boot CHEVROLET DYNASTY 1993 Owner's Guide

(5) Clamp caliper in vise (with protective caps on
vise jaws). (6) Remove dust boot from the brake caliper and
discard (Fig. 1).
(7) Using a plastic trim stick, work piston seal out of
its groove in caliper piston bore (Fig. 2). Discard old
seal. Do not use a screwdriver or other metal tool
for this operation, because of the possibility of
scratching piston bore or burring edges of seal
groove. The double pin caliper uses a sealed for life bushing
and sleeve assembly. If required this assembly can be
serviced using the following procedure. (1) Push out and then pull the inner sleeve from
inside of the bushing using your fingers as shown in
(Fig. 3)
(2) Using your fingers collapse one side of the bush-
ing. Then pull on the opposite side to remove the
bushing from the brake caliper assembly (Fig. 4).
CLEANING AND INSPECTION OF BRAKE CALIPER
Clean all parts using alcohol or a suitable solvent
and wipe dry using only a lint free cloth, no lint
residue can remain in caliper bore. Clean out all drilled
passages and bores. (Whenever a caliper has been
disassembled, a new boot and seal must be in-
stalled at assembly). Inspect the piston bore for scoring or pitting. Bores
that show light scratches or corrosion, can usually be
cleared of the light scratches or corrosion using crocus
cloth. Bores that have deep scratches or scoring should be
honed. Use Caliper Hone, Special Tool C-4095, or
equivalent providing the diameter of the bore is not
increased more than 0.0254 mm (0.001 inch) (Fig. 5). If the bore does not clean up within this specification,
a new caliper housing should be installed. Install a new
piston if the old one is pitted or scored. When using Caliper Honing Tool, Special Tool
C-4095, coat the stones and bore with brake fluid.
After honing the bore, carefully clean the seal
and boot grooves with a stiff non-metallic rotary
brush.
Fig. 1 Removing Piston Dust Boot
Fig. 2 Removing Piston Seal
Fig. 3 Removing Inner Sleeve
Ä BRAKES 5 - 41

Use extreme care in cleaning the caliper after
honing. Remove all dirt and grit by flushing the
caliper with brake fluid; wipe dry with a clean,
lint free cloth and then clean a second time.
ASSEMBLING DISC BRAKE CALIPER
Clamp caliper in vise (with protective caps on vise
jaws).
CAUTION: Excessive vise pressure will cause bore
distortion and binding of piston. Dip new piston seal in clean brake fluid and install
in the groove of the caliper bore. Seal should be po-
sitioned at one area in groove and gently worked
around the groove (Fig. 1), using only your fingers
until properly seated. NEVER USE AN OLD PISTON SEAL. (Be sure
that fingers are clean and seal is not twisted or
rolled) (Fig. 1).
Coat new piston boot with clean brake fluid leav-
ing a generous amount inside boot. Position dust boot over piston after coating with
brake fluid. Install piston into caliper bore pushing it past the
piston seal until it bottoms in the caliper bore (Fig.
2).
CAUTION: Force must be applied to the piston uni-
formly to avoid cocking and binding of the piston in
the bore of the caliper.
Fig. 1 Installing New Piston Seal
Fig. 2 Pushing Piston into Bore
Fig. 4 Removing Bushings From Caliper
Fig. 5 Honing Piston Bore
5 - 42 BRAKES Ä

Position dust boot in counterbore of the caliper piston
bore. Using a hammer and Installer Piston Caliper Boot,
Special Tool C-4689 and Handle, Special Tool C-4171,
drive boot into counterbore of the caliper (Fig. 3).
Use the following steps, to install the Guide Pin
Sleeve Bushings into the caliper assembly. (1) Fold the bushing in half lengthwise at the solid
middle section of the bushing (Fig. 4).
(2) Using your fingers insert the folded bushing into
the caliper assembly (Fig. 5). Do not use a sharp
object to perform this step do to possible damage
to the bushing. (3) Unfold the bushing using your fingers or a
wooden dowel until the bushing is fully seated into the caliper assembly. Flanges should be seated
evenly on both sides of the bushing hole in the cali-
per assembly (Fig. 6).
Install the Guide Pin Sleeve into the guide bushing
using the following procedure. (1) Install the sleeve into one end of the bushing
until the seal area of the bushing is past the seal
groove in the sleeve (Fig. 7). (2) Holding the convoluted end of the bushing with
one hand. Push the sleeve through the bushing (Fig.
Fig. 5 Installing Caliper Guide Pin Sleeve Bushings
Fig. 6 Bushing Correctly Installed In Caliper
Fig. 3 Installing Dust Boot in Caliper Counterbore
Fig. 4 Folded Caliper Guide Pin Bushing
Ä BRAKES 5 - 43

