Page 369 of 2889

INSTALLATION
CAUTION: When installing the accessory drive belt,
the belt must be routed correctly. If not, engine may
overheat due to water pump rotating in wrong
direction. Refer to (Fig. 21) (Fig. 22) for correct
engine belt routing. The correct belt with correct
length must be used.
(1) Position drive belt over all pulleysexcept
water pump pulley.
(2) Attach a 3/8 inch ratchet to tensioner.
(3) Rotate ratchet and belt tensioner counterclock-
wise. Place belt over water pump pulley. Let ten-
sioner rotate back into place. Remove ratchet. Be
sure belt is properly seated on all pulleys.
VACUUM PUMP - 5.9L DIESEL
DESCRIPTION
The vacuum pump and the power steering pump
are combined into a single assembly on diesel engine
models (Fig. 23). Both pumps are operated by a drive
gear attached to the vacuum pump shaft. The shaft
gear is driven by the camshaft gear.
The vacuum pump is a constant displacement,
vane-type pump. Vacuum is generated by four vanes
mounted in the pump rotor. The rotor is located in
the pump housing and is pressed onto the pump
shaft.
The vacuum and steering pumps are operated by a
single drive gear pressed onto the vacuum pump
shaft. The drive gear is operated by the engine cam-
shaft gear.
The vacuum and power steering pump shafts are
connected by a coupling. Each pump shaft has an
adapter with drive lugs that engage in the coupling.
The vacuum pump rotating components are lubri-
cated by engine oil. Lubricating oil is supplied to the
pump through an oil line at the underside of the
pump housing.
Fig. 21 Belt RoutingÐ5.9L Diesel EngineÐWith A/C
1 - GENERATOR PULLEY
2 - WATER PUMP PULLEY
3 - FAN PULLEY
4 - CRANKSHAFT PULLEY
5 - AUTOMATIC TENSIONER
6 - A/C COMPRESSOR PUMP PULLEY
Fig. 22 Belt RoutingÐ5.9L Diesel EngineÐWithout
A/C
1 - GENERATOR PULLEY
2 - FAN PULLEY
3 - CRANKSHAFT PULLEY
4 - AUTOMATIC TENSIONER
5 - WATER PUMP PULLEY
7 - 34 ACCESSORY DRIVEBR/BE
DRIVE BELTS - 5.9L DIESEL (Continued)
Page 370 of 2889

The complete assembly must be removed in order
to service either pump. However, the power steering
pump can be removed and serviced separately when
necessary.
The vacuum pump is not a serviceable component.
If diagnosis indicates a pump malfunction, the pump
must be replaced as an assembly. Do not disassemble
or attempt to repair the pump.
The combined vacuum and steering pump assem-
bly must be removed for access to either pump. How-
ever, the vacuum pump can be removed without
having to disassemble the power steering pump.
If the power steering pump requires service, simply
remove the assembly and separate the two pumps.
Refer to the pump removal and installation proce-
dures in this section.
OPERATION
Vacuum pump output is transmitted to the
HEVAC, speed control, systems through a supply
hose. The hose is connected to an outlet port on the
pump housing and uses an in-line check valve to
retain system vacuum when vehicle is not running.
Pump output ranges from a minimum of 8.5 to 25
inches vacuum.
The pump rotor and vanes are rotated by the pump
drive gear. The drive gear is operated by the cam-
shaft gear.
DIAGNOSIS AND TESTINGÐVACUUM PUMP
OUTPUT
The vacuum pump supplies necessary vacuum to
components in the following systems:
²HEVAC system
²Speed Control System
A quick check to determine if the vacuum pump is
the cause of the problem in any of these systems is to
road test the vehicle and verify that all of these sys-
tems are fuctioning properly. If only one of these has
a vacuum related failure, then it is likely the vacuum
pump is not the cause.
A standard vacuum gauge can be used to check
pump output when necessary. Simply disconnect the
pump supply hose and connect a vacuum gauge to
the outlet port for testing purposes. With the engine
running, vacuum output should be a minimum of 25
inches, depending on engine speed.
