engine coolant CHEVROLET DYNASTY 1993 User Guide

INSTALLATIONÐ3.3L AND 3.8L ENGINE
Place a new gasket (dipped in water) on the water
box surface, center thermostat into opening in the in-
take manifold. Place housing over gasket and ther-
mostat, making sure thermostat is in recess provided
(Fig. 13). Bolt housing to intake manifold, tighten
bolts to 28 N Im (250 in. lbs.). Refill cooling system
(see Refilling System ).
COOLANT
The cooling system is designed around the coolant.
The coolant must accept heat from engine metal, in
the cylinder head area near the exhaust valves. Then
carry this heat to the radiator where the tube/fin as-
semblies of these components can give it up to the
air.
PERFORMANCE
Performance is measurable. For heat transfer pure
water excels (Formul a = 1 btu per minute for each
degree of temperature rise for each pound of water).
This formula is altered when necessary additives to
control boiling, freezing, and corrosion are added as
follows:
² Pure Water (1 btu) boils at 100ÉC (212ÉF) and
freezes at 0ÉC (32ÉF).
² 100 Percent Glycol (.7 btu) can cause a hot engine
and detonation and will raise the freeze point to 22ÉC
(-8ÉF).
² 50/50 Glycol and Water (.82 btu) is the recom-
mended combination that provides a freeze point of
-37ÉC(-35ÉF).The radiator, water pump, engine water
jacket, radiator pressure cap, thermostat, tempera-
ture gauge, sending unit and heater are all designed
for 50/50 glycol. Where required, a 56 percent glycol and 44 percent
water mixture will provide a freeze point of-59ÉC
(-50ÉF).
CAUTION: Richer mixtures cannot be measured
with field equipment which can lead to problems
associated with 100 percent glycol.
SELECTION AND ADDITIVES
The use of aluminum cylinder heads, intake mani-
folds, and water pumps requires special corrosion
protection. Mopar Antifreeze, Prestone II, Peak or
antifreeze containing Alugard 340-2, or their equiva-
lent are recommended for best engine cooling with-
out corrosion. When mixed only to a freeze point of
Fig. 11 Thermostat, Housing, and Water BoxÐ3.0L Engine
Fig. 12 Thermostat InstalledÐ3.0L Engine
Fig. 13 Thermostat, Housing and WaterboxÐ3.3Land 3.8L Engine
7 - 14 COOLING SYSTEM Ä

-37ÉC (-35ÉF) to -59ÉC (-50ÉF). If it looses color or
becomes contaminated, drain, flush, and replace with
fresh properly mixed solution.
SERVICE
Coolant should be changed at 52,500 miles or three
years, whichever occurs first, then every two years or
30,000 miles.
ROUTINE LEVEL CHECK
Do not remove radiator cap for routine coolant
level inspections. The coolant reserve system provides a quick visual
method for determining the coolant level without re-
moving the radiator cap. Simply observe, with the
engine idling and warmed up to normal operating
temperature, that the level of the coolant in the reserve
tank (Figs. 5 and 6) is between the minimum and
maximum marks.
ADDING ADDITIONAL COOLANT
The radiator cap should not be removed. When
additional coolant is needed to maintain this level, it
should be added to the coolant reserve tank. Use only
50/50 concentration of ethylene glycol type antifreeze
and water.
SERVICE COOLANT LEVEL
The cooling system is closed and designed to main-
tain coolant level to the top of the radiator. When servicing requires a coolant level check in the
radiator, the engine must be offand notunder pres-
sure. Drain several ounces of coolant from the radiator
drain cock while observing the Coolant Recovery Sys-
tem (CRS) Tank. Coolant level in the CRS tank should
drop slightly. Then remove the radiator cap. The radia-
tor should be full to the top. If not, and the coolant level
in the CRS tank is at the MIN mark there is a air leak
in the CRS system. Check hose or hose connections to
the CRS tank, radiator filler neck or the pressure cap
seal to the radiator filler neck for leaks.
LOW COOLANT LEVEL AERATION
Low coolant level in a cross flow radiator will equal-
ize in both tanks with engine off. With engine at
running operating temperature the high pressure inlet
tank runs full and the low pressure outlet tank drops.
If this level drops below the top of the transmission oil
cooler, air will be sucked into the water pump:
² Transmission oil will become hotter.
² High reading shown on the temperature gauge.
² Air in the coolant will also cause loss of flow through
the heater.
² Exhaust gas leaks into the coolant can also cause the
same problems.
DEAERATION
Air can only be removed from the system by gather-
ing under the pressure cap. On the next heat up it will
be pushed past the pressure cap into the CRS tank by
thermal expansion of the coolant. It then escapes to the
atmosphere in the CRS tank and is replaced with solid
coolant on cool down.
COOLING SYSTEM DRAIN, CLEAN, FLUSH AND
REFILL
Drain, flush, and fill the cooling system at the
mileage or time intervals specified in the Maintenance
Schedule in this Group. If the solution is dirty or rusty
or contains a considerable amount of sediment, clean
and flush with a reliable cooling system cleaner. Care
should be taken in disposing of the used engine coolant
from your vehicle. Check governmental regulations for
disposal of used engine coolant.
DRAINING
To drain cooling system move temperature selector
for heater to full heat with engine running (to provide
vacuum for actuation). Without removing radiator
pressure cap and with system not under pres-
sure, Shut engine off and open draincock. The coolant
reserve tank (Fig. 5) should empty first, then remove
radiator pressure cap. (if not, see Testing Cooling
System for leaks). To vent 2.2/2.5L engines remove the
plug above thermostat housing (Fig. 1). For Turbo III
engines remove coolant temperature sensor in the
thermostat housing (Fig. 2). For 3.3L /3.8L engine
remove the engine temperature sending unit (Fig. 3).
Removal of a plug or other component is required
because the thermostat has no air vent and prevents
air flow through it. This allows the coolant to drain
from the engine block.
Fig. 1 Thermostat Housing Drain/Fill PlugÐ2.2/2.5L Engines
Ä COOLING SYSTEM 7 - 15

CLEANING
Drain cooling system (see: Draining Cooling Sys-
tem ) and refill with clean water (see: Refilling
Cooling System ). Run engine with radiator cap in-
stalled until upper radiator hose is hot. Stop engine
and drain water from system. If water is dirty, fill,
run and drain system again until water runs clear.
REVERSE FLUSHING
Reverse flushing of the cooling system is the forc-
ing of water through the cooling system, using air
pressure in a direction opposite to that of the normal
flow of water. This is only necessary with dirty sys-
tems and evidence of partial plugging.
RADIATOR Drain cooling system and remove radiator hoses
from engine. Install suitable flushing gun in radiator
lower hose. Fill radiator with clean water and turn
on air in short blasts. CAUTION: Internal radiator pressure must not ex-
ceed 138 kPa (20 psi) as damage to radiator may re-
sult. Continue this procedure until water runs clear.
ENGINE
Drain radiator (see: Draining Cooling System )
and remove hoses from radiator. Remove engine
thermostat and reinstall thermostat housing. Install
suitable flushing gun to thermostat housing hose.
Turn on water, and when engine is filled, turn on
air, but no higher than 138 kPa (20 psi) in short
blasts. Allow engine to fill between blasts of air.
Continue this procedure until water runs clean. In-
stall thermostat using a new housing gasket. Fill
cooling system (See Refilling Cooling System ).
CHEMICAL CLEANING
One type of corrosion encountered with aluminum
cylinder heads is aluminum hydroxide deposits. Cor-
rosion products are carried to the radiator and depos-
ited when cooled off. They appear as dark grey when
wet and white when dry. This corrosion can be re-
moved with a two part cleaner (oxalic acid and neu-
tralizer) available in auto parts outlets. Follow
manufacturers directions for use.
REFILLING
First clean system to remove old glycol, see Cooling
System Cleaning. Fill system using antifreeze described in Coolant
section. Fill 50 percent of capacity with 100 percent
glycol. Then complete filling system with water. The
2.2/2.5L engines require venting by removal of the
plug on top of the water box (Fig. 1). Turbo III en-
gines require venting by removing the coolant tem-
perature sensor on top of the thermostat housing
(Fig. 2). The 3.3/3.8L Engines require removal of the
Engine Temperature Sending Unit on the front of
the cylinder head (Fig. 3). The thermostat in these
engines do not allow air flow through them. When
coolant reaches the vent holes;
² Install vent plug and tighten to 20 N Im (15 ft. lbs.)
for 2.2/2.5L Engines.
² Install Coolant Temperature Sensor and tighten to
27 N Im (20 ft. lbs.) for Turbo III Engine.
² Install Engine Temperature Sending Unit and
tighten to 7 N Im (60 in. lbs.) for 3.3/3.8L Engines.
Continue filling system until full, this provides bet-
ter heater performance. Be careful not to spill
coolant on drive belts or the generator. Fill coolant reserve system to at least the MAX
mark with 50/50 solution. It may be necessary to add
coolant to the reserve tank to maintain coolant level
between the MAX and MIN mark after three or four
warm-up, cool down cycles and trapped air has been
removed.
Fig. 2 Coolant Temperature SensorÐTurbo III Drain/Fill
Fig. 3 Engine Temperature Sending UnitÐ3.3L and 3.8L Drain/Fill
7 - 16 COOLING SYSTEM Ä

TESTING SYSTEM FOR LEAKS
With engine not running, wipe the radiator filler
neck sealing seat clean. The radiator should be full. Attach a radiator pressure tester to the radiator, as
shown in (Fig. 4) and apply 104 kPa (15 psi) pres-
sure. If the pressure drops more than 2 psi in 2 min-
utes inspect all points for external leaks. All hoses, radiator and heater, should be moved
while at 15 psi since some leaks occur while driving
due to engine rock, etc.
If there are no external leaks after the gauge dial
shows a drop in pressure, detach the tester. Start en-
gine and run the engine to normal operating temper-
ature in order to open the thermostat and allow the
coolant to expand. Re-attach the tester. If the needle
on the dial fluctuates it indicates a combustion leak,
usually a head gasket leak.
WARNING: WITH TOOL IN PLACE PRESSURE
BUILDS UP FAST. ANY EXCESSIVE AMOUNT OF
PRESSURE BUILT UP BY CONTINUOUS ENGINE
OPERATION MUST BE RELEASED TO A SAFE
PRESSURE POINT. NEVER PERMIT PRESSURE TO
EXCEED 138 KPA (20 PSI).
If the needle on the dial does not fluctuate, race
the engine a few times. If an abnormal amount of
coolant or steam is emitted from the tail pipe, it may
indicate a faulty head gasket, cracked engine block
or cylinder head. There may be internal leaks which can be deter-
mined by removing the oil dip-stick. If water glob-
ules appear intermixed with the oil it will indicate a internal leak in the engine. If there is an internal
leak, the engine must be disassembled for repair.
COOLANT RECOVERY SYSTEM (CRS)
This system works in conjunction with the radiator
pressure cap to utilize thermal expansion and con-
traction of the coolant to keep the coolant free of
trapped air. It provides a volume for expansion and
contraction, provides a convenient and safe method
for checking coolant level and adjusting level at at-
mospheric pressure without removing the radiator
pressure cap. It also provides some reserve coolant to
cover minor leaks and evaporation or boiling losses.
All vehicles are equipped with this system (Figs. 5
and 6).
See Coolant Level Check Service, Deaeration and
Pressure Cap sections for operation and service. Ve-
hicles equipped with the electric monitor system use
a level sensor in the CRS tank, see Group 8E Elec-
trical for service.
Fig. 4 Pressure Testing Cooling System
Fig. 5 Coolant Recovery System Typical
Fig. 6 Coolant Recovery SystemÐAC-AY Models
Ä COOLING SYSTEM 7 - 17

RADIATOR PRESSURE CAP
Radiators are equipped with a pressure cap which
releases pressure at some point within a range of
97-124 kPa (14-18 psi) (Fig. 7). The system will operate at higher than atmospheric
pressure which raises the coolant boiling point allow-
ing increased radiator cooling capacity. There is also a vent valve in the center of the cap that
allows a small coolant flow to the CRS tank. If valve is
stuck shut, the radiator hoses will be collapsed
on cool down. Clean the vent valve (Fig. 7) to
ensure proper sealing when boiling point is
reached.
There is also a gasket in the cap to seal to the top of
the filler neck so that vacuum can be maintained for
drawing coolant back into the radiator from the coolant
reserve system tank.
RADIATOR CAP TO FILLER NECK SEAL PRES- SURE RELIEF CHECK
The pressure cap upper gasket (seal) pressure relief
can be checked by removing the overflow hose at the
radiator filler neck nipple (Fig. 7). Attach the Radiator
Pressure Tool to the filler neck nipple and pump air
into the radiator. Pressure cap upper gasket should
relieve at 69-124 kPa (10-18 psi) and hold pressure at
55 kPa (8 psi) minimum.
WARNING: THE WARNING WORDS DO NOT OPEN
HOT ON THE RADIATOR PRESSURE CAP IS A
SAFETY PRECAUTION. WHEN HOT, PRESSURE
BUILDS UP IN COOLING SYSTEM. TO PREVENT
SCALDING OR INJURY, THE RADIATOR CAP
SHOULD NOT BE REMOVED WHILE THE SYSTEM IS
HOT AND/OR UNDER PRESSURE.
There is no need to remove the radiator cap at any
time except for the following purposes:
(1) Check and adjust antifreeze freeze point.
(2) Refill system with new antifreeze.
(3) Conducting service procedures.
(4) Checking for vacuum leaks.
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT 15 MINUTES BEFORE REMOVING CAP. THEN PLACE A SHOP TOWEL OVER THE CAP AND WITH-
OUT PUSHING DOWN ROTATE IT COUNTER-
CLOCKWISE TO THE FIRST STOP. ALLOW FLUIDS
TO ESCAPE THROUGH THE OVERFLOW TUBE AND
WHEN THE SYSTEM STOPS PUSHING COOLANT
AND STEAM INTO THE CRS TANK AND PRESSURE
DROPS PUSH DOWN AND REMOVE THE CAP COM-
PLETELY. SQUEEZING THE RADIATOR INLET HOSE
WITH A SHOP TOWEL (TO CHECK PRESSURE) BE-
FORE AND AFTER TURNING TO THE FIRST STOP IS
RECOMMENDED.
PRESSURE TESTING RADIATOR CAPS
Dip the pressure cap in water, clean any deposits off
the vent valve or its seat and apply cap to end of
Radiator Pressure Tool. Working the plunger, bring the
pressure to 104 kPa (15 psi) on the gauge. If the
pressure cap fails to hold pressure of at least 97 kPa
(14 psi) replace cap. See CAUTION
If the pressure cap tests properly while positioned on
Radiator Pressure Tool, but will not hold pressure or
vacuum when positioned on the radiator. Inspect the
radiator filler neck and cap top gasket for irregularities
that may prevent the cap from sealing properly.
CAUTION: Radiator Pressure Tool is very sensitive to
small air leaks which will not cause cooling system
problems. A pressure cap that does not have a
history of coolant loss should not be replaced just
because it leaks slowly when tested with this tool.
Add water to the tool. Turn tool upside down and
recheck pressure cap to confirm that cap is bad.