removal will be necessary. Remove the shoe and lin-
ing assemblies (see Brake Shoe Removal).Combined shoe and lining thickness should be
measured at the thinnest part of the assembly. When a shoe and lining assembly is worn to a
thickness of approximately 7.0 mm (9/32 inch) it
should be replaced. Replace both shoe assemblies (inboard and out-
board) on both wheels whenever shoe assemblies on
either side are replaced. If a shoe assembly does not require replacement.
Reinstall it, making sure each shoe assembly is re-
turned to its original position on the wheel of the ve-
hicle from which it was removed. (See Brake Shoe
Installation).
SERVICE PRECAUTIONS
WARNING: DUST AND DIRT ON BRAKE PARTS
GENERATED DURING THE NORMAL USE AND
WEAR OF MOTOR VEHICLE BRAKE SYSTEMS CAN
CONTAIN ASBESTOS FIBERS. BREATHING EXCES-
SIVE CONCENTRATIONS OF ASBESTOS FIBERS
CAN CAUSE SERIOUS BODILY HARM, SUCH AS
ASBESTOSIS AND CANCER. EXTREME CARE
SHOULD BE EXERCISED WHILE SERVICING
BRAKE ASSEMBLIES OR COMPONENTS. DO NOT CLEAN BRAKE ASSEMBLIES OR COM-
PONENTS WITH COMPRESSED AIR OR BY DRY
BRUSHING; USE A VACUUM CLEANER SPECIFI-
CALLY RECOMMENDED FOR USE WITH ASBES-
TOS FIBERS. IF A SUITABLE VACUUM CLEANER IS
NOT AVAILABLE, CLEANING SHOULD BE DONE
WET USING A WATER DAMPENED CLOTH. DO NOT CREATE DUST BY SANDING, GRINDIN-
G,AND/OR SHAVING BRAKE LININGS OR PADS
UNLESS SUCH OPERATION IS DONE WHILE USING
PROPERLY EXHAUST VENTILATED EQUIPMENT. DISPOSE OF ALL DUST AND DIRT SUSPECTED
TO CONTAIN ANY ASBESTOS FIBERS IN SEALED
BAGS OR CONTAINERS TO MINIMIZE DUST EXPO-
SURE TO YOURSELF AND OTHERS. FOLLOW ALL RECOMMENDED PRACTICES PRE-
SCRIBED BY THE OCCUPATIONAL SAFETY AND
HEALTH ADMINISTRATION AND THE ENVIRON-
MENTAL PROTECTION AGENCY. FOR THE HAN-
DLING, PROCESSING, AND DISPOSITION OF DUST
OR DIRT WHICH MAY CONTAIN ASBESTOS FI-
BERS. IT IS RECOMMENDED NOT TO BREATH ANY
TYPE OF BRAKE LINING MATERIAL DUST EVEN
ASBESTOS FREE, DUE TO THE FIBROUS NATURE
OF THE MATERIALS BEING USED.
Grease or any other foreign material must be kept
off the caliper assembly, surfaces of the braking disc
and external surfaces of the hub, during service pro-
cedures. Handling the braking disc and caliper should be done
in such a way as to avoid deformation of the disc and
scratching or nicking the brake linings (pads). During removal and installation of a wheel and tire
assembly, use care not to strike the caliper. Before vehicle is moved after any brake service
work, be sure to obtain a firm brake pedal.
BRAKE SHOE REMOVAL
(1) Raise vehicle on jackstands or centered on a
hoist. (2) Remove rear wheel and tire assemblies.
(3) Remove caliper attaching bolts (Fig. 2).
(4) Lift caliper away from adapter rails (Fig. 3).
(5) Remove outboard shoe. By prying the shoe re-
taining clip over the raised area on the caliper. Then
slide the shoe down and off the caliper (Fig. 4). (6) Pull inboard shoe away from piston, until the
retaining clip is free from the cavity in the piston. (Fig.
5).
CLEANING AND INSPECTION
Check for piston seal leaks (brake fluid in and
around boot area and inboard lining) and for any
ruptures of piston dust boot. If the boot is damaged, or
fluid leak is visible, disassemble caliper assembly and
install a new seal and boot (and piston if scored). Refer
to procedure titled Disc Brake Caliper Disassembly.
BRAKE SHOE INSTALLATION
(1) Retract piston.
If the originally removed brake shoe assem-
blies are to be replaced back on vehicle. Be sure
Fig. 2 Removing Caliper Attaching Bolts
5 - 46 BRAKES Ä

