1991 1999 ford explorer chilton User Manual

							Booster pushrod gauge adjustment procedure
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Cutaway view of the vacuum assisted power brake booster assembly Click to enlarge
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REMOVAL & INSTALLATION 979 
						

							Booster mounting
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980 REMOVAL & INSTALLATION 
						

							Booster vacuum hose connections for the 2.3L & 2.9L engines£.0L engine similar to 2.9L
engine
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REMOVAL & INSTALLATION 981 
						

							Booster vacuum hose connections for the 3.0L-4.0L engine similar
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Disconnect the stop lamp switch wiring to prevent running the battery down.
1. 
Support the master cylinder from the underside with a prop.
2. 
Remove the master cylinder-to-booster retaining nuts.
3. 
Loosen the clamp that secures the manifold vacuum hose to the booster check valve, and remove the
hose. Remove the booster check valve.
4. 
Pull the master cylinder off the booster and leave it supported by the prop, far enough away to allow
removal of the booster assembly.
5. 
From inside the cab on vehicles equipped with push rod mounted stop lamp switch, remove the
retaining pin and slide the stop lamp switch, push rod, spacers and bushing off the brake pedal arm.
6. 
From the engine compartment remove the bolts that attach the booster to the dash panel.
7. 
To install: Mount the booster assembly on the engine side of the dash panel by sliding the bracket mounting
bolts and valve operating rod in through the holes in the dash panel.
8. 
Make certain that the booster push rod is positioned on the correct side of the master cylinder to install
onto the push pin prior to tightening the booster assembly to the dash.
From inside the cab, install the booster mounting bracket-to-dash panel retaining nuts.
9. 
Position the master cylinder on the booster assembly, install the retaining nuts, and remove the prop
from underneath the master cylinder.
10. 
Install the booster check valve. Connect the manifold vacuum hose to the booster check valve and
secure with the clamp.
11. 
From inside the cab on vehicles equipped with push rod mounted stop lamp switch, install the bushing
and position the switch on the end of the push rod. Then install the switch and rod on the pedal arm,
along with spacers on each side, and secure with the retaining pin.
12. 
Connect the stop lamp switch wiring.
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982 REMOVAL & INSTALLATION 
						

							Start the engine and check brake operation.
14. 
Brake Hoses and Lines
Metal lines and rubber brake hoses should be checked frequently for leaks and external damage. Metal lines
are particularly prone to crushing and kinking under the vehicle. Any such deformation can restrict the proper
flow of fluid and therefore impair braking at the wheels. Rubber hoses should be checked for cracking or
scraping; such damage can create a weak spot in the hose and it could fail under pressure.
Any time the lines are removed or disconnected, extreme cleanliness must be observed. Clean all joints and
connections before disassembly (use a stiff bristle brush and clean brake fluid); be sure to plug the lines and
ports as soon as they are opened. New lines and hoses should be flushed clean with brake fluid before
installation to remove any contamination.
REMOVAL & INSTALLATION Disconnect the negative battery cable.
1. 
Raise and safely support the vehicle on jackstands.
2. 
Remove any wheel and tire assemblies necessary for access to the particular line you are removing.
3. 
Thoroughly clean the surrounding area at the joints to be disconnected.
4. 
Use a brush to clean the fittings of any debris
Place a suitable catch pan under the joint to be disconnected.
5. 
Using two wrenches (one to hold the joint and one to turn the fitting), disconnect the hose or line to be
replaced.
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Brake Hoses and Lines 983 
						

							Use two wrenches to loosen the fitting. If available, use flare nut type wrenches
Disconnect the other end of the line or hose, moving the drain pan if necessary. Always use a
back-up wrench to avoid damaging the fitting.
7. 
Disconnect any retaining clips or brackets holding the line and remove the line from the vehicle.
8. 
If the brake system is to remain open for more time than it takes to swap lines, tape or plug each
remaining clip and port to keep contaminants out and fluid in.
Any gaskets/crush washers should be replaced with new ones during installation HOW TO USE THIS BOOK
984 REMOVAL & INSTALLATION 
						

