1988 PONTIAC FIERO low oil pressure

R-4 AIR CONDITIONING COMPRESSOR OVERHAUL 101-13.
ONE-PIECE SEAL
J-34614 SHAFT SEAL PROTECTOR I G60230-181.8
Fig. 35 Removing and Installing Seal
Place seal protector 9-34614 over end of
compressor shaft and slide new seal onto the
shaft until it stops. Disengage in
NOTICE: HANDLING AND CARE OF SEAL
PROTECTOR IS IMPORTANT. IF SEAL
PROTECTOR IS NICKED OR THE BOTTOM
FLARED, THE NEW SEAL
MAY BE
DAMAGED DURING INSTALLATION.
5. Install the new seal seat retainer ring with its flat
side against the Seal Seat, using Snap-Ring Pliers
5-5403. Use the sleeve from O-Ring Installer
5-3301 1 to press in on the seal seat retainer ring
so that it snaps into its groove.
6. For Leak Test, pressurize suction side
(low-pressure side) of compressor on vehicle with
Refrigerant-12 vapor to equalize pressure to the
drum pressure. Temporarily install the shaft nut
and, with compressor in horizontal position,
rotate the compressor shaft in normal direction
of rotation several times by hand. Leak test the
Seal and correct any leak found. Remove, discard
and later replace the shaft nut.
7. Remove any excess oil, resulting from installing
the new seal parts, from the shaft and inside the
compressor neck.
8. Install the Clutch Plate and Hub assembly as
described in minor repair procedures.
9. Reinstall compressor belt and tighten bracketry.
10. Evacuate and Charge the Refrigerant System
according to directions in Section
1B.
Off-Car
Install or
Connect
1. Follow applicable on-car procedures.
2. To Leak Test, install leak Test Fixture 5-9625 on
rear head of compressor and connect gage
charging lines, or pressurize suction side (low
pressure side) of compressor on car with
Refrigerant-12 vapor to equalize pressure to the
drum pressure. Temporarily install the shaft nut and,
with compressor in horizontal position and
using a wrench, rotate the compressor shaft in
normal direction of rotation several times by
hand.
Leak test the seal and correct any leak
found. Remove, discard and later replace with a
new shaft nut.
PRESSURE RELIEF VALVE
Fig. 4 1
The Pressure Relief Valve, located in the
compressor rear head casting, should only be replaced
after purging the system of refrigerant,
A new valve
and O-ring coated with 525 viscosity refrigerant oil
should be installed.
HIGH PRESSURE CUT-OFF SWITCH
Fig. 42
Remove or Disconnect
1. Discharge A/C system
2. Electrical connector at switch
3. Switch retaining ring using
J-5403-A internal
snap ring pliers.
4. Switch from compressor by pulling on terminal
housing.
5. Old O-ring seal from switch cavity using
J-9553-01 O-ring removal tool or equivalent.
If high pressure cut-off switch will be reinstalled.
in compressor, a new O-ring seal must be
used
and preferably a new retainer ring should also be
used. A new switch kit has the O-ring and
retainer ring included.
install or Connect
1.
Check switch cavity and O-ring groove in the rear
head for dirt or foreign material and clean as
necessary. Install new O-ring coated with cleall
525 viscosity refrigerant oil into groove in switch
cavity.
2. Lubricate the high pressure cut-off
switgh
housing with clean 525 viscosity refrigerant

R-4 818 CONDITIONING COMPRESSOR OVERHAUL 1D1-19
retainers are to be removed, remove two sets and
then rotate compressor and Holding Fixture
J-25008-A in vise for access to the remaining two
valve plates and retainers.
Install or Connect
1. Install Discharge Valve Plates and/or Retainers.
Reposition compressor and Holding Fixture in
vise as necessary for access.
Valve plates must
be tight
following retainer assembly.
2. Reinstall compressor Shell as described in
SHELL AND O-RINGS replacement
procedures.
3. Evacuate and charge the refrigerant system
according to the directions in Section
1B.
CYLINDER AND SHAFT ASSSEMBLY
Remove or Disconnect
Discharge the refrigerant system according to the
directions in Section
1B.
Remove the Clutch Plate and Hub assembly as
described in CLUTCH PLATE AND HUB
removal procedure.
Perform Steps
1 through 4 of CLUTCH ROTOR
AND BEARING removal procedure but do not
loosen or remove the pulley rim mounting screws.