DISASSEMBLING REAR CALIPER ASSEMBLY
CLEANING AND INSPECTION
Check for piston fluid seal leaks (brake fluid in and
around boot area and inboard lining) and for any
ruptures of piston dust boot. If boot is damaged, or
fluid leak is visible, disassemble caliper assembly
and install a new seal and boot,(and piston if scored).
Refer to procedures titled Disc Brake Caliper Disas-
sembly. Check the caliper dust boot and caliper pin bush-
ings to determine if they are in good condition. Re- place if they are damaged, dry, or found to be brittle.
Refer to Cleaning And Inspection Of Brake Caliper. (1) Remove caliper from braking disc (See Brake
Shoe Removal). Hang assembly on a wire hook away
from braking disc, so hydraulic fluid cannot get on
braking disc (See Fig. 4 in Brake Shoe Removal). Place
a small piece of wood between the piston and caliper
fingers. (2) Carefully depress brake pedal to hydraulically
push piston out of bore. (Brake pedal will fall away
when piston has passed bore opening.) Then prop up
the brake pedal to any position below the first inch of
pedal travel, this will prevent loss of brake fluid from
the master cylinder. (3) If both front caliper pistons are to be removed,
disconnect flexible brake line at frame bracket after
removing piston. Plug brake tube and remove piston
from opposite caliper. Using the same process as above
for the first piston removal.
WARNING: UNDER NO CONDITION SHOULD AIR
PRESSURE BE USED TO REMOVE PISTON FROM
CALIPER BORE. PERSONAL INJURY COULD RE-
SULT FROM SUCH A PRACTICE.
(4) Disconnect brake flexible hose from the caliper.
To disassemble, mount caliper assembly in a vise
equipped with protective jaws.
CAUTION: Excessive vise pressure will cause bore
distortion and binding of piston.
Support rear caliper assembly in a vise. Then remove
caliper to piston dust boot and discard (Fig. 1).
Using a plastic trim stick, work piston seal out of its
groove in caliper piston bore (Fig. 2). Discard old seal.
Do not use a screwdriver or other metal
Fig. 7 Installing Caliper
Fig. 8 Installing Attaching Bolts
Fig. 1 Removing Piston Dust Boot
5 - 48 BRAKES Ä

tool for this operation, because of the possibility
of scratching piston bore or burring edges of seal
groove. The double pin caliper uses a sealed for life bushing
and sleeve assembly. If required this assembly can be
serviced using the following procedure. (1) Using your fingers push on one end the inner
sleeve until it pops out of the bushing. Then grasp the
inner sleeve with your fingers and pull the inner sleeve
out from the inside of the bushing (Fig. 3). (2) Using your fingers collapse one side of the bush-
ing. Then pull on the opposite side to remove the
bushing from the caliper assembly (Fig. 4).
CLEANING AND INSPECTION
Clean all parts using alcohol or a suitable solvent
and wipe dry. Clean out all drilled passages and bores
on the caliper assembly body. (Whenever a caliper
has been disassembled, a new boot and seal must
be installed at assembly). Inspect the caliper assembly piston bore for scoring
or pitting. Bores that show light scratches or corrosion,
can usually have the scratches or corrosion removed
using crocus cloth. Bores that have deep scratches or scoring should be
honed. Use Caliper Hone, Special Tool C-4095, or
equivalent providing the diameter of the bore is not
increased more than 0.0254 mm (0.001 inch) (Fig. 5). If the bore does not clean up within this specification,
a new caliper housing should be installed. Install a new
piston if the old one is pitted or scored. When using Caliper Honing Tool, Special Tool
C-4095, coat the stones and bore with brake fluid.
After honing the bore, carefully clean the seal
and boot grooves with a stiff non-metallic rotary
brush. Use extreme care in cleaning the caliper after
honing. Remove all dirt and grit by flushing the
caliper with brake fluid; wipe dry with a clean,
lint free cloth and then clean a second time.
ASSEMBLING REAR DISC BRAKE CALIPER
Clamp caliper in vise (with protective caps on vise
jaws).
Fig. 2 Removing Piston Seal
Fig. 3 Removing Inner Sleeve From Bushing
Fig. 4 Removing Bushings From Caliper
Ä BRAKES 5 - 49

