Opel Frontera UE. Manual - part 1392

 

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Opel Frontera UE. Manual - part 1392

 

 

5C–6

POWER-ASSISTED BRAKE SYSTEM

General Diagnosis

Condition

Possible cause

Correction

Brake Pull

Tire inflation pressure is unequal.

Adjust

Front wheel alignment is incorrect.

Adjust

Unmatched tires on same axle.

Tires with approx. the same amount 
of tread should be used on the same 
axle.

Restricted brake pipes or hoses.

Check for soft hoses and damaged 
lines. Replace with new hoses and 
new double“walled steel brake 
piping.

Water or oil on the brake pads.

Clean or replace.

Brake pads hardened.

Replace

Brake pads worn excessively.

Replace

Brake rotor worn or scored.

Grind or replace.

Disc brake caliper malfunctioning.

Clean or replace.

Front hub bearing preload incorrect.

Adjust or replace.

Loose suspension parts.

Check all suspension mountings.

Loose calipers.

Check and tighten the bolts to 
specifications.

Brake Roughness or Chatter 
(Pulsates)

Excessive lateral runout.

Check per instructions. If not within 
specifications, replace or machine 
the rotor.

Parallelism not within specifications.

Check per instructions. If not within 
specifications, replace or machine 
the rotor.

Wheel bearings not adjusted.

Adjust wheel bearings to correct 
specifications

Pad reversed (steel against iron).

Replace the brake pad and machine 
rotor to within specifications.

Excessive Pedal Effort

Malfunctioning vacuum booster.

Check the vacuum booster 
operation and repair, if necessary.

Partial system failure.

Check the front and rear brake 
system for failure and repair. Also, 
check the brake warning light. If a 
failed system is found, the light 
should indicate failure.

Excessively worn pad.

Check and replace pads in sets.

Piston in caliper stuck or sluggish.

Remove caliper and rebuild.

Fading brakes due to incorrect pad.

Remove and replace with original 

equipment pad or equivalent.

Vacuum leak to vacuum booster.

Check for ruptured or loose hose.

Check the direction of check valve 
within vacuum hose.

Correct vacuum hose direction.

Grease on the brake pads.

Replace or clean.

SECTION

POWER-ASSISTED BRAKE SYSTEM

5C–7

Excessive Brake Pedal Travel

Air in hydraulic circuit.

Bleed the hydraulic circuit.

Level of brake fluid in the reservoir 
too low.

Replenish brake fluid reservoir to 
specified level and bleed hydraulic 
circuit as necessary.

Master cylinder push rod clearance 
excessive.

Adjust

Leakage in hydraulic system.

Correct or replace defective parts.

Brake Drag

Master cylinder pistons not returning 
correctly.

Adjust the stop light switch and 
vacuum booster push rod. If 
necessary, rebuild.

Restricted brake pipes or hoses.

Check for soft hoses or damaged 
pipes, and replace with new hoses 
and new double–walled steel brake 
piping.

Parking brake maladjusted.

Adjust

Parking brake lining clearance 
insufficient.

Adjust

Brake pedal free play insufficient.

Adjust the brake pedal height or 
power cylinder operating rod.

Piston in the master cylinder 
sticking.

Replace

Piston in the disc brake caliper 
sticking.

Replace piston seals.

Brake pads sticking in caliper.

Clean

Return spring weakened.

Replace

Parking brake binding.

Overhaul the parking brakes and 
correct.

Front hub bearing preload incorrect.

Adjust or replace.

Parking brake shoes not returning.

Correct or replace the brake back 
plate and brake shoe as necessary.

Obstructions in hydraulic circuit.

Clean

Rotor warped excessively.

Grind or replace.

Rear brake drum distorted.

Grind or replace.

Parking cable sticking.

Grind or replace.

Grabbing or Uneven Braking Action 
(All conditions listed under “Pulls")

Malfunctioning vacuum booster.

Check operation and correct as 

necessary.

Binding brake pedal mechanism.

Check and lubricate, if necessary.

Corroded caliper assembly.

Clean and lubricate.

Condition

Possible cause

Correction

SECTION

5C–8

POWER-ASSISTED BRAKE SYSTEM

Brake Noisy

Brake pads are worn.

Replace

Brake pads are hardened.

Replace

Brake pads are in poor contact with 
rotor.

Correct

Brake disc(s) warped, worn or 
damaged.

Grind or replace.

Disc brake anti–squeak shims 
fatigued.

Replace

Front hub bearings are loose or 
preload is incorrect.

Adjust or replace.

Brake disc is rusted.

Grind or replace.

Poor Brake Action

Master cylinder faulty.

Correct or replace.

Vacuum booster faulty.

Correct or replace.

Level of brake fluid in reservoir too 
low.

Replenish and bleed.

Air in hydraulic circuit.

Bleed

Disc brake caliper faulty.

Clean or replace.

Water or oil on brake pads.

Clean or replace.