INSPECTION
Hold the cap in hand, right side up(Fig. 7). The
vent valve at the bottom of the cap should open. If the
rubber gasket has swollen and prevents the valve from
opening, replace the cap. Hold the cleaned cap in hand upside down.If any
light can be seen between vent valve and rubber
gasket, replace cap. Do not use a replacement cap
that has a spring to hold the vent shut. Replacement cap must be of the type designed for
coolant reserve systems. This design assures coolant
return to radiator.
RADIATORS
The radiators are crossflow types (horizontal tubes)
with design features that provide greater strength as
well as sufficient heat transfer capabilities to keep the
engine satisfactorily cooled.
CAUTION: Plastic tanks, while stronger then brass
are subject to damage by impact, such as wrenches.
Fig. 7 Radiator Pressure Cap Filler Neck
7 - 18 COOLING SYSTEM Ä

RADIATOR DRAINCOCK SERVICE
REMOVAL (1) Turn the drain cock stem counterclockwise to
unscrew the stem. When the stem is unscrewed to
the end of the threads, pull the stem (Fig. 10) from
the radiator tank.
INSTALLATION (1) Push the draincock assembly body into the
tank opening until it snaps into place. (2) Tighten the draincock stem by turning clock-
wise to 2.0-2.7 N Im (18-25 in. lbs.) torque.
RADIATOR COOLANT FLOW CHECK
To determine whether coolant is flowing through
the cooling system, use the following procedure: (1) If engine is cold, idle engine until normal oper-
ating temperature is reached. Then feel the upper ra-
diator hose. If it is hot, coolant is circulating.
WARNING: DO NOT REMOVE RADIATOR PRES-
SURE CAP WITH THE SYSTEM HOT AND UNDER
PRESSURE BECAUSE SERIOUS BURNS FROM
COOLANT CAN OCCUR.
Fig. 9 Cooling ModuleÐTypical
Fig. 8 Pressure Testing Radiator Cap
Fig. 10 Draincock AssemblyÐTypical
Ä COOLING SYSTEM 7 - 19

(2) Remove radiator pressure cap when engine is
cold, Idle engine until thermostat opens, you should
observe coolant flow while looking down the filler
neck. Once flow is detected install radiator pressure
cap.
RADIATOR
REMOVAL
(1) Disconnect negative battery cable from battery.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK PLUG OR THE RADIATOR DRAINCOCK
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
(2) Drain cooling system. Refer to Draining Cool-
ing System of this section. (3) Remove hose clamps and hoses from the radia-
tor (Fig. 11). Remove coolant reserve system tank to
filler neck tube. (4) Remove automatic transmission hoses, if
equipped. (5) Remove fan and fan support assembly by dis-
connecting fan motor electrical connector. Remove
fan shroud retaining clips, located on the top and
bottom of the shroud for AA, AG, AJ and AP vehi-
cles. AC/AY vehicle retainer clips are located on the
top only. Lift shroud up and out of bottom shroud at-
tachment clips separating shroud from radiator. Fan
damage should always be avoided. (6) Remove upper radiator mounting screws. Dis-
connect the engine block heater wire if equipped. (7) Remove the air conditioning condenser attaching
screws located at the top front of the radiator,if
equipped. Radiator can now be lifted free from engine compart-
ment. Care should be taken not to damage radia-
tor cooling fins or water tubes during removal.
INSTALLATION
(1) Slide radiator down into position behind radiator
support (yoke). (2) Attach air conditioning condenser to radiator, if
equipped, with a force of approximately 10 lbs. to seat
the radiator assembly lower rubber isolators in the
mount holes provided. (3) Tighten radiator mounting screws to 11.9N Im
(105 in. lbs.). (4) Connect automatic transmission hoses, if
equipped. Tighten hose clamps to 4 N Im (35 in. lbs.).
(5) Slide fan shroud, fan and motor down into clips
on lower radiator flange. Replace shroud retaining
clips. (6) Install upper and lower radiator hoses (including
coolant reserve hose). (7) Connect fan motor electrical connection and con-
nect negative battery cable. (8) Fill cooling system with coolant. Refer to Refill-
ing Cooling Systems. in this group.