DIAGNOSING LOW VACUUM OUTPUT CONDITION
If the vacuum pump is suspected of low vacuum
output, check the pump and vacuum harnesses as
follows:
(1) Visually inspect the vacuum harness for obvi-
ous failures (i.e. disconnected, cracks, breaks etc.)
(2) Disconnect the vacuum supply hose at the vac-
uum pump check valve. Connect vacuum gauge to
this valve and run engine at various throttle open-
ings. Output should be a minimum 25 inches of vac-
uum. If vacuum is consistently below 25 inches, the
vacuum pump should be replaced. If output is within
specified limits, the vacuum harness should be sus-
pected as the cause.
(3) Disconnect and isolate the vacuum supply har-
ness. Cap off open ends and apply roughly 15 inches
of vacuum to the harness. If the vacuum gauge does
not hold its reading, then there is an open in the har-
ness and it should be repaired or replaced.
(4) If the vacuum loss is still not detected at this
point, then the pump and harness are not the cause
of the low vacuum condition. Apply vacuum to the
related components of the vacuum supply system (i.e.
valves, servos, solenoids, etc.) to find the source of
the vacuum loss.
REMOVAL
(1) Disconnect battery negative cables.
(2) Position drain pan under power steering pump.
(3) Disconnect vacuum and steering pump hoses.
(4) Disconnect lubricating oil feed line from fitting
at underside of vacuum pump (Fig. 24).
(5) Remove lower bolt that attaches pump assem-
bly to engine block (Fig. 25).
Fig. 23 Diesel Vacuum & Power Steering Pump
Assembly
1 - VACUUM PUMP
2 - POWER STEERING PUMP
3 - PUMP ADAPTER
4 - DRIVE GEAR
BR/BEACCESSORY DRIVE 7 - 35
VACUUM PUMP - 5.9L DIESEL (Continued)
Page 371 of 2889

(6) Remove bottom, inboard nut that attaches
adapter to steering pump. This nut secures a small
bracket to engine block. Nut and bracket must be
removed before pump assembly can be removed from
block.
(7) Remove upper bolt that attaches pump assem-
bly to engine block (Fig. 26).
(8) Remove pump assembly from vehicle.
NOTE: The vacuum pump and adapter are serviced
as an assembly and must not be seperated.
(9) Remove the remaining three power steering
pump to adapter mounting nuts (Fig. 27).
(10) Gently, remove the steering pump from the
adapter. Use caution not to damage the oil seal in
the adapter body (Fig. 28).
Fig. 24 Vacuum Pump Oil Feed Line
1 - ENGINE BLOCK
2 - VACUUM PUMP
3 - VACUUM PUMP OIL FEED LINE
Fig. 25 Vacuum Pump Mounting
1 - PUMP ASSEMBLY LOWER MOUNTING BOLT
2 - ADAPTER BRACKET
3 - BOTTOMÐINBOARD ADAPTER BRACKET NUT
Fig. 26 Pump Assembly Upper Mounting Bolt
1 - PUMP UPPER BOLT
2 - DRIVE COVER
7 - 36 ACCESSORY DRIVEBR/BE
VACUUM PUMP - 5.9L DIESEL (Continued)
Page 372 of 2889

INSTALLATION
NOTE: Make sure the two pump spacers are
present before assembling power steering pump to
adapter.
(1) Aline the steering pump drive dog with the slot
in the vacuum pump drive assembly, slide the steer-
ing pump into place on the adapter.Use care not to
damage the oil seal in the adapter body.
(2) Install the three steering pump to adapter
nuts, do not install the lower inboard mounting nut
at this time. Tighten nuts to 24 N´m (18 ft. lbs.).
(3) Position new gasket on vacuum pump mount-
ing flange (Fig. 29). Use MopartPerfect Seal, or sil-
icone adhesive/sealer to hold gasket in place.
(4) Insert pump assembly upper attaching bolt in
mounting flange and gasket. Use sealer or grease to
hold bolt in place if necessary.
(5) Position pump assembly on engine and install
upper bolt (Fig. 30). Tighten upper bolt only enough
to hold assembly in place at this time.
Fig. 27 Adapter to Power Steering Pump Nuts
1 - VACUUM PUMP
2 - ATTACHING NUTS
3 - STEERING PUMP
4 - PUMP SPACERS
5 - OIL FEED FITTING
Fig. 28 Steering Pump, Vacuum Pump and Adapter
1 - PUMP SHAFT
2 - VACUUM FITTING
3 - VACUUM PUMP DRIVE
4 - OIL SEAL
5 - MOUNTING BRACKET
6 - DRIVE DOG
7 - PUMP SPACERS
Fig. 29 Pump Mounting Flange Gasket
1 - PUMP MOUNTING FLANGE
2 - PUMP GASKET (APPLY SEALER TO BOTH SIDES)
BR/BEACCESSORY DRIVE 7 - 37
VACUUM PUMP - 5.9L DIESEL (Continued)
Page 373 of 2889
(6) Working from under vehicle, install pump
assembly lower attaching bolt. Then tighten upper
and lower bolt to 77 N´m (57 ft. lbs.).
(7) Position bracket on steering pump inboard
stud. Then install remaining adapter attaching nut
on stud. Tighten nut to 24 N´m (18 ft. lbs.).
(8) Connect oil feed line to vacuum pump connec-
tor and tighten line fitting.
(9) Connect steering pump pressure and return
lines to pump. Tighten pressure line fitting to 30
N´m (22 ft. lbs.).
(10) Connect vacuum hose to vacuum pump.
(11) Connect battery cables, if removed.
(12) Fill power steering pump reservoir and Purge
air from steering pump lines (Refer to 19 - STEER-
ING/PUMP - STANDARD PROCEDURE).
Fig. 30 Installing Pump Assembly On Engine
1 - PUMP ASSEMBLY
2 - PUMP GASKET
3 - DRIVE GEAR
7 - 38 ACCESSORY DRIVEBR/BE
VACUUM PUMP - 5.9L DIESEL (Continued)
Page 374 of 2889

ENGINE
TABLE OF CONTENTS
page page
COOLANT
DESCRIPTION...........................40
OPERATION.............................40
COOLANT RECOVERY CONTAINER - 3.9L/5.2L/
5.9L/5.9L DIESEL
DESCRIPTION...........................41
OPERATION.............................41
REMOVAL..............................41
INSTALLATION...........................41
COOLANT RECOVERY CONTAINER - 8.0L
DESCRIPTION...........................42
OPERATION.............................42
RADIATOR FAN - 3.9L/5.2L/5.9L/8.0L
REMOVAL..............................42
CLEANING..............................43
INSPECTION............................43
INSTALLATION...........................43
RADIATOR FAN - 5.9L DIESEL
REMOVAL..............................44
CLEANING..............................44
INSPECTION............................44
INSTALLATION...........................45
ENGINE BLOCK HEATER - 3.9L/5.2L/5.9L
DESCRIPTION...........................45
OPERATION.............................45
REMOVAL..............................45
INSTALLATION...........................45
ENGINE BLOCK HEATER - 8.0L
DESCRIPTION...........................46
OPERATION.............................46
REMOVAL..............................46
INSTALLATION...........................46
ENGINE BLOCK HEATER - 5.9L DIESEL
DESCRIPTION...........................47
OPERATION.............................47
REMOVAL..............................47
INSTALLATION...........................47
ENGINE COOLANT TEMP SENSOR - 3.9L/5.2L/
5.9L
DESCRIPTION...........................48
OPERATION.............................48
REMOVAL..............................48
INSTALLATION...........................48
ENGINE COOLANT THERMOSTAT - 3.9L/5.2L/
5.9L
DESCRIPTION...........................49
OPERATION.............................49
DIAGNOSIS AND TESTING.................49
THERMOSTAT.........................49REMOVAL..............................49
INSTALLATION...........................50
ENGINE COOLANT THERMOSTAT - 8.0L
DESCRIPTION...........................52
OPERATION.............................52
DIAGNOSIS AND TESTING.................52
THERMOSTAT.........................52
REMOVAL..............................52
INSTALLATION...........................53
ENGINE COOLANT THERMOSTAT - 5.9L
DIESEL
DESCRIPTION...........................54
OPERATION.............................54
DIAGNOSIS AND TESTING.................54
THERMOSTAT.........................54
REMOVAL..............................55
INSTALLATION...........................55
FAN DRIVE VISCOUS CLUTCH - 3.9L/5.2L/5.9L/
8.0L
DESCRIPTION...........................56
OPERATION.............................56
DIAGNOSIS AND TESTING.................56
VISCOUS FAN DRIVE...................56
FAN DRIVE VISCOUS CLUTCH - 5.9L DIESEL
DESCRIPTION...........................57
OPERATION.............................57
DIAGNOSIS AND TESTING.................58
VISCOUS FAN DRIVE...................58
RADIATOR - 3.9L/5.2L/5.9L
DESCRIPTION...........................59
OPERATION.............................59
DIAGNOSIS AND TESTING.................59
RADIATOR COOLANT FLOW..............59
REMOVAL..............................59
CLEANING..............................60
INSPECTION............................61
INSTALLATION...........................61
RADIATOR - 8.0L
DESCRIPTION...........................61
OPERATION.............................61
DIAGNOSIS AND TESTING.................61
RADIATOR COOLANT FLOW..............61
REMOVAL..............................62
CLEANING..............................62
INSPECTION............................62
INSTALLATION...........................63
RADIATOR - 5.9L DIESEL
DESCRIPTION...........................63
OPERATION.............................63
BR/BEENGINE 7 - 39
Page 375 of 2889

DIAGNOSIS AND TESTING.................63
RADIATOR COOLANT FLOW..............63
REMOVAL..............................63
CLEANING..............................65
INSPECTION............................65
INSTALLATION...........................65
RADIATOR PRESSURE CAP
DESCRIPTION...........................65
OPERATION.............................65
DIAGNOSIS AND TESTING.................66
RADIATOR CAP-TO-FILLER NECK SEAL.....66
RADIATOR CAP........................66
CLEANING..............................66
INSPECTION............................66
WATER PUMP - 3.9L/5.2L/5.9L
DESCRIPTION...........................67
OPERATION.............................67
DIAGNOSIS AND TESTING.................67
WATER PUMP.........................67
REMOVAL..............................67
CLEANING..............................69INSPECTION............................69
INSTALLATION...........................70
WATER PUMP - 8.0L
DIAGNOSIS AND TESTING.................70
WATER PUMP.........................70
REMOVAL..............................70
CLEANING..............................72
INSPECTION............................72
INSTALLATION...........................72
WATER PUMP - 5.9L DIESEL
DESCRIPTION...........................73
OPERATION.............................73
DIAGNOSIS AND TESTING.................73
WATER PUMP.........................73
REMOVAL..............................73
CLEANING..............................73
INSPECTION............................73
INSTALLATION...........................74
WATER PUMP INLET TUBE - 3.9L/5.2L/5.9L
REMOVAL..............................74
INSTALLATION...........................77
COOLANT
DESCRIPTION
ETHYLENE-GLYCOL MIXTURES
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
The required ethylene-glycol (antifreeze) and water
mixture depends upon the climate and vehicle oper-
ating conditions. The recommended mixture of 50/50
ethylene-glycol and water will provide protection
against freezing to -37 deg. C (-35 deg. F). The anti-
freeze concentrationmust alwaysbe a minimum of
44 percent, year-round in all climates.If percentage
is lower than 44 percent, engine parts may be
eroded by cavitation, and cooling system com-
ponents may be severely damaged by corrosion.
Maximum protection against freezing is provided
with a 68 percent antifreeze concentration, which
prevents freezing down to -67.7 deg. C (-90 deg. F). A
higher percentage will freeze at a warmer tempera-
ture. Also, a higher percentage of antifreeze can
cause the engine to overheat because the specific
heat of antifreeze is lower than that of water.
Use of 100 percent ethylene-glycol will cause for-
mation of additive deposits in the system, as the cor-
rosion inhibitive additives in ethylene-glycol require
the presence of water to dissolve. The deposits act as
insulation, causing temperatures to rise to as high as
149 deg. C (300) deg. F). This temperature is hot
enough to melt plastic and soften solder. Theincreased temperature can result in engine detona-
tion. In addition, 100 percent ethylene-glycol freezes
at 22 deg. C (-8 deg. F ).
PROPYLENE-GLYCOL MIXTURES
It's overall effective temperature range is smaller
than that of ethylene-glycol. The freeze point of 50/50
propylene-glycol and water is -32 deg. C (-26 deg. F).
5 deg. C higher than ethylene-glycol's freeze point.
The boiling point (protection against summer boil-
over) of propylene-glycol is 125 deg. C (257 deg. F )
at 96.5 kPa (14 psi), compared to 128 deg. C (263
deg. F) for ethylene-glycol. Use of propylene-glycol
can result in boil-over or freeze-up on a cooling sys-
tem designed for ethylene-glycol. Propylene glycol
also has poorer heat transfer characteristics than
ethylene glycol. This can increase cylinder head tem-
peratures under certain conditions.
Propylene-glycol/ethylene-glycol Mixtures can cause
the destabilization of various corrosion inhibitors,
causing damage to the various cooling system compo-
nents. Also, once ethylene-glycol and propylene-glycol
based coolants are mixed in the vehicle, conventional
methods of determining freeze point will not be accu-
rate. Both the refractive index and specific gravity dif-
fer between ethylene glycol and propylene glycol.
OPERATION
Coolant flows through the engine block absorbing the
heat from the engine, then flows to the radiator where
the cooling fins in the radiator transfers the heat from
the coolant to the atmosphere. During cold weather the
ethylene-glycol coolant prevents water present in the
cooling system from freezing within temperatures indi-
cated by mixture ratio of coolant to water.
7 - 40 ENGINEBR/BE
Page 376 of 2889

COOLANT RECOVERY
CONTAINER - 3.9L/5.2L/5.9L/
5.9L DIESEL
DESCRIPTION
The coolant reserve/overflow tank is mounted to
the side of the fan shroud (Fig. 1), and is made of
high temperature plastic.
OPERATION
The coolant reserve/overflow system works in con-
junction with the radiator pressure cap. It utilizes
thermal expansion and contraction of coolant to keep
coolant free of trapped air. It provides a volume for
expansion and contraction of coolant. It also provides
a convenient and safe method for checking coolant
level and adjusting level at atmospheric pressure.
This is done without removing the radiator pressurecap. The system also provides some reserve coolant
to the radiator to cover minor leaks and evaporation
or boiling losses.
As the engine cools, a vacuum is formed in the
cooling system of both the radiator and engine. Cool-
ant will then be drawn from the coolant tank and
returned to a proper level in the radiator.
REMOVAL
(1) Remove overflow hose from radiator.
(2) Unsnap the coolant reserve/overflow tank from
fan shroud. Lift straight up. The fan shroud is
equipped with T-shaped slots (Fig. 2) to attach the
tank. An alignment pin is located on the side of tank.
INSTALLATION
(1) Snap the tank into the two T-slots and the
alignment pin on fan shroud (Fig. 3).
(2) Connect overflow hose to radiator.
Fig. 1 Coolant Reserve/Overflow Tank
1 - T-SLOTS
2 - ALIGNMENT PIN
3 - FAN SHROUD
4 - COOLANT RESERVE/OVERFLOW TANK
Fig. 2 COOLANT RESERVE/OVERFLOW TANKÐALL
EXCEPT 8.0L V-10 ENGINE
1 - T-SLOTS
2 - ALIGNMENT PIN
3 - FAN SHROUD
4 - COOLANT RESERVE/OVERFLOW TANK
BR/BEENGINE 7 - 41