Remove the Clutch Rotor and Bearing, Clutch
Coil and Pulley Rim as an assembly. Be careful
not to drop the Puller Guide J-25031, when
removing the assembly.
Remove the shaft seal as described in SHAFT
SEAL removal procedure.
Remove the front head as described in FRONT
HEAD REMOVAL procedure.
Remove the thrust and belleville washers as
described in THRUST AND BELLEVILLE
WASHERS removal procedures.
Remove the compressor shell as described in
SHELL removal procedure.
Remove the discharge valve plate and retainer as
described in DISCHARGE VALVE PLATE
AND RETAINER removal procedure.
Remove the high pressure relief valve as
described in
HIGH PRESSURE RELIEF
VALVE REMOVAL PROCEDURE.
L
Install or Connect
1. Replace above parts in opposite order.
2. Evacuate and charge the refrigerant system
according to the directions in Section
1B.
LEAK TESVING (EXTERNAL AND INTERNAL)
Bench-Check Procedure
1. Install Test Plate J-9625-A on Rear Head of
compressor.
2. Attach center hose of Manifold Gage Set on
Charging Station to a refrigerant drum standing
in an upright position and open valve on drum.
3. Connect Charging Station high and low pressure
lines to corresponding fittings on Test Plate J-9625-A, using
5-5420 Gage
Adapters if hoses
are not equipped with valve depressors.
Suction port (low-side) of compressor has
large internal opening. Discharge port
(hi-side) has smaller internal opening into
compressor.
Open low-pressure control, high-pressure control
and refrigerant control on Charging Station to
allow refrigerant vapor to flow into compressor.
Using a Leak Detector, check for leaks at
Pressure Relief Valve, compressor shell to
cylinder, compressor front head seal, and
compressor Shaft Seal. After checking, shut off
low pressure control and high pressure control on
Charging Station.
If an external leak is present, perform the
necessary corrective measures and recheck for
leaks to make certain the leak has been corrected.
Loosen the Manifold Gage hose connections to
the Gage Adapters J-5420 connected to the low
and high sides and allow the vapor pressure to
release from the compressor.
Disconnect both Gage Adapters
5-5420 from the
Test Plate J-9625-A.
Rotate the complete compressor assembly (not
the crankshaft or drive plate hub) slowly several
turns to distribute oil to all cylinder and piston
areas.
Install a shaft nut on the compressor crankshaft
if the drive plate and clutch assembly are not
installed.
Using a box-end wrench or socket and handle,
rotate the compressor crankshaft or clutch drive
plate on the crankshaft several turns to ensure
piston assembly to cylinder wall lubrication.
Connect the Charging Station high pressure line
or a high pressure gage and Gage Adapter J-5420
to the Test Plate J-9625-A high side connector.
Attach an Adapter
9-5420 to the suction or low
pressure port of the Test Plate
J-9625-19 to open
the Schrader-type valve.
Oil will drain out of the compressor suction port
adapter if the compressor is positioned with the
suction port downward.
Attach the compressor to the Holding Fixture
J-25008-A using metric mounting screws. Clamp
the compressor Holding Fixture in a vise so that
the compressor can be manually turned with a
wrench.
Using a wrench, rotate the compressor crankshaft
or drive plate hub ten complete revolutions at a
speed of approximately one-revolution per
second.
Turning the compressor at less than
one-revolution per second can result in a lower
pump-up pressure and disqualify a good pumping
compressor.
Observe the reading on HIGH pressure gage at
the completion of the tenth revolution of the
compressor. The pressure reading for a good
pumping compressor should be 344.75
kPa (50 p.
s.i.) or above. A pressure reading of less than 3 10.
275 kPa (45 p.s.i.) would indicate one or more

101.20 R-4 AIR CONDITIONING COMPRESSOR OVERHAUL
suction and/or discharge valves leaking, an
internal leak or an inoperative valve, and the
compressor should be disassembled and checked
for cause of leak. Repair as needed, reassemble
and repeat the pump-up test. Externally leak test.
When the pressure pump-up test is completed,
release the air pressure from the HIGH side and
remove the Gage Adapters J-5420 and Test Plate
J-9625-A. 18. On the R-4 compressor, tilt the compressor so
that the compressor suction and discharge ports
are down. Drain the oil from the compressor.
19. Allow the compressor to drain for
10 minutes,
then charge with the proper amount of oil. The
oil may be poured into the suction port.
If further assembly or processing is required, a
shipping plate or Test Plate J-9625-A should be
installed to keep out air, dirt and moisture until
the compressor is installed.

