1994 Grand Prix 3.1 Liter Brakes

1lasttime
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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by 1lasttime » Mon Sep 16, 2013 5:12 am

The master makes this noise, i cant quite explain. Growling maybe? Lol. And then i can see bubbles in through the front tube.

Just to make sure, the tubes go in the top two ports, and the bottom two ports need plugged if i am using the bleeder pieces that come with the master. Correct?

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carriedi
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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by carriedi » Mon Sep 16, 2013 10:12 am

yes that would be right if that's is what came with the kit. the plugs on the bottom have to be pretty tight or they will draw air on the back stroke.
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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by 1lasttime » Sat Sep 21, 2013 5:33 pm

:? I am completely lost, now. Got the master bled, all air out of the lines, had bakes, now back to square one. I was told that since the pressure builds up as i press the brake peddle and the pressure doesnt release, it has to be the back rubber lines that run from the caliper to the brake line. I have now replaced those. Went around and rebled all brakes again. Took it for a test drive and still the same issue. It builds up pressure. If i release any of the bleeder screws, fluid sprays out like old faithful. I then have regular brakes again until i drive and press on the brake the pressure builds up more and more as i press on the brake. :shock: here is a list of new parts- rear calipers (both sides) rear rubber lines (both sides) master cylinder rear brake pads rear rotors.

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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by 1lasttime » Mon Oct 07, 2013 7:16 pm

Update: here is everything i have done,

Rear:
Calipers
Brake pads
Rotors
Soft hoses
And parking brake cables (done by auto mechanic shop)

Master replaced

When the brakes tighten up i have bled them from the front and it releases the pressure. They tightened up today and i was told by a mechanic to pull the hose and the connector from the booster and see if that releases it. That did not help, i again had to release the pressure from the front calipers.

They are all bled properly. My dad who was a mechanic said there has to be a kink somewhere. Any ideas at all besides that?

I really appreciate ALL the help!

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carriedi
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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by carriedi » Wed Oct 09, 2013 9:00 pm

hydraulics work on a very basic system, pressure. if you know that opening the bleeder screw releases the pressure and frees up the wheel stop opening the bleeder screw. You already know that there is a system component that is not letting the pressure off the brake system. From that point you have to move back up the system and see where the pressure is being blocked.

First: opening the bleeder releases the wheel. ok, a known pressure build up
second: when the pressure is holding again open the connection at the steel line from the body and the flexible brake hose. If it realeases the pressure there go to the next step
third: when the pressure is built up again, putting pressure of the brake system open the connection between the brake line and the master cylinder. If it releases the pressure there you have
to look at what can cause the pressure to not return to the brake release port.
forth: when the pressure is up again and causing the brakes to be applied unbolt the master cylinder from the brake booster. (do not loosen or remove the brake lines from the master) Move
the master about an inch away from the booster. does that release the pressure on the brake system? If it does release the brake pressure your Booster is not correct for your master cylinder. It could have internal damage and not returning to the at rest position. Replase the booster. If the brake system is still under pressure after you move it away from the booster you have a problem with your master. Things that can cause the master to act up like this is contamination of the brake fluid with some kind of petroleum product (causes the master seals to swell and close over the port) or debris build up in the brake system (acting like a check valve)
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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by 1lasttime » Sun Oct 13, 2013 5:55 pm

Okay, found the problem. There is air getting into the master. How? Your probably going to know that before me. I have bench bled it until there are absolutely no bubbles whatsoever. It is just plain clear fluid. I place it on the car hook the lines up tight and go to get the brakes bled there is a humming from the cylinder and no fluid from the lines. The front lines wont even gravity bleed. And the front now has new rubber hoses to add to the previous list. I have tested out the booster. It has passed everything everyone has told me to do.

I checked the lines (with brakes compressed) at the master when i break them open, the bottom front and the top back has fluid drain from them, but the top front and the bottom back are dry. Just another symptom to add. And this a another new brake cylinder. I returned the other other one as it had a seal leak.

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carriedi
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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by carriedi » Mon Oct 14, 2013 1:30 am

ok, lets see if I can understand what is going on... you bench bleed the master and all four ports have brake fluid going through the hoses back to the reservoir right? If that is so, bolt up the master to the booster with the bleeder hoses still attached. Without starting the engine, push on the brake pedal and see if you still have fluid going through all four ports. If that's all good hook up you steel brake lines and tighten them up.

without starting the engine, bleed the brakes at the bleeder screws. The vacuum booster will make it harder to push the pedal down but you must push the pedal down until the pedal hits the floor or no air comes out anymore. It may take a while to get all the air out because you have replaced so many things. Don't pump the pedal fast. That will just aerate the fluid. Long steady strokes.

RR - LF - LR - RF
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Re: 1994 Grand Prix 3.1 Liter Brakes

Unread post by 1lasttime » Mon Oct 14, 2013 9:57 am

Its during that process that air gets back into the cylinder. I have removed the brake line to the master, hookes the bleeder hoses back up (yes into the reservoir) and a bunch of air will be in the master. I did the pedal to the floor, got fluid out through both front, pedal down open bleeder close bleeder then pedal up, but now the front brakes are VERY tight. (Not releasing pressure) there is air back in the cylinder AGAIN. I will be taking it to a shop either today or tomorrow. Hopefully they can fix it with a vacuum bleeder.

I thank you for ALL of your help! It was on here that actually helped me figure out there was air in the master. :-) Again, thank you!!!

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