1988 PONTIAC FIERO Service Repair Manual

6B-8 ENGINE COOLING
PROBLEMS NOT REQUIRING DISASSEMBLY OF COOLING SYSTEM - 1. LARGE OBSTRUCTIONS BLOCKING RADIATOR OR CONDENSER
a. AUXILIARY OIL COOLERS
b. LICENSE PLATES R ELOCATE
c. SPARE TIRES
d. ICE, MUD OR SNOW OBSTRUCTING GRILLE - REMOVE
2. ENGINE OIL OVERFILL - CHECK ENGINE OIL DIPSTICK
3. WRONG RADIATOR FOR
APPLICATION - CHECK PART NO. AGAINST PARTS LlST
4. LOOSE, DAMAGED OR MISSING AIR SEALS - SEE BODY SERVICE MANUAL
5. MISSING OR DAMAGED LOWER AIR BAFFLE - SEE BODY SERVICE MANUAL
6. WRONG IGNITION TIMING - SEE CHASSIS SERVICE MANUAL PROBLEMS REQUIRING DISASSEMBLY OF COOLING SYSTEM -
1. INCORRECT OR DAMAGED FAN - CHECK PART NO. AGAINST PARTS LlST
2. FAULTY EMISSION SYSTEM COMPONENTS (COULD CAUSE OVERHEATING AT IDLE)
; SEE CHASSIS SERVICE MANUAL
3. PRESSURE CHECK COOLING SYSTEM WITH PRESSURE CAP INSTALLED - WILL SHOW
IF PRESSURE CAP LEAKS BECAUSE OF RADIATOR FILLER NECK DAMAGE
4. DEFECTIVE WATER PUMP
a. ERODED OR BROKEN IMPELLER VANES
b. FAILED BEARING OR SEAL - CHECK FOR SHAFT OR BEARING PLAY
5. PLUGGED RADIATOR TUBES - SEND TO RADIATOR REPAIR SHOP FOR FLOW CHECK
6. INTERNAL SYSTEM LEAKS
B. HEAD GASKET - SEE CHASSIS SERVICE MANUAL
b. CRACKED BLOCK
c. TIMING CHAIN COVER
d. INTAKE MANIFOLD GASKET
7. PLUGGED COOLANT PASSAGES IN CYLINDER HEADS - REMOVE HEADS AND CHECK VISUALLY
Fig. 6 Cooling System Diagnosis Chart (3 of 3)
1. RELIEVE PRESSURE AND CAREFULLY REMOVE RADIATOR CAP.
2. RUB W'F. TEMPERATURE STICK* ONTO THERMOSTAT MOUSING.
3. WARM UP ENGINE AT FAST IDLE:
WATCH FOR COOLANT FLOW BEFORE MAR
NO COOLANT FLOW INSTALL NEW
THERMOSTAT.
COLD ENGINE -SLOW WARMUP -NOT ENOUGH HEAT
1. RELIEVE PRESSURE AND CAREFULLY REMOVE RADIATOR CAP.
2. RUB 188'~. TEMPERATURE STICK' ONTO THERMOSTAT HOUSING.
3. WARM UP ENGINE AT FAST IDLE.
COOLANT FLOW
- 'NOTE: THE TEMPERATURE STICK IS A PENCIL LIKE DEVICE WHICH HAS A WAX MATERIAL CONTAINING CERTAIN CHEMICALS WHICH MELT AT A GIVEN TEMPERATURE THEWERATURE STICKS CAN BE USED TO DETERMINE A THERMOSTAT'S OPERATING TEMPERATURE BY RUBBING laB°F AN0 =OF. STICKS ON THE THERMOSTAT HOUSING. THE MARKS MADE BY THE STICKS SHOULD MELT WHEN COOLANT TEMPERATURES OF IWOF'AND W'F. ARE REACHED, RESPECTIVELY. THESE TEMPERATURES ARE THE NORMAL WERATING RANGE OF THE THERMOSTAT. THEREFORE, ~i WE COOLANT FLOWS AS INDICATED ON THE DIAGNOSIS CHART. THE THERMOSTAT MAY BE DEFECTIVE.
Fig. 7 Thermostat Diagnosis Chart

ENGINE COOLING BB-7
NOTICE: If recommended quality antifreeze is
used, supplemental inhibitors or additives claiming
to provide increased cooling capability are not
necessary. They may be detrimental to the efficient
operation of the system, and represent an
unnecessary operating expense.
Every 12 months or 15,000 miles, the cooling
system should be serviced as follows;
1. Wash radiator cap and filler neck with clean
water.