(9) Operate engine until it reaches normal operating
temperature. Check cooling system and automatic
transmission for correct fluid levels.
Fig. 11 Cooling ModulesÐAll Models
7 - 20 COOLING SYSTEM Ä

RADIATOR HOSES
The hoses are removed using Constant Tension
Clamp pliers to compress hose clamp. A hardened, cracked, swollen or restricted hose
should be replaced. Do not damage radiator inlet and
outlet when loosening hoses. Radiator hoses should be routed without any kinks
and indexed as designed. The use of molded hoses is
recommended. Spring type hose clamps are used in all applica-
tions. If replacement is necessary replace with the
original style spring type clamp.
FANS
All models use electric motor driven cooling system
fans. The fan modules include a motor support which
may (depending on model) include a shroud. The
module is fastened to the radiator by screws with
U-nuts and retaining clips (Fig. 12). All fan motors are one speed. Attempts to reduce
high temperature gauge reading by increasing en-
gine speed, at the same vehicle speed, can increase
high temperature.
SINGLE FAN
There are no repairs to be made to the fan. If the
fan is warped, cracked, or otherwise damaged, it must be replaced with
onlythe recommended part for
adequate strength, performance and safety (Fig. 13).
DUAL FAN MODULEÐAC/AY BODY
The dual fan module (Fig. 11) is a combination of 2
fans mounted in a one piece shroud which are simul-
taneously activated. The dual fan system improves
engine cooling and air conditioning performance in hot
weather and severe driving conditions, while reducing
fan noise and power consumption.
REMOVAL
Disconnect electric motor lead. Remove fan module
to radiator fasteners and retaining clips. Remove as-
sembly from radiator support. To remove fan from motor shaft, bench support the
motor and motor shaft, while removing the fan retain-
ing clip, so that the shaft and motor will not be
damaged by excessive force. Surface or burr re-
moval may be required to remove fan from motor
shaft. (Fig. 13). Do not permit the fan blades to touch
the bench.
INSTALLATION
Slide the fan on motor shaft. Support motor and
shaft as above while installing fan retaining clip.
Install assembly into pocket on lower radiator tank.
Attach retaining clips and fasteners to radiator tank.
Right side fastener is longer on A/C equipped
vehicles . Connect fan motor lead. For wiring dia-
grams of fan motor systems see Wiring Diagrams
Manual
RADIATOR FAN CONTROLÐALL EXCEPT V-6 ENGINE
Fan control is accomplished two ways. The fan al-
ways runs when the air conditioning compressor
clutch is engaged. In addition to this control, the fan is
turned on by the temperature of the coolant which is
sensed by the coolant temperature sensor which
Fig. 12 Servicing Fan Module
Fig. 13 Radiator Fan Retaining ClipÐTypical
Ä COOLING SYSTEM 7 - 21

sends the message to the Engine Controller. The En-
gine Controller turns on the fan through the fan re-
lay. See Wiring Diagrams Manual for circuity and
diagnostics provided.Switching through the Engine Controller provides
fan control for the following conditions.
² The fan will not run during cranking until the en-
gine starts no matter what the coolant temperature
is.
² Fan will run when the air conditioning clutch is
engaged and low pressure cutout switch is closed.
² For 4 cylinder application the fan will run at ve-
hicle speeds above about 40 mph only if coolant tem-
perature reaches 110ÉC (230ÉF). It will turn off when
the temperature drops to 104ÉC (220ÉF). At speeds
below 40 mph the fan switches on at 102ÉC (215ÉF)
and off at 93ÉC (200ÉF).
² This is to help prevent steaming. The fan will run
only below 16ÉC (60ÉF) ambient. Between 38ÉC
(100ÉF) to 97ÉC (195ÉF) coolant temperature, at idle
and then only for three minutes.