2B-2 BUMPERS
REAR BUMPER FASCIA
Removal
Place a jack stand under fascia before removing
bolts to prevent it from dropping down when fascia
attaching bolts are removed. Fascia will pivot on the
opposite end when one end is disconnected. Do not
rotate energy absorber any more than necessary to
align mounting holes.
1. Remove fascia attaching bolts and fascia to
fender attaching screws on right and left side, and
remove fascia and spacers.
2. If energy absorber is to be replaced, remove the
bolts and nuts from the front of the unit and the
nut from the stud at the rear. The stud at the rear
of the absorber is attached to a bracket in the
frame. Remove the bolt holding this bracket in
the frame to remove the absorber.
Installation
1. Install energy absorber if removed.
2. Support fascia during installation to prevent
rotation of energy absorbers.
3. Install spacers and bolts at fascia to energy
absorber brackets.
4. Install fascia to fender attaching screws.
5. Check for proper clearance.
6. If adjustment is required to align the fascia, use
shims as necessary. Vertical and lateral
adjustment can be made at slots in fascia and
absorber brackets. Torque all bolts and nuts. (See
Specifications.)
FRONT BUMPER
Removal
1. Remove
front end fascia as shown in Section 2C.
2. Remove bumper barlenergy absorber assembly
from body.
3. If energy absorber must be replaced, drill out pop
rivets, and install new absorber with nuts, bolts,
and locking washers.
4. To install, reverse above procedure.
REAR BUMPER
Removal
1. Remove left hand rear quarter trim panel.
2. Remove right hand rear quataer trim panel.
3. Remove spare tire assembly.
4. Remove rear center trim panel.
5. Remove right tail light assembly.
6. Remove left tail light assembly.
7. Remove tail light center piece.
8. Remove bumper cover lower retainers.
9. Remove right-side bumper cover fasteners from
inside of compartment.
10. Remove left side bumper cover fasteners from
inside of compartment.
11. Remove bumper cover upper retainers.
12. Remove cover.
13. To dissasemble impact bar, proceed as follows:
a. Remove bolts attataching impact bar to
rear end panel.
b. Remove rivets retaining pad to impact
bar.
14. To install, reverse above procedure.
BUMPER ENERGY ABSORBING UNITS
The absorbing capability for both front and rear
bumper systems is achieved through two energy
absorbing devices in each bumper. These units convert
the energy of an impact into heat and restoration. The
energy absorbing device consists of two main
subassemblies: the piston tube assembly and the
cylinder tube assembly. The piston tube assembly is
filled with an inert gas under pressure and consists of
a bumper bracket, piston tube, orifice, seal, piston seal,
piston, and stop-ring. The cylinder tube assembly is
filled with a hydraulic fluid and consists of a frame
bracket, cylinder tube, mounting stud, and metering
pin.
Upon impact, as the energy absorber is collapsed,
the hydraulic fluid in the cylinder tube is forced into
the piston tube through the orifice. The metering pin
controls the rate at which this fluid passes from the
cylinder tube through the orifice and into the piston
tube. This controlled passage of fluid provides the
energy absorbing action.
The hydraulic fluid that is forced from the
cylinder tube into the piston tube displaces the floating
piston, compressing the gas behind the floating piston.
After impact, the pressure of the compressed gas
behind the floating piston forces the hydraulic fluid
back into the cylinder tube assembly, extending the
unit to its normal position.
Some front and rear bumpers (J and
F Models)
use a plastic honeycomb pad energy absorber (except
J wagon rear bumper). This energy absorber will
compress on impact, and both the energy absorber and
the urethane fascia will return to their original shape.
The energy absorber pad has no moving parts.
The J wagon rear bumper system uses a hydraulic
energy absorbing unit, more commonly known as a
"minisorber".
TESTING FRONT OR REAR ENERGY
ABSORBER OPERATION
The right and left energy absorbing devices are to
be diagnosed separately. The following checks are to be
made on each unit:
1. Leakage
Some oil wetting may be visible due to the grease
packed in the crimp recess. Therefore, a stain or trace
of oil on the piston tube near the crimp is normal.
However, if oil is dripping continuously from the crimp
or the stud end of the unit, a leak is indicated and the
unit should be replaced.

3D-8 REAR SUSPENSION
TYPICAL BUMPER INSTALLATION
1-LONGITUDINAL REINFORCEMENT
2-WELD NUTS
3-27NM (20
FT.LB.1
4-AXLE ASM.