2. Check coolant for proper level and freeze
protection.
3. Pressure test system and radiator cap for proper
pressure holding capacity, 103
kPa (15 psi). If
replacement of cap is required, use the proper cap
specified for car model.
4. Tighten hose clamps and inspect all hoses. Replace
hoses whenever cracked, swollen or otherwise
deteriorated.
5. Clean frontal area of radiator core and air
conditioning condenser.
DRAINING AND REFILLING THE COOLING
SYSTEM
Replace hoses every 24 months or 30,000 miles or
earlier if cracked, swollen or otherwise deteriorated.
Every two years or 30,000 miles, whichever first
occurs, the cooling system should be flushed and
refilled using the following recommended procedure:
1. Remove radiator cap, or thermostat housing cap
(VIN
0, J, R and U), when engine is cool by:
a. Slowly
rotating cap counterclockwise to
detent. (Do not press down while rotating.)
b. Wait until any
residual pressure (indicated
by a hissing sound) is relieved.
c. After all hissing ceases, press down on cap
while continuing to rotate
counterclockwise.
CAUTION: To avoid the danger of
being burned, do not remove radiator
cap while engine and radiator are still
hot. Scalding fluid and steam may be
blown out under pressure.
2. Remove the thermostat by using the wire handle
to lift it out of the housing (VIN
0, J, R and U).
3. With the thermostat removed, reinstall the
thermostat housing cap (VIN
0, J, R and U).
4. Open radiator drain valve and block drain plugs
to drain coolant. On VIN R and
9 (P series)
engines, open coolant pipe plugs.
5. Close valve. Reinstall drain plugs, and add
sufficient water to fill system.
6. Run engine, drain and refill the system, as
described in steps
4 and 5 a sufficient number of
times, until the drained liquid is nearly colorless.
Important
BLOCK DRIVE WHEELS, place
transmission in PARK (automatic
transmission) or NEUTRAL (manual
transmission) and set the parking brake. 7.
Allow system to drain completely. Then close
radiator drain valve tightly, and reinstall block
drain plugs.
8. Remove recovery cap leaving hoses in place.
Remove coolant recovery tank and empty of
fluid. Flush tank with clean water, drain and
reinstall.
9. Add sufficient ethylene glycol coolant, meeting
GM specification 1825-M, to provide the
required freezing and corrosion protection
- at
least 50 percent solution -37°C (-34°F). Fill
radiator to the base of the radiator fill neck and
add sufficient coolant to the recovery tank to
raise level to the "FULL" mark. Reinstall
recovery tank cap.
10. Run engine, with radiator cap or thermostat
housing cap removed, until normal operating
temperature is reached. (Radiator upper hose
becomes hot.)
11. With engine idling, add coolant until level
reaches bottom of filler neck and reinstall cap,
making certain arrows line up with overflow tube.
CAUTION: Under some conditions, the
ethylene glycol in engine coolant is
flammable. To help avoid being
burned when adding coolant, DO NOT
spill
it on the exhaust system or hat
engine parts.
It is the owner's responsibility to keep the freeze
protection at a level appropriate to the
temperatures which may occur in the area of
vehicle operation.
a. Maintain
cooling system freeze protection
at
-37°C (-34"F), to ensure protection
against corrosion and loss of coolant from
boiling, even though freezing temperatures
are not expected.
b. Add ethylene glycol base coolant that meets
GM Specification 1825-M, when coolant
additions are required because of coolant
loss, or to provide additional protection
against
freezing at temperatures lower than
-37°C (-34°F).
NOTICE: Alcohol or methanol base coolants, or
plain water, are not recommended at any time.
DRlVE BELT
NOTICE: Routine inspection of the belt may
reveal cracks in the belt ribs. These cracks will
not impair belt performance and therefore should
not be considered a problem requiring belt
replacement. However, the belt should be
replaced if belt slip occurs or if sections of the
belt ribs are missing.
A single (serpentine) belt is used to drive all
engine accessories formerly driven by multiple drive
belts. All belt driven accessories are ridgedly mounted
with belt tension maintained by a spring loaded
tensioner.
The drive belt tensioner has the ability to control
belt tension over a fairly broad range of belt lengths.

68-8 ENGINE COOLING
However, there are limits to the tensioner's ability to
The tensioner has rovisions for a visual check to
compensate for varying lengths of belts. With the
ten- verify that it is in t e "operating range" (see Figures
sioner outside of its operating range, poor tension
608 and 609). R
control andlor damage to the tensioner may result.