RADIATOR FAN CONTROLÐAC/AY BODY V-6 ONLY
For this application, fan control is accomplished
based on coolant temperature, and on A/C head pres-
sure. These vehicles receive the variable displace-
ment compressor. The fan will go on when;
² Coolant temperature reaches 102ÉC (215ÉF) and off
at 93.4ÉC (200ÉF) regardless of vehicle speed.
² When the head pressure reaches 1516.9 kPa (220
psi) and turn off when the pressure reaches 1103 kPa
(160 psi).
TEMPERATURE GAUGE INDICATION
At idle the temperature gauge will rise slowly to
about 5/8 gauge travel. The fan will come on and the
gauge will drop to about 1/2 gauge travel, this is nor-
mal.
ELECTRIC FAN MOTOR
To check out the electric fan motor, disconnect the
fan motor wire connector and connect it with #14
gauge wires to a good 12-volt battery observing cor-
rect polarity per (Fig. 14). If the fan runs normally,
the motor is functioning properly. If not, replace fan
module using the removal and installation instruc-
tions contained in the Fan Section. If the motor is
noticeably overheated (i.e.; wire insulation melted,
motor charred) the system voltage may be too high.
Check charging system, see Group 8A, Battery/Start-
ing/Charging System Diagnostics.
ELECTRIC FAN MOTOR TEST
Equipment required
² Diagnostic Tool DRB II or equivalent
² Volt/Ohm Meter
² Wiring Diagram Manual (1) Run the engine to normal operating tempera-
ture. (2) Check wiring connector in C25, C9, and C26 for
proper engagement, see Wiring Diagram Manual (3) Using a diagnostic tool, plugged into the diag-
nostic connector rearward of the battery, check the
On-Board Diagnostics (OBD) in the Engine Control-
ler for fault codes, see Group 14, Fuel Injection for
instructions. (4) If fault code 88-12-35-55 is detected, proceed to
Step 5. (5) With the ignition switch in the run position,
test for battery voltage (single pin connector) at the
fan relay. Voltage reading OK, proceed to Step 6a.
Voltage at 0-1 volt, proceed to Step 6b. 6(a) With the ignition off, disconnect the 60-way
connector from the Engine Controller (outboard of
battery) and return the ignition to the run position.
Test for battery voltage at cavity 31 of the 60-way
connector (Fig. 15). Voltage reading OK and female
terminal is not damaged, replace the Engine Control-
ler. Voltage reading 0, repair open or short in C27
circuit. (b) With the ignition off, disconnect the 60-way
connector from the Engine Controller (outboard of
battery) and return the ignition to the run position.
Test for battery voltage at the single pin connector
at the fan relay. Voltage reading OK, replace the
Engine Controller. Voltage reading 0-1 volt, pro-
ceed to Step 7.
(7) With ignition in the run position, test for bat-
tery voltage at the wire (C27) in the 3-way connector
of the fan relay. Voltage reading OK, replace the fan
relay. Voltage reading 0, repair open or short in C27
circuit. (8) Turn ignition off, connect the 60-way connector
at the Engine Controller and test the system.
Fig. 14 Electric Fan MotorÐTypical
7 - 22 COOLING SYSTEM Ä

FAN SHROUD
All vehicles have fan shrouds to improve fan air
flow efficiency. These fan shrouds cover less than full
radiator frontal area to prevent the shroud from re-
stricting air flow at high speeds. The shroud supports the electric fan motor and fan.
For removal and installation see Radiator Section.
AUTOMATIC TRANSMISSION OIL COOLERS
Oil coolers are internal oil to coolant type, mounted
in the radiator left tank (Fig. 16). Rubber oil lines
feed the oil cooler and the automatic transmission.
Use only approved transmission oil cooler hose. Since
these are molded to fit space available, molded hoses
are recommended. Tighten Oil Cooler Hose Clamps
to4N Im (35 in. lbs.).
Fig. 15 Engine Controller 60-Way Connector from
Terminal End
Fig. 16 Transmission Oil Cooler
Ä COOLING SYSTEM 7 - 23