5-JOUNCE STOP REINF.
Fig. 6 1 1 Rubber Bumper Assembly
Leakage Diagnosis
The appearance of oil film on the shock absorber body or
piston rod
is normal. Any dripping of oil is unacceptable.
I OIL FILM OK I
ANY OIL DROP
IS UNACCEPTABLE
I Disposal I Due to the high pressure of gas it is advised that, upon
scraping or disposal of these shock absorbers, the pres-
sure be released. This
is carried out as follows:
a. Clamp shock in vise with piston rod pointing down.
b. Measure approx. 10-15 mm (0.5 in.) from bottom of
shock and drill an approx. 5
mm hole so the gas can
escape.
c. Measure approx. 140-150
mm (5.5-6.0 in.) from first hole
and drill an approx. 5
mm hole to facilitate drainage of
oil.
d. Drain oil'from shock and then dispose of shock.
BOTTOM
DRILL THlS HOLE FIRST
140-150 rnrn (5.5-6.0 in.)
DRILL THlS HOLE LAST
DUE TO EXPLOSION
UNDER
HIGH DO NOT APPLY
HEAT OR FIRE
Fig. 612 Gas Shock

TIRES AND WHEELS 3E-9
Another method is to dismount the tire and
rotate it 180 degrees on the rim. It is important that
this be done on tire and wheel assemblies which are
known to be causing a vibration as it is just as likely to
cause good assemblies to vibrate.
Refer to Section 3, "Vibration Diagnosis" for
more details.
ALUMINUM WHEEL CLEANING
Aluminum wheels should be cleaned and waxed
regularly. Do not use abrasive cleaners, as they could
damage the protective coating.
ALUMINUM WHEEL HUB CAP
Remove or Disconnect
1. Tire and wheel assembly
2. Place a block of wood approximately 2" in
diameter with a squared off end against the back
surface of the cap.
A sharp hammer biow on the
block of wood will
remove the cap.
Install or Connect
1. Place
cap into position at wheel opening and
place a block of wood at least three inches in
diameter against cap face. Install cap by striking
block of wood with hammer.
2. Tire and wheel assembly
NOTICE: Failure to hit cap squarely without the
load distributed evenly could result in permanent
damage to the cap.
ALUMINUM WHEEL POROSITY REPAIR
1. Remove tire and wheel assembly.
2. Locate
leaking areas by inflating tire to 345
kPa
(50 psi) and dipping tire and wheel assembly into
a water bath.
3. Mark
leak areas and remove tire from wheel.
4. Scuff inside surface at leak area with 80 grit
sandpaper and clean area with general purpose
cleaner such as
3M #08984 or equivalent.
5. Apply 1/8" thick layer of adhesive/sealant P/N
1052366 or equivalent to leak area and allow
twelve hours of drying time.
6. Mount tire on wheel, pressurize to 345 kPa (50
psi) and check for leaks.
CAUTION: To avoid serious personal
injury, do not stand over tire when
inflating. Bead may break when bead
snaps over safety hump. Do not
exceed
275 kPa (40 psi) pressure
when inflating any tire if beads are
not seated.
14 275 kPa (40 psi)
pressure will not seat beads, deflate,
relubricate the beads and reinflate.
Overinflation may cause the bead to
break and cause serious personal
injury.
7. Adjust
tire pressure to meet specifications.
8. Balance tire and wheel assembly.
9. Install tire and wheel assembly.
ALUMINUM WHEEL REFINISHING
A protective clear or color coating is applied to
the surface of original equipment cast aluminum
wheels.
A surface degradation condition can begin to
develop if frequent, repeated automatic car wash
cleaning abrades or wears off the factory applied
protective coating. This can happen at some automatic
car wash facilities using aggressive silicon carbide
tipped tire brushes
to clean white walls and tires. Once
the protective coating is
damaged, exposure to caustic
cleaners and/or road salt further causes surface
degradation. The following procedure details how to
strip, clean
and recoat aluminum wheels that are
affected by these conditions.
Required Materials:
A~nchern Alumi Prep #33 - stock
#DX533 or equivalent - cleaning and
conditioning chemical for aluminum.
Amchem Alodine
# 1001 - stock #DXSOT
or equivalent - coating chemical for
aluminum.
Ditzler Delclear Acrylic Urethane Clear
-
stock #DAU-75 or equivalent.