ALUMINUM RADIATOR REPAIR
This radiator utilizes an aluminum core with
plastic side tanks. The core and side tanks can be
replaced separately and core repair is easily made with
the hot melt adhesive method. A transaxle oil cooler
is located in one of the side tanks. The oil cooler can
be replaced. The drain cock is located on the lower part
of one of the tanks. The drain cock is also serviceable.
Core
The core is made of aluminum and is of the
crossflow design. It utilizes large tubes that resist
plugging, and repairs to the tubes and core are easily
made using the hot melt adhesive method.
The core is attached to the tanks by clinched tabs
on the core that can be bent back if tank or core
replacement is required.
If the damage to a tube is too severe, a tube can
be blocked or plugged as explained in "Tube Blocking.
" No more than two tubes should ever be blocked on
a core. Also replace the core if more than three tabs are
broken on one side, or if two adjacent tabs are broken.
Tanks
The tanks are attached to the core by the use of
clinched tabs. The clinched tabs can be bent back if the
tanks need to be removed from the core. Bend the tabs
back only enough to remove the tank. Overbending
will weaken the tabs.
A high temperature rubber gasket is used to seal
the mating surface between the core and the tank. (See
Fig. 8). The gasket must be replaced any time a tank
is removed from the core.
Transaxle Oil Cooler
The transaxle oil cooler is located in one of the
radiator side tanks. The oil cooler can be replaced by
removing the tank from the core.
A leaking oil cooler gasket can be replaced
without removing the tank from the core.
Drain Cock
The aluminum/plastic radiator utilizes a two
piece plastic drain cock and a rubber seal. The drain
cock is serviceable (See Fig.
9).
ALUMINUM RADIATOR SERVICE
The aluminum-plastic radiator can be repaired at
the dealership. The following components are easily
replaced:
e Core
e Tanks and gaskets
o Oil coolers and gaskets
e Drain cock and gasket The
tanks cannot be repaired if broken or
cracked. The radiator core can be replaced and the new
core used with the original tanks and oil cooler.
Precautions
As with all cooling system service, take measures
to prevent personal injury and damage to the system.
CAUTION: To help avoid the danger of
being burned, do not remove the
radiator cap while the engine and
radiator are
still hot. Scalding fluid
and steam can be blown out under
pressure if the
cap is taken off too
soon.
NOTICE: DO NOT USE "BOIL OUT" TANKS
OR VATS. Common service methods may
actually destroy an aluminum radiator. Caustic or
lye cleaning solutions must NOT be used for
aluminum radiators.
e Do not open the hood if you can see, or hear,
steam or coolant escaping from the engine
compartment.
e Do not remove radiator cap if radiator feels
warm.
e Do not remove the radiator cap or coolant
recovery tank cap if the coolant in the recovery
tank looks like it is boiling.
Wear eye protection.
e Wear gloves to protect your hands against
excessive heat, or the effects of chemicals on your
skin.
o Prevent dirt and water from entering the
transmission oil cooler.
e Do not use boil-out tanks, or vats, or other tanks
that have been used for copper and brass
radiators. The flux, acid, and caustic cleaners
remaining in these tanks will attack the
aluminum and cause radiator failure.
A separate
test tank containing clean water is strongly
recommended for servicing aluminum-plastic
radiators.
RIOTICE: Never use shop air that is not regulated
at
20 psi (138 kPa) to pressure test radiator.
Pressures over
20 psi (138 kPa) will damage the
radiator.
DIAGNOSIS
Leak Testing
Some core leaks can be detected by merely adding
water to the radiator. It is helpful to clean the core so
that the damaged area can be more easily found.

ENGINE COOLING 6B-9
Fig. 8 Aluminum Radiator
2 SEAL
3 BODY I
1. Remove
dirt and insects from the fins with a
common water hose without a nozzle. Excessive
water pressure could damage the fins.
2. Scrub the core with a soft-bristle brush using
clean, hot water, or hot water with a mild
detergent solution.
On-Vehicle Pressure Testing
You can pressure-test the aluminum-plastic
radiator with a common pump and gage, such as
BT-7002-3 or J-24460-01 with J-23699 (Figure 10).
With the system at a cool temperature, remove the
radiator cap, connect the gage, and apply normal
system operating pressure. Do not exceed 20 psi (138
kPa). Watch the gage needle for an indication of a leak,
and examine the radiator and other cooling system
parts for signs of escaping coolant.
Repair all hose and hose connections as required.
Also check radiator cap to ensure that it will maintain
the correct pressure.
If the radiator is found to be leaking during the
pressure test, mark the leak area so that it is easily
found once the radiator has been removed from the
vehicle.
