frein Buick Regal 1991

[davy]

Bonjour à tous,  un petit nouveau et Français en plus, d'ALSACE pour être plus précis. Si je me joins à vous c'est pour vous exposer mon problème en espérant que vous pourrez m'aider.

Mon père possède une Buick Régal Limited V6 3.1 de 1991. Quand il freine, il y a comme un bruit de pompe qui s'actionne mais il y a 15 jours, en freinant  normalement , le bruit à cessé et la voiture n'a plus eu de frein du tout. Les disques et plaquettes avant et arrière sont neufs, les étriers avant sont neufs,  les purges ont été faites mais là plus rien ne fonctionne. La pédale est molle, le liquide de frein n'arrive plus aux étriers. j'ai vérifié tout les fusibles et relais lié aux freins et ABS  mais tout est Ok. il n'y a pas de perte de liquide et le réservoir est plein. Je ne sais plus quoi vérifier.

Avez-vous une idée?   

Bonne journée a tous 

 

Hello everyone, a new kid and a Frenchman at that, from ALSACE to be more précise.
 If I join you it is to explain my problem to you in the hope that you can help me.
My father owns a Buick Régal Limited V6 3.1 from 1991. 
When he brakes, there is a sound like a pump activating but 15 days ago, when braking normally, 
the noise stopped and the car no longer has had no brake at all. The front and rear discs and pads are new,
 the front calipers are new, the bleeding has been done but nothing works anymore.
 The pedal is soft, the brake fluid no longer reaches the calipers.
 I checked all the fuses and relays related to the brakes and ABS but everything is OK.
 there is no loss of fluid and the tank is full. I don't know what to check anymore.
Do you have an idea?
Good day to all

 

Edited September 18 by davy (see edit history)

[Frank DuVal]

Sounds like the ABS system was activating (the pump activating noise). I do not know the reason. But if the accumulator, on the ABS unit, got empty it needs to be refilled. Someone with a shop manual might be along to answer how to do it.

 

Or, Is just removing the ABS unit allowed under your laws? You would need to reflare the lines and use an inverted flare connector to do this, or find four adapters that fit the existing lines at the ABS unit to do it.

[davy]

Good evening, Thank you for your help. We have no particular obligation on ABS. I didn't know you could remove the ABS system. But I will only do this as a last resort. As for filling the accumulator, if someone could explain the procedure to me, I would be grateful.

[Rusty_OToole]

There is a special procedure for bleeding the ABS system. Usually done by a dealer with special equipment. If you wish to do it yourself here is how it is done.

 

BLEEDING OLDER INTEGRAL ABS SYSTEMS

Integral ABS systems were discontinued long ago, but you may still encounter this type of ABS system on some older vehicles. The GM applications include the Delco III Powermaster system on 1989-91 Buick Regal, Oldsmobile Cutlass and Pontiac Grand Prix and GTU models. It is functionally similar to the Teves Mark 2, Bosch III and Bendix 9 and Bendix 10
integral ABS systems used on older GM, Ford and Chrysler vehicles.

Integral ABS systems use a high pressure pump and accumulator for power assisted braking as well as anti-lock braking. As a rule, the accumulator must be depressurized before doing any type of brake repair work. Some of these systems can produce pressures of up to 2,700 psi, so never open a brake line or attempt to replace any of the ABS hydraulic components until the accumulator has been fully depressurized. This is done by pumping the brake pedal firmly 40 times with the ignition off.

After repairs have been made, the lines can be bled manually, with a conventional power bleeder, injector tool or vacuum bleeder. With all of these methods, leave the key off so the ABS pump does not pressurize the accumulator. Each of the brakes can then be bled in the usual manner following the sequence recommended by the vehicle manufacturer. On the GM cars, the usual sequence is right rear, left rear, right front and left front.

If the master cylinder or ABS modulator has been replaced, or there is air in either unit, the ABS modulator will have to be bled using a specific procedure. On the older GM applications with the Powermaster III ABS system, here is the recommended procedure:
 

1.  
2. To bleed the isolation valves in the modulator, there are two bleeder screws. Start with the one toward the engine. Turn the ignition on and apply light pressure on the brake pedal. Open the bleeder screw and allow the fluid to flow until clear. Close the screw and do the same at the second bleeder screw.
    
   •  
   • Depressurize the accumulator by pumping the pedal 40 times with the key off. Wait about two minutes for the brake fluid to de-aerate, then refill the fluid reservoir with DOT 3 brake fluid.
      
     •  
     • Now you can bleed the boost section. This is done by applying moderate pressure on the brake pedal and turning the ignition on for three seconds, then off. Repeat this a total of 10 times. Make sure the pedal feels firm when you have finished, and give the car a road test to make sure the brakes are working properly.
       
       Note: There is also a solenoid bleed test option you can use if you have a Tech 2 scan tool. This will cycle the hold and release solenoids to purge air from the booster.

Edited September 18 by Rusty_OToole (see edit history)

[davy]

Hello, thank you for your answer. I will try this procedure. Is it possible to remove everything and replace with a simpler and more basic system?

[Rusty_OToole]

10 hours ago, davy said:

Hello, thank you for your answer. I will try this procedure. Is it possible to remove everything and replace with a simpler and more basic system?

It is possible to disconnect the ABS unit and pipe the master cylinder directly to the wheels. Eliminating the ABS.

[davy]

ok, I think that's what I'm going to do. Thanks for the help. I will get back to you.

[EmTee]

ABS activating when a wheel was not slipping can be caused by a bad wheel sensor.  On this Buick, the sensor is integral to the wheel hub (bearing assembly).  When the wheel bearing fails, the grease seal is damaged and metal filings mixed with grease from the worn bearing can foul the sensor tone wheel, causing erroneous ABS activation - particularly as the car slows just prior to coming to a stop.  So, whatever you do to repair the brakes should include a check of the four wheel hub bearings.

[davy]

the wheel hub and bearing were cleaned during the disc and caliper change. The problem really comes from a total lack of fluid pressure in the calipers.

[EmTee]

Agree, I wasn't sure whether you were experiencing erroneous ABS activation before the loss of brake function.  Just wanted to make sure you didn't have two separate problems.

[davy]

No problem.
Indeed, brake problems are linked to ABS failure.