CAUTION: Excessive vise pressure will cause bore
distortion and binding of piston. Dip new piston seal in clean brake fluid and install
in the groove of the caliper bore. Seal should be po-
sitioned at one area in groove and gently worked
around the groove (Fig. 6), using only your fingers
until properly seated. NEVER USE AN OLD PISTON SEAL. (Be sure
that fingers are clean and seal is not twisted or
rolled) (Fig. 6).
Coat new piston boot with clean brake fluid leav-
ing a generous amount inside boot. Position dust boot over piston after coating with
brake fluid. Install piston into caliper bore pushing it past the
piston seal until it bottoms in the caliper bore (Fig.
7).
CAUTION: Force must be applied to the piston uni-
formly to avoid cocking and binding of the piston in
the bore of the caliper.
Position dust boot in counterbore of the caliper pis-
ton bore. Using a hammer and Installer Piston Caliper Boot,
Special Tool C-4383-7 and Handle, Special Tool
C-4171, drive boot into counterbore of the caliper
(Fig. 8).
Fig. 5 Honing Piston Bore
Fig. 6 Installing New Piston Seal
Fig. 7 Pushing Piston into Bore
Fig. 8 Installing Boot in Caliper
5 - 50 BRAKES Ä

ing, detonation and cooling system malfunctions also
can cause spark plug overheating.
SPARK PLUG SERVICE
When replacing the spark plug and coil cables,
route the cables correctly and secure them in the ap-
propriate retainers. Failure to route the cables prop-
erly can cause the radio to reproduce ignition noise,
cross ignition of the spark plugs or short circuit the
cables to ground.
SPARK PLUG REMOVAL
Always remove the spark plug cable by grasping at
the spark plug boot turning, the boot 1/2 turn and
pulling straight back in a steady motion. (1) Prior to removing the spark plug spray com-
pressed air around the spark plug hole and the area
around the spark plug. (2) Remove the spark plug using a quality socket
with a rubber or foam insert. (3) Inspect the spark plug condition. Refer to
Spark Plug Condition in this section.
SPARK PLUG GAP ADJUSTMENT Check the spark plug gap with a gap gauge. If the
gap is not correct, adjust it by bending the ground
electrode (Fig. 6).
SPARK PLUG INSTALLATION (1) To avoid cross threading, start the spark plug
into the cylinder head by hand. (2) Tighten spark plugs to 28 N Im (20 ft. lbs.)
torque. (3) Install spark plug cables over spark plugs.
POWERTRAIN CONTROL MODULE (PCM)
The ignition system is regulated by the powertrain
control module (PCM) (Fig. 14). The PCM supplies
battery voltage to the ignition coil through the Auto
Shutdown (ASD) Relay. The PCM also controls the
ground circuit for the ignition coil. By switching the ground path for the coil on and off, the PCM adjusts
ignition timing to meet changing engine operating
conditions.
During the crank-start period the PCM advances
ignition timing a set amount. During engine opera-
tion, the amount of spark advance provided by the
PCM is determined by these input factors:
² coolant temperature
² engine RPM
² available manifold vacuum
The PCM also regulates the fuel injection system.
Refer to the Fuel Injection sections of Group 14.
DISTRIBUTOR PICK-UPÐPCM INPUT
The engine speed input is supplied to the power-
train control module (PCM) by the distributor pick-
up. The distributor pick-up is a Hall Effect device
(Fig. 15 or Fig. 16).
A shutter (sometimes referred to as an interrupter)
is attached to the distributor shaft. The shutter con-
tains four blades, one per engine cylinder. A switch
plate is mounted to the distributor housing above the
shutter. The switch plate contains the distributor
Fig. 14 Powertrain control module (PCM)
Fig. 15 DistributorÐ2.2L and 2.5L TBI Engines
Fig. 13 Spark Plug Overheating
8D - 6 IGNITION SYSTEMS Ä