Brake pads in poor contact with the 
rotor.

Correct

Brake pads worn.

Replace

Brake disc rusted.

Grind or replace.

Check valve in vacuum hose faulty.

Correct or replace.

Condition

Possible cause

Correction

SECTION

POWER-ASSISTED BRAKE SYSTEM

5C–9

Hydraulic Brakes

Filling Master Cylinder Reservoir

CAUTION:  Use only specified brake fluid. Do not 
use any fluid which contains a petroleum base. Do 
not use a container which has been used for 
petroleum based fluids or a container which is wet 
with water. Petroleum based fluid will cause 
swelling and distortion of rubber parts in the 
hydraulic brake system. Water mixed with brake 
fluid lowers the fluid boiling point. Keep all fluid 
containers capped to prevent contamination.
Always fill the master cylinder reservoir when the 
engine is cold. 
Never allow the brake fluid to come in contact with 
the painted surfaces. 
The master cylinder reservoir must be kept properly 
filled to ensure adequate reserve and to prevent air 
and moisture from entering the hydraulic system. 
However, because of expansion due to heat 
absorbed from the brakes and the engine, the 
reservoir must not be overfilled. The brake fluid 
reservoir is on the master cylinder, which is located 
under the hood on the left side of the cowl. 
Thoroughly clean reservoir cap before removal to 
avoid getting dirt into reservoir. Remove the 
diaphragm. Add fluid as required to bring level to 
the “MAX" mark on the reservoir tank. Use “DOT 3" 
Hydraulic Brake Fluid. If the fluid cap diaphragm is 
stretched, return it to the original position before 
installing.

Deterioration of Brake Fluid

Using any other brake fluid than specified or brake fluid 
with mineral oil or water mixed in will drop the boiling 
point of brake fluid. It may, in turn, result in vapor lock or 
deteriorated rubber parts of the hydraulic system. Be 
sure to change the brake fluid at specified intervals.
If the rubber parts are deteriorated, remove all the 
system parts and clean them with alcohol. Prior to 
reassembly, dry the cleaned parts with air to remove the 
alcohol. Replace all the hoses and rubber parts of the 
system.

Leakage of Brake Fluid

With engine idling, set shift lever in the neutral position 
and continue to depress brake pedal at a constant pedal 
application force.
Should the pedal stroke become deeper gradually, 
leakage from the hydraulic pressure system is possible. 
Make sure by visual check that there is no leak.

Bleeding Brake Hydraulic System

A bleeding operation is necessary to remove air from 
the hydraulic  brake system whenever air is introduced 
into the hydraulic system. It may be necessary to  bleed 
the hydraulic system at all four brakes if air has been 

introduced through a low fluid level or by  disconnecting 
brake pipes at the master cylinder. If a brake pipe is 
disconnected at one wheel,  only that wheel cylinder/
caliper needs to be bled. If the pipes are disconnected 
at any fitting located  between the master cylinder and 
brakes, then the brake system served by the 
disconnected pipe  must be bled.

1. For 4–Wheel Antilock Brake System (ABS) 

equipped vehicle, be sure to remove the ABS main 
fuse 60A located at the relay and fuse box before 
bleeding air. If you attempt to bleed air without 
removing the main fuse, air cannot be let out 
thoroughly, and this may cause damage to the 
hydraulic unit. After bleeding air, be sure to replace 
the ABS main fuse back to its original position.

2. Set the parking brake completely, then start the 

engine.

NOTE:  The vacuum booster will be damaged if the 
bleeding operation is performed with the engine off.

3. Remove the master cylinder reservoir cap.

4. Fill the master cylinder reservoir with brake fluid.  

Keep the reservoir at least half full during the air 
bleeding operation

5. Always use new brake fluid for replenishment.

6. In replenishing brake fluid, take care that air bubbles 

do not enter the brake fluid.  
When the master cylinder is replaced or overhauled, 
first bleed the air from the master cylinder, then from 
each wheel cylinder and caliper following the 
procedures described below.

Bleeding the Master Cylinder

7. Disconnect the rear wheel brake pipe (1) from the 

master cylinder.
Check the fluid level and replenish as necessary. If 
replenished, leave the system for at least one 
minute.

8. Depress the brake pedal slowly once and hold it 

depressed.

9. Completely seal the delivery port of the master 

cylinder with your finger, where the pipe was 
disconnected then release the brake pedal slowly.

10. Release your finger from the delivery port when the 

brake pedal returns completely.

11. Repeat steps 8 through 10 until the brake fluid 

comes out of the delivery port during step 8.

NOTE:  Do not allow the fluid level in the reservoir to go 
below the half–way mark.

12. Reconnect the brake pipe (1) to the master cylinder 

and tighten the pipe.

13. Depress the brake pedal slowly once and hold it 

depressed.

14. Loosen the rear wheel brake pipe (1) at the master 

cylinder.

SECTION

 

 

 

 

 

 

 

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