaust Pipe-to-Engine Exhaust Manifold
Nuts
Fig. 2 Oxygen Sensor
Fig. 3 Exhaust Pipe-to-Catalytic Converter
Connection
JEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 3

INSTALLATION
(1) Install the muffler onto the catalytic converter
outlet. Ensure that the locator on the converter
aligns with the notch on the muffler, if so equipped.
Install the clamp and tighten the nuts finger tight.
(2) Install the exhaust tailpipe into the muffler
outlet. Ensure that the locator on the exhaust
tailpipe aligns with the notch on the muffler, if so
equipped. Install the clamp and tighten the nuts fin-
ger tight.
(3) Install the front exhaust tailpipe supports and
the rear exhaust tailpipe hanger. Ensure that the ex-
haust tailpipe has sufficient clearance from the floor
pan and shields.
(4) Tighten the nuts on the muffler-to-catalytic
converter and the muffler-to-exhaust tailpipe clamps
to 61 Nzm (45 ft. lbs.) torque.
(5) Lower the vehicle.
(6) Start the engine and inspect for exhaust leaks
and contact with the body panels and shields.
ENGINE EXHAUST MANIFOLDÐ2.5L ENGINE
REMOVAL
(1) Disconnect the battery negative cable.
(2) Remove all components attached to the intake
manifold.
(3) Raise the vehicle.
(4) Disconnect the exhaust pipe from the engine
exhaust manifold.
(5) Lower the vehicle.
(6) Remove fasteners 2 through 5 and remove the
intake manifold (Fig. 11).
(7) Remove fasteners 1, 6 and 7 and remove the
engine exhaust manifold (Fig. 11).
CLEANING
Clean the intake and engine exhaust manifolds and
cylinder head mating surfaces.DO NOT allow for-eign material to enter either the intake mani-
fold or the ports in the cylinder head.
INSTALLATION
(1) Install a new intake manifold gasket over the
alignment dowels on the cylinder head.
(2) Install the engine exhaust manifold assembly.
Exhaust manifold must be centrally located
over the end studs and spacer (Fig. 11).
(3) Tighten bolt No.1 to 41 Nzm (30 ft. lbs.) torque
(Fig. 11).
(4) Install the intake manifold on the cylinder
head dowels (Fig. 11).
(5) Install bolts 2 through 5 (Fig. 11). Tighten
these bolts to 31 Nzm (23 ft. lbs.) torque.
(6) Install new engine exhaust manifold spacers
over the engine exhaust manifold mounting studs in
the cylinder head (Fig. 11).
(7) Tighten nuts 6 and 7 to 31 Nzm (23 ft. lbs.)
torque (Fig. 11).
(8) Install all components to the intake manifold.
(9) Raise the vehicle.
(10) Connect the exhaust pipe to the engine ex-
haust manifold. Tighten the bolts to 31 Nzm (23 ft.
lbs.) torque.
(11) Lower the vehicle.
(12) Connect the battery negative cable.
(13) Start the engine and check for leaks.
ENGINE EXHAUST MANIFOLDÐ4.0L ENGINE
The intake and engine exhaust manifolds on the
4.0L engine must be removed and installed together.
The manifolds use a common gasket at the cylinder
head.
Refer to Intake ManifoldÐ4.0L Engine in this sec-
tion for the proper removal and installation proce-
dures.
INTAKE MANIFOLDÐ2.5L ENGINE
REMOVAL
(1) Disconnect the battery negative cable.
(2) Remove the air inlet hose from the throttle
body and air cleaner.
(3) Loosen the accessory drive belt tension and re-
move the belt from the power steering pump.
(4) Remove the power steering pump and brackets
from the water pump and intake manifold. Support
power steering pump and bracket with mechanics
wire attached to the radiator upper crossmember.
(5) Remove the fuel tank filler cap to relieve the
fuel tank pressure.
(6) Install the fuel tank filler cap.
(7) Disconnect fuel supply and return tube from
the fuel rail (refer to Group 14, Fuel System - Quick
Connect Fittings).
(8) Disconnect the accelerator cable from the throt-
tle body and the holddown bracket.
Fig. 11 Intake/Engine Exhaust Manifold Installation
(2.5L Engine)
JEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 7