							Tape or plug the line to prevent contamination
To install:
Install the new line or hose, starting with the end farthest from the master cylinder. Connect the other
end, then confirm that both fittings are correctly threaded and turn smoothly using finger pressure.
Make sure the new line will not rub against any other part. Brake lines must be at least 1/2 in. (13mm)
from the steering column and other moving parts. Any protective shielding or insulators must be
reinstalled in the original location.
9. 
WARNING
Make sure the hose is NOT kinked or touching any part of the frame or suspension after installation. These
conditions may cause the hose to fail prematurely.
Using two wrenches as before, tighten each fitting.
10. 
Install any retaining clips or brackets on the lines.
11. 
If removed, install the wheel and tire assemblies, then carefully lower the vehicle to the ground.
12. 
Refill the brake master cylinder reservoir with clean, fresh brake fluid, meeting DOT 3 specifications.
Properly bleed the brake system.
13. 
Connect the negative battery cable.
14. 
Bleeding The Brakes WARNING
Vehicles with 4-wheel anti-lock brakes require an Anti-lock Brake Adapter (T90P-50-ALA) and Jumper
(T93T-50-ALA) in order to bleed the master cylinder and the Hydraulic Control Unit (HCU). Failure to do
so will trap air in the HCU unit, eventually causing a spongy pedal. The tools are not required for caliper or
wheel cylinder bleeding procedures.
When any part of the hydraulic system has been disconnected for repair or replacement, air may get into the
lines and cause spongy pedal action (because air can be compressed and brake fluid cannot). To correct this
condition, it is necessary to bleed the hydraulic system after it has been properly connected to be sure all air is
expelled from the brake cylinders and lines.
When bleeding the brake system, bleed one brake cylinder at a time, beginning at the cylinder with the longest
hydraulic line (farthest from the master cylinder) first. ALWAYS Keep the master cylinder reservoir filled
with brake fluid during the bleeding operation. Never use brake fluid that has been drained from the hydraulic HOW TO USE THIS BOOK
Bleeding The Brakes 985 
						

							
system, no matter how clean it is.
It will be necessary to centralize the pressure differential value after a brake system failure has been corrected
and the hydraulic system has been bled.
The primary and secondary hydraulic brake systems are individual systems and are bled separately. During
the entire bleeding operation, do not allow the reservoir to run dry. Keep the master cylinder reservoir filled
with brake fluid.
Clean all dirt from around the master cylinder fill cap, remove the cap and fill the master cylinder
with brake fluid until the level is within  1
/4  in. (6mm) of the top edge of the reservoir.
1. 
Clean off the bleeder screws at all 4 wheels. The bleeder screws are located on the inside of the brake
backing plate, on the backside of the wheel cylinders and on the front brake calipers.
2. 
Attach a length of rubber hose over the nozzle of the bleeder screw at the wheel to be done first. Place
the other end of the hose in a glass jar, submerged in brake fluid.
3. 
Bleed the rear brakes first, ensuring that no air bubbles remain visible moving through the tubing
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986 Bleeding The Brakes 
						

							Bleed the caliper until you can see clean, air bubble free brake fluid moving through the tube
Open the bleeder screw valve  1
/2 - 3
/4  turn.
4. 
Have an assistant slowly depress the brake pedal. Close the bleeder screw valve and tell your assistant
to allow the brake pedal to return slowly. Continue this pumping action to force any air out of the
system. When bubbles cease to appear at the end of the bleeder hose, close the bleeder valve and
remove the hose.
5. 
Check the master cylinder fluid level and add fluid accordingly. Do this after bleeding each wheel.
6. 
Repeat the bleeding operation at the remaining 3 wheels, ending with the one closet to the master
cylinder. Fill the master cylinder reservoir.
7. 
Chilton® Automotive Information Systems. © 2004 Thomson Delmar Learning. HOW TO USE THIS BOOK
Bleeding The Brakes 987 
						

							
FRONT DISC BRAKES
Introduction
Exploded view of the 1991-94 front disc brake assembly-4-wheel ABS sensor not shown Click to enlarge
FRONT DISC BRAKES 989