more brake problems

[fritzsch]

Hey

So I bought a 87 AMC Eagle couple months ago and I have been dealing with brake problems ever since and I would like some help. So first of all, the brake pedal would always slowly start to sink when I applied pressure, so I replaced the brake master cylinder and in the process broke a brake line which I spliced and fixed and I am pretty sure it is not leaking from there.

Now my current problem is that braking force leaves a lot to be desired, I can hit the brake pedal but the car just slowly stops, not at all what I would expect from the force to the pedal. It doesn't seem like the pedal travel or braking distance changes after several attempts. Also when I apply the brakes I hear a hissing sound inside the cabin, probably would hear it if I was outside as well but I cant apply the brakes and have a head in the engine bay at the same time.

So what do you guys think could be my problem and solution?

[AMC of Houston]

Well, may be time for a new power booster.

[eaglefreek]

Sounds to me like air in the lines. How did you nleed the master cylinder? I haven't had much success bleeding new masters with the ports plugged like they come now. I liked the old method with tubes going from the ports to resovoir.

[eagleman]

I second the thoughts on the booster. If your master cylinder was leaking from the back you can bet that the booster sucked in brake fluid and ate through the diaphram. Probably where you are hearing the hissing sound now. Changing the booster is a real fun job. Ask me how I know lol. Anyway good luck with repairing your brakes.

[fritzsch]

Yeah master cylinder was leaking from the back, so looks like it is time for a new brake booster. Does anyone have a nice "How to" or advice on that?

[BenM]

Not so much a how to, but you really want to take the hood off for that. I recall the booster being very difficult to get out due to closeness to the shock tower.

[eagleman]

Here's how I did mine. I did not remove the hood although it would have been easier if I had but had no one to help me get it off so I worked around it. First disconnect the neg battery cable. Then unbolt the master cylinder from the booster and pull it forward as far as possible without disconnecting the brake lines or bending them.Then from under the dash disconnect the booster push rod from the brake pedal along with the brake switch. Then pull off the vacumn hose that runs to the booster with out breaking the check valve. Not remove four nuts that secure the booster to the brackets mounted to the fire wall. Do not attempt to remove the brackets from the firewