1991 1999 ford explorer chilton User Manual

							Click to enlarge
If equipped, install the oil baffle.
5. 
Install rocker arm shaft assembly to the cylinder head and guide adjusting screws on to the pushrods.
6. 
Install and tighten rocker arm stand attaching bolts to specification, two turns at a time, in sequence
(from middle of shaft to the end of shaft).
7. 
Adjust the valve lash to the cold specified setting. Refer to Section 1 under Valve Lash Adjustment
for procedures.
8. 
Install the valve rocker arm covers.
9. 
DISASSEMBLY & REASSEMBLY Remove the spring washer and pin from each end of the valve rocker arm shaft.
1. 
Slide the rocker arms, springs and rocker arm shaft supports off the shaft. Be sure to mark the parts
for re-assembly in the same locations.
2. 
If it is necessary to remove the plugs from each end of the shaft, drill or pierce the plug on one end.
Use a steel rod to knock out the plug on the opposite end. Working from the open end, knock out the
remaining plug.
3. 
The oil holes in the rocker arm shaft must point down when the shaft is installed. This position of the
shaft can be recognized by a notch on the front face of the shaft.
4. 
If the plugs were removed from the shaft, use a blunt tool and install a plug, cup side out, in each end
of the shaft.
5. 
Install a spring washer and pin on one end of the shaft, coat the rocker arm shaft with heavy engine oil
and install the parts in the same sequence they were removed.
6. 
Thermostat
REMOVAL & INSTALLATION
2.3L and 2.5L Engines Drain the cooling system below the level of the coolant outlet housing.
1. 
CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are
quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove
fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless
it is contaminated or several years old.
Exploded view of the thermostat assembly for 2.3L and 2.5L enginesHOW TO USE THIS BOOK
274 DISASSEMBLY & REASSEMBLY 
						

							Disconnect the heater return hose at the thermostat housing located on the left front lower side of
engine.
2. 
Remove the coolant outlet housing retaining bolts and slide the housing with the hose attached to one
side.
3. 
Remove the thermostat from the outlet.
4. 
Remove the gasket from the engine block and clean both mating surfaces.
5. 
It is good practice to check the operation of a new thermostat before it is installed in an engine. Place
the thermostat in a pan of boiling water. If it does not open more than  1
/4  in., do not install it in the
engine.
To install: Coat a new gasket with water resistant sealer and position it on the outlet of the engine. The gasket
must be in place before the thermostat is installed.
6. 
Install the thermostat with the bridge (opposite end from the spring) inside the elbow connection and
turn it clockwise to lock it in position, with the bridge against the flats cast into the elbow connection.
7. 
Position the elbow connection onto the mounting surface of the outlet, so that the thermostat flange is
resting on the gasket and install the retaining bolts.
8. 
Connect the heater hose to the thermostat housing.
9. 
Fill the radiator and operate the engine until it reaches operating temperature. Check the coolant level
and adjust as necessary.
10. 
3.0L Engine Drain the cooling system.
1. 
CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are
quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove
fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless
it is contaminated or several years old.
Disconnect the battery ground cable.
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REMOVAL & INSTALLATION 275 
						

							Thermostat installation for the 3.0L engine
Click to enlarge
Remove the upper radiator hose.
3. 
Remove the thermostat housing bolts.
4. 
Remove the housing and thermostat as an assembly.
5. 
Remove the thermostat from the housing.
6. 
To install: Clean all gasket material from the housing and engine.
7. 
Turn the thermostat clockwise into the housing until the thermostat bridge is perpendicular to the
mounting holes.
8. 
Position the housing on the engine, using a new gasket coated with sealer. Tighten the bolts to 5 ft.
lbs. (26 Nm).
9. 
Install the hose, fill and bleed the cooling system, connect the battery ground cable and start the
engine. Check for leaks.
10. 
2.9L and 4.0L Engines Drain the cooling system.
1. 
CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are
quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove
fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless
it is contaminated or several years old.
Disconnect the battery ground.
2. 
Remove the air cleaner duct assembly.
3. 
Remove the upper radiator hose.
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276 REMOVAL & INSTALLATION 
						

							Exploded view of the thermostat housing for the 4.0L engine-2.9L engine is similar
Click to enlarge
To remove the thermostat, first remove the upper radiator hose, then the three attaching screws HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 277 
						

							Pull the thermostat housing from the intake manifold ...
... then remove the thermostat
Ensure that the sealing ring is properly seated. Install the thermostat with the release valve facing upwards
Remove the 3 thermostat housing attaching bolts.
5. 
Remove the thermostat housing. You may have to tap it loose with a plastic mallet or your hand.
6. 
Pull the thermostat from the intake manifold.
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278 REMOVAL & INSTALLATION 
						

							
To install:
WARNING
Do not use a sharp metal tool for scraping. Damage to the sealing surfaces could result and cause a leak.
Clean all mating surfaces thoroughly.
8. 
Make sure that the sealing ring is properly installed on the thermostat rim. Position the thermostat in
the housing making sure that the air release valve is in the up(12 oclock) position.
9. 
Coat the mating surfaces of the housing and engine with an adhesive type sealer. Position the new
gasket on the thermostat and place the housing on the engine. Tighten the bolts to specification.
10. 
5.0L Engine Drain the cooling system.
1. 
CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are
quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove
fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless
it is contaminated or several years old.
Disconnect the battery ground.
2. 
Remove the upper radiator hose.
3. 
Exploded view of the 5.0L engine thermostat and related components Click to enlarge
Remove the 2 thermostat housing attaching bolts.
4. 
Loosen the bypass hose at the water pump.
5. 
Remove the thermostat housing. You may have to tap it loose with a plastic mallet or your hand.
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REMOVAL & INSTALLATION 279 
						

							
To install:
WARNING
Do not use a sharp metal tool for scraping. Damage to the sealing surfaces could result and cause a leak.
Align the air bleed hole on the thermostat with the notch in the housing, which is also the 12 oclock position
Clean all mating surfaces thoroughly.
7. 
Position the thermostat in the housing making sure that the air release valve is in the up(12 oclock)
position.
8. 
Coat the mating surfaces of the housing and engine with an adhesive type sealer. Position the new
gasket on the engine and place the housing on the engine. Tighten the bolts to specifications.
9. 
Intake Manifold
The engines covered by this manual utilize an upper and lower intake manifold assembly. If necessary, only
the upper intake manifold may be removed by following the intake manifold procedure up to that point.
Obviously, installation would also begin at the upper intake steps.
REMOVAL & INSTALLATION WARNING
Anytime the upper or lower intake manifold has been removed, cover all openings with a rag or a sheet of
plastic to prevent dirt and debris from falling into the engine.
2.3L and 2.5L Engines HOW TO USE THIS BOOK
280 Intake Manifold 
						

							Exploded view of the upper and lower intake manifold assemblies on the 2.3L and 2.5L engine
Click to enlarge
The intake manifold is a two-piece (upper and lower) aluminum casting. Runner lengths are tuned to optimize
engine torque and power output. The manifold provides mounting flanges for the air throttle body assembly,
fuel supply manifold, accelerator control bracket and the EGR valve and supply tube. A vacuum fitting is
installed to provide vacuum to various engine accessories. Pockets for the fuel injectors are machined to
prevent both air and fuel leakage. The following procedure is for the removal of the intake manifold with the
fuel charging assembly attached.
Make sure the ignition is off, then drain the coolant from the radiator (engine cold).
1. 
CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are
quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove
fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless
it is contaminated or several years old. HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 281 
						

							Disconnect the negative battery cable and secure it out of the way.
2. 
Remove the fuel filler cap to vent tank pressure. Release the pressure from the fuel system at the fuel
pressure relief valve using EFI pressure gauge T80L-9974-A or equivalent. The fuel pressure relief
valve is located on the fuel line in the upper right hand corner of the engine compartment. Remove the
valve cap to gain access to the valve.
3. 
Label and unplug any electrical connectors related to the intake manifold assemblies being removed.
4. 
Linkage and hose location on the 2.3L and 2.5L engineClick to enlarge
Disconnect the EGR valve supply tube Click to enlarge
Tag and disconnect the vacuum lines at the upper intake manifold vacuum tree, at the EGR valve and
at the fuel pressure regulator and canister purge line as necessary.
5. 
Remove the throttle linkage shield and disconnect the throttle linkage and speed control cable (if
equipped). Unbolt the accelerator cable from the bracket and position the cable out of the way.
6. 
Disconnect the air intake hose, air bypass hose and crankcase vent hose.
7. 
Disconnect the PCV hose from the fitting on the underside of the upper intake manifold.
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282 REMOVAL & INSTALLATION 
						

							Loosen the clamp on the coolant bypass line at the lower intake manifold and disconnect the hose.
9. 
Disconnect the EGR tube from the EGR valve by removing the flange nut.
10. 
Upper intake manifold removal on the 2.3L and 2.5L engine Click to enlarge
Remove the upper intake manifold retaining nuts. Remove the upper intake manifold and throttle
body assembly.
11. 
If you only need to remove the upper intake manifold, stop at this point. Otherwise, continue with the
procedure to also remove the lower intake manifold. HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 283