2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNITION SYSTEMSÐDIAGNOSTIC PROCEDURES
INDEX
page page
Coolant Temperature Sensor Test ............ 13
Failure to Start TestÐ2.5L TBI and 3.0L Engines . 12
General Information ....................... 11
Ignition Coil ............................. 11 Manifold Absolute Pressure (MAP) Sensor Test . 13
Poor Performance Test .................... 13
Spark Plugs ............................ 11
Testing for Spark at Coil ................... 11
GENERAL INFORMATION
For additional information, refer to On Board Di-
agnostics in the Fuel Injection General Diagnosis
sections of Group 14. Also, refer to the DRBII scan
tool and appropriate Powertrain Diagnostic Proce-
dures Manual.
SPARK PLUGS
Faulty or fouled spark plugs may perform well at
idle speed, but frequently fail at higher engine
speeds. Faulty plugs can be identified in a number of
ways: poor fuel economy, power loss, decrease in en-
gine speed, hard starting and, in general, poor en-
gine performance. Spark plugs also malfunction because of carbon
fouling, excessive electrode air gap, or a broken insu-
lator. Refer to the General Information Section of
this group for spark plug diagnosis.
IGNITION COIL
The ignition coil is designed to operate without an
external ballast resistor. Inspect the coil for arcing. Test the coil according
to coil tester manufacturer's instructions. Test coil
primary and secondary resistance. Replace any coil
that does not meet specifications. Refer to the Coil
Resistance chart. If the ignition coil is replaced due to a burned
tower, carbon tracking, arcing at the tower, or dam-
age to the terminal or boot on the coil end of the sec-
ondary cable, the cable must be replaced. Arcing at the tower will carbonize the nipple which, if it is con-
nected to a new coil, will cause the coil to fail. If a secondary cable shows any signs of damage,
the cable should be replaced with a new cable and
new terminal. Carbon tracking on the old cable can
cause arcing and the failure of a new coil.
TESTING FOR SPARK AT COIL
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK THE WHEELS BEFORE PERFORMING ANY
TEST WITH THE ENGINE RUNNING.
CAUTION: Spark plug cables may be damaged if
this test is performed with more than 1/4 inch clear-
ance between the cable and engine ground.
Remove the coil secondary cable from the distribu-
tor cap. Hold the end of cable about 6 mm (1/4-inch)
away from a good engine ground (Fig. 1). Crank the
engine and inspect for spark at the coil secondary ca-
ble. There must be a constant spark at the coil second-
ary cable. If the spark is constant, have a helper con-
tinue to crank engine and, while slowly moving coil
secondary cable away from ground, look for arcing at
the coil tower. If arcing occurs at the tower, replace
the coil. If spark is not constant or there is no spark,
proceed to the failure to start test. If a constant spark is present and no arcing occurs
at the coil tower, the ignition system is producing
the necessary high secondary voltage. However,
COIL RESISTANCE
Ä IGNITION SYSTEMS 8D - 11

REMOVAL
(1) Disconnect the coil to distributor ignition cable
(Fig. 4). (2) Disconnect the wiring harness connector from
the coil. (3) Remove ignition coil mounting screws.
INSTALLATION
(1) Install ignition coil onto the bracket. Tighten
the screws to 9.5 N Im (85 in. lbs.) torque. (2) Connect the wiring harness connector.
(3) Connect the coil to distributor ignition cable.
IGNITION COILÐ3.0L ENGINES
The ignition coil is located at the back of the intake
manifold (Fig. 5).
REMOVAL
(1) Remove air cleaner assembly.
(2) Disconnect ignition cable from coil.
(3) Disconnect wiring harness connector from coil.
(4) Remove coil mounting screws.
INSTALLATION
(1) Loosely install ignition coil on intake manifold.
Tighten the intake manifold fastener to 13 N Im(115
in. lbs.) torque. Tighten ignition coil bracket fasteners
to 10 N Im (96 in. lbs.) torque.
(2) Connect the wiring harness connector.
(3) Connect the coil to distributor ignition cable.
(4) Install the air cleaner assembly. Tighten the air
cleaner fasteners to 25 N Im (225 in. lbs.) torque.
SPARK PLUG SERVICE
When replacing the spark plug and coil cables, route
the cables correctly and secure them in the appropriate
retainers. Incorrectly routed cables can cause the radio
to reproduce ignition noise. It can also cause cross
ignition of the spark plugs or short circuit the cables to
ground.
SPARK PLUG REMOVAL
Always remove cables by grasping at boot, rotating
the boot 1/2 turn, and pulling straight back in a steady
motion. (1) Prior to removing the spark plug spray com-
pressed air around the spark plug hole and the area
around the spark plug. (2) Remove the spark plug using a quality socket
with a rubber or foam insert.
Fig. 3 Coolant Temperature SensorÐ3.0L Engine
Fig. 4 Ignition CoilÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines
Fig. 5 Ignition CoilÐ3.0L Engine
Ä IGNITION SYSTEMS 8D - 15