Off-Vehicle beak Testing
Fig. 9 Aluminum Radiator Drain Cock NOTICE: Do not use boil-out tanks, or vats, or
other tanks that have been used for
couuer and
brass radiators. The flux, acid, and
caustiE cleaners
remaining in these tanks will attack the aluminum
and cause radiator failure. A separate test tank

6B-10 ENGINE COOLING
Fig. 10 Pressure Testing Radiator
containing clean water is strongly recommended
for servicing aluminum-plastic radiator.
I. Install test fittings or rubber test caps in the inlet
and outlet necks and seal the oil cooler fittings
with metal plugs to protect the cooler and keep
the fluid from running out (Fig.
11).
2. Attach pressure tester and gradually apply air
pressure until 20 psi (1
38 kPa) is attained. Do not
exceed 20 psi (138
kPa). Check pressure gage to
see if there is a pressure loss. To ensure that there
are no small leaks, run water over the repair area
and look for bubbles.
(A mild detergent is very
helpful).
If a large water tank is available, the radiator can
be submerged, and a check for air bubbles can be
made.
Fig. I I Aluminum Radiator and Oil Cooler Plugs
Repairable Leaks
There are two types of leaks that can be repaired
on the aluminum-plastic radiator: core leaks and
gasket leaks. Leaks in the plastic tanks cannot be
repaired.
L1_] INLET TANK GASKET
11_] CORE TUBES
OUTLET TANK GASKET
DRAIN COCK GASKET
OIL COOLER GASKETS
JOINT BETWEEN TUBE AND HEADER
Fig. 12 Possible Leak Areas
Repair Methods
There are several methods that can be used to
repair the radiator core, but the hot melt adhesive
method has been found to be the most simple and
effective.
The kit contains adhesive sticks, cotton swabs,
wire brush and primer. The adhesive stick is reusable,
has an indefinite shelf life, and is waste-free. The sticks
must be stored in a sealed container to keep them dry
(Fig. 13).
Fig. 13 Hot Melt Adhesive Repair Kit
Core leaks can occur in a tube, or in the joints special preparation between the tubes and headers. Gasket leaks can occur
in the joints between the plastic tanks and the headers,
cooling Fin Removal or in the joints between the oil cooler fittings and the
tank. Some leaks can be repaired while the radiator is For
damaged areas that are between the cooling
on the car; however, it is usually best to remove the fins,
it may be necessary to remove some of the fins. Do
radiator. not remove more fins
than necessary. Usually
6mm

(1/4") beyond the leak or damage area is enough to
make an effective repair. (Fig. 14).
d""U,"
Fig. 14 Fins Removed from Damaged Area
Tube Blocking
If a tube is severely damaged, it can be blocked
off. (Fig. 15).
NOTICE: DO NOT BLOCK OFF MORE
THAN TWO TUBES IN A RADIATOR.
BLOCKING OFF MORE THAN TWO TUBES
WILL REDUCE THE COOLING
CAPABILITY OF THE SYSTEM.
The tube should be cut off 6mm
(1/4") from the
header and pinched shut before it is cleaned and sealed.
(See General Core Sealing).
CUT
TUBE
Fig. 15 Tube Blocking
Header Repair
If the header or a tube near the header requires
a repair, the side tank does not have to be removed.
A
damp cloth can be placed against the side tank where
the repair has to be made (Fig. 16). The side tank can
also be submerged in a tank of water up to the header
(Fig. 17).
NOTICE: One of these procedures has to be used
when repairs are made on or near the header, to
prevent damage to the tank or gasket.
General Gore Repair
Preparation of the surface in the repair area
cannot be overemphasized. If the leak area surface is
ENGINE COOLING 6B-11
Fig. 16 Using Wet Cloth on Side Tank
not clean, none of the repair materials will stick to the
surface.
1. Position the core so the repair area is accessible.
2. Apply a wet cloth if you are working near the
plastic tanks or the joints between the core tubes
and header (Fig. 16); or submerge the tank in
water (Fig. 17).
SUBMERGE TANK -
Fig. 17 Submerging Side Tank
3. Heat the repair area slightly with a small torch or
heat gun to be sure it is dry.
Do not use a blow
torch.
4. Brush
the area to be repaired with the small steel
brush that is supplied in the kit and blow dust
away from repair area. (See Fig. 18).
5. Open
the tube of primer, using the spurred cap or
a pin, and apply primer to the repair area only.
Use of the primer produces a stronger repair.
Do
not heat the primer.
CAUTION: The primer contains
trichlorethane.
aa It could be harmful, or fatal, if
swallowed. If swaIIowed, gel
medical attention.