Ditzler Delthane Ultra-Urethane Additive
- stock DXR-80 or equivalent.
Service Procedure:
1. Mark wheel and wheel stud for position on car.
2. Remove tire and wheel assembly from car.
3. Mark location of outboard weights and remove.
4. Wash wheel inside and out with water base all
purpose cleaner. Remove grease and oil with
solvent cleaner.
5. Mask off tire prior to painting.
6. Select and follow the correct procedure,
"Aluminum Damage on Wheel Surface" or
"Clear Coat Damage on Unpainted Wheels".
7. Replace wheel weights with nylon coated
weights.
8. Install tire and wheel assembly on car and tighten
wheel nuts to proper torque.
Accent Color Preparation
1. Sand over painted areas that will not require
recoloring with 400 grit (wet or dry) to promote
adhesion of clear coat.
Aluminum Damage on Wheel Surface
1. Mount tire and wheel on brake lathe and spin
slowly.
2. Sand wheel with backing block or pad by holding
abrasive flat to surface of wheel and moving
slowly back and forth from center to outer edge
to remove damage. Use the following sandpaper
grits in the order listed.
A. Sand with 80 grit
B. Sand with 150 grit
C. Sand with 240 grit
3. Continue with "Recoating Procedure."

REAR AXLE 48-13
2. Drive
pinion oil seal from carrier and remove
front pinion bearing. If the bearing is to be
replaced, remove outer race from carrier.
3. If rear pinion bearing is to be replaced remove
outer race from carrier using a punch in slots
provided for this purpose.
1 -REMOVER J-22912-01 7%" OR J-33868
2-OPENING IN TOOL MUST BE SUPPORTED
Fig.
604 Removing Rear Pinion Bearing
Cleaning and Inspecting
1. Clean
all rear axle bearings thoroughly in clean
solvent (do not use a brush). Examine bearings
visually and by feel. All bearings should feel
smooth when oiled and rotated while applying as
much hand pressure as possible. Minute scratches
and pits that appear on rollers and races at low
mileage are due to the initial pre-load, and
bearings having these marks should not be
rejected.
2. Examine sealing surface of pinion flange for nicks
burrs, or rough tool marks which would cause
damage to the seal and result in an oil leak.
Replace if damaged.
'
3. Examine carrier bore and remove any burrs that
might cause leaks around the O.D. of the pinion
seal.
4. Examine the ring gear and drive pinion teeth for
excessive wear and scoring. If any of these
conditions exist replacement of the gear set will
bs required.
5. Inspect the pinion gear shaft for unusual wear;
also check the pinion and side gears and thrust
washers.
6. Check the press fit of the side bearing inner race
on the rear axle case hub by prying against the
shoulder at the puller recess in the case. Side
bearings must be a tight press fit on the hub.
7. Diagnosis of a rear axle failure such as: chipped
bearings, loose (lapped-in) bearings, chipped
gears, etc., is a warning that some foreign
material is present; therefore the axle housing
must be cleaned.
Drive Pinion
Assemble
I. If a new rear pinion bearing is to be installed,
install new outer race.
2. If a new front pinion bearing is to be installed,
install new outer race.
Fig. 605 Installing Rear Pinion Bearing Outer Race
1- J-8092 DRIVE H-,.wb- 6
Fig. 606 Installing Front Pinion Bearing Outer Race
Setting Drive Pinion Depth
Pinion depth is set with pinion setting gage
J 21777-B. The pinion setting gage provides in effect a
"Nominal" or "Zero" pinion as a gaging reference.
Set up pinion setting gage as follows:
1. Make certain all gage parts are clean.
2. Lubricate front and rear pinion bearings which
will be used in final reassembly and position them
in their respective races in the carrier. Bearings
used with gage set must be those to be installed
in vehicle, in order to insure accurate reading.
3. Assemble pinion setting gage assembly into
carrier housing as follows:
Step 1
Figure 607
a.
Install Pinion Bearing Pre-Load Stud J
21777-43 through Pilot J 23597-12 and into
Gage Plate
J 23597- 11.
b. Install stud and plate assembly into housing
and install Front Pinion Bearing Pilot
J
21777-42 and hex nut over end of stud,
tightening nut until snug and rotate gage

BRAKES 5-3
DIAGNOSIS AND INSPECTION
BRAKE SYSTEM TESTING
(Figures
2 through 4)
Brakes should be tested on dry, clean, reasonably
smooth and level roadway. A true test of brake performance
cannot be made if the roadway is wet, greasy or covered
with loose dirt so that all tires do not grip the road equally.
Testing will also be affected if the roadway is crowned
which would throw the weight of the car toward the wheels
on one side. If the roadway is too rough, the wheels will tend
to bounce. Test brakes at different car speeds with both light and
heavy pedal pressure, avoid locking the brakes and sliding
the tires. Locked brakes and sliding tires do not indicate
brake efficiency, because heavily braked, but turning
wheels will stop the car in less distance than locked brakes.
More tire-to-road friction is present with a heavily braked
turning tire than with a sliding tire. The brake system is designed and balanced to avoid
locking the wheels, except at very high deceleration levels.
The shortest stopping distance and best control is achieved
without brake lock-up.
Because of high deceleration capability, a firmer pedal
may be felt at higher deceleration levels.
External Conditions That Affect Brake Performance
1. Tires. Tires having unequal contact and grip on road
will cause unequal braking. Tires must be equally
inflated and tread pattern of right and left tires must
be approximately equal.
2. Car Loading. A heavily loaded car requires more
braking effort. When a car has unequal loading, the
most heavily loaded wheels require more braking
power than others.
3. Wheel Alignment. Misalignment of the wheels, par-
ticularly excessive camber and caster, will cause the
brakes to pull to one side.
4. Front Wheel Bearings. A loose front wheel bearing
BRAKE FLUID LEAKS
With engine running at idle and the transmission in neu-
tral, depress the brake pedal and hold a constant foot pres-
sure.
If the pedal gradually falls away with the constant
pressure, the hydraulic system may be leaking. Perform a
visual check to confirm any suspected leak.
Check the master cylinder fluid levels. While a slight drop
in reservoir level does result from normal lining wear, an
abnormally low level in either reservoir indicates
a leak in
the system. The hydraulic system may be leaking either
internally or externally. See "Master Cylinder Check."
Also, the system may appear to pass this test but still have
slight leakage.
If fluid levels are normal, check the vacuum booster
pushrod length. If an incorrect length pushrod is found,
adjust or replace the
pushrod. Check the service brake
pedal travel and the parking brake adjustment.
When checking the fluid levels, the master cylinder reser-
voir may be as low as
25 mm (1 inch) from the top if the front
linings are worn. This is not abnormal.
MASTER CYLINDER CHECK
These checks will help locate some master cylinder mal-
functions. Use the Brake Diagnosis Charts to help isolate
the problem if it is not found by using these tests.
1. Check for a cracked master cylinder casting or brake
fluid around the master cylinder. Leaks are indicated
only if there is at least a drop of fluid. A damp condi-
tion is not abnormal.
2. Check for a binding pedal linkage.
3. Disassemble the master cylinder and check for swol-
len or stretched piston
seal(s). If swollen seals are
found, substandard or contaminated brake fluid
should be suspected.
If contaminated, all compo-
nents should be disassembled and cleaned. All rub-
ber components should be replaced and all the pipes
should be flushed.
permits the front wheel to tilt and lose contact with the
SUBSTANDARD OR CONTAMINATED brake shoe linings causing erratic brake operation. BRAKE FLUID
WARNING LAMP OPERATION
The brake system uses a single red "BRAKE" warning
lamp located in the instrument panel cluster. When the
ignition switch is in the "START" position, the "BRAKE"
warning lamp should come on. It should go off when the
ignition switch returns to the "RUN" position.
The following conditions will activate the "BRAKE"
warning lamp:
1. Parking brake applied. The lamp should be on when
tfie parking brake is applied and the ignition switch is
"ON."
2. Pressure differential switch detects a failure. See
"Brake Pressure Differential Warning Switch" in this
section. Improper
brake fluid, mineral oil or water in the fluid may
cause the brake fluid to boil or the rubber components to
deteriorate.
If piston cups are swollen, the rubber parts have dete-
riorated. This deterioration may also be seen by swollen
wheel cylinder piston cups on the drum brake wheels or a
swollen master cylinder cover diaphragm.
If rubber deterioration is evident, disassemble all hydrau-
lic parts and wash with alcohol. Dry these parts with com-
pressed air before assembly to keep alcohol out of the
system. Replace all rubber parts in the system, including
hoses. Check for fluid on the linings. If excessive fluid is
found, replace the linings.
If master cylinder piston seals are satisfactory, check for
leakage or excessive heat conditions. If condition is not
found, drain fluid, flush with brake fluid, fill and bleed the
system.