88-12 ENGINE COOLING
Fig. 18 Cleaning Area With Steel Brush
e Use with adequate ventilation.
In case of eye contact, flush with
plenty of water and get medical
attention.
In case of body
contact, wash
thoroughly with soap
and water.
Do not
mix the primer with water.
6. Scrub the repair area with a cotton swab until a
fresh swab stays clean. The clear, yellow-brown
coating does not have to be removed (Fig. 19).
Fig. 19 Scrubbing Area with Primer
7. Heat the repair area with the heat gun or by
moving the torch in a circular pattern (Fig. 20).
Use a soft, small blue flame (like a gas stove
flame).
8. Withdraw the torch and rub the adhesive stick on
the repair area (Fig. 21). The adhesive will flow
at a temperature of approximately 500°F (260°C).
If the stick doesn't start to melt, remove it and
reapply the heat.
Do not heat the stick
directly with
a flame. High heat will burn
and
char the adhesive.
9. Continue heating until the adhesive flows and
wets the entire repair area and fills the joint. If a
hole is in the center of a tube, heat the tube and
let the hot surface melt and pull in the adhesive.
The force of the flame or heat gun will also tend
to guide the adhesive toward the hole. For leaks
between a tube and header, flow the adhesive
completely around the tube and header joint with
the tank installed.
Fig. 20 Heating the Repair Area
I
Fig. 21 Applying Hot Melt Adhesive I
10. Heat the repair area until the adhesive is
bubble-free and smooth, with a light yellow color.
Curing is not required.
11. Test the radiator for leaks, when cool. If the
repair area still leaks, reheat it gently to dry it.
Heat and
reflow the adhesive, or apply more as
necessary, to repair the leak.
Tank Gasket beak Repair I 1
Tank gasket leaks can easily be mistaken for tank or
header leaks. If a plastic tank leaks from the header joint
gasket, tighten the clinch tabs with locking-type pliers
(Fig. 22). If this method doesn't seal the leak, remove the
tank for further inspection.
1. Pry open the clinch tabs, except those under inlet,
outlet, and filler necks, using
J33419-A or a screw-
driver (Fig.
23). Lift tabs only enough to allow
removal.
NOTICE: Care should be taken not to overbend
tabs. Overbending could result in breakage. If
there are more than
3 tabs broken on one side of
the header, or more than
2 adjacent tabs together,
the core must be replaced.
2. Lift the tank and slide it out from under the
remaining clinched tab. You may have to tap the

ENGINE COOLING 6B-13
Fig. 22 Tightening Clinch Tabs
Fig.
23 Opening Clinch Tabs
tank with your hand to dislodge the gasket. Lift
the remaining
tab(s) with pliers.
Remove and discard the gasket.
Clean the header and gasket groove of all dirt and
old rubber.
Clean the sealing edge of the plastic tank.
Examine the header gasket surface and tank
flange for evidence of leakage, and clean or repair
the surface to remove dirt, burrs, and bumps.
Remove the oil cooler, if equipped, and install it
in the new tank.
Dip or coat the new
tank gasket in engine coolant
and position it on the header surface. The coolant
helps hold the gasket in place.
Position the tank and gasket to the header, clamp
it in place and secure it by bending four clinch
tabs as shown
in Fig. 24.
Clamp remaining clinch tabs around the header
using the clinching tool or pliers (Fig.
25).
BEND FOUR CLINCH TABS
Fig. 24 Seating Tank to Core
Fig.
25 Clinching Sequence
NOTICE: Tighten the clinch tabs as you would
cylinder head bolts, starting at the center and
working out to the ends.
1 1. Replace the core if there are more than three tabs
broken on one side or two adjacent tabs broken.
12. Install the drain cock, if removed.
13. Test the radiator for leaks.
Oil Cooler Gasket Replacement
The outlet tank must be removed to replace the
oil cooler, but the oil cooler gaskets can be replaced
without removing the tank.
1. Remove the radiator and lay it on a flat surface.
2. Remove the bottom oil cooler nut and loosen the
top nut.
3. Press the oil cooler into the hole and remove the
gasket using a small hook (Fig. 26).
4. Blow-dry all surfaces on the tank and oil cooler.
5. Install a new gasket without lubrication. Be
sure it is seated properly inside the lip of the
fitting.
Reach into the inlet or outlet opening and push
the oil cooler into position against the tank.
Assemble the oil cooler nut loosely.
Replace the other gasket by following the same
procedure.
Install the oil cooler nuts and torque to
20 N.m
(15 lb. ft.). Do not overtighten, as damage to the
gasket could result.
Leak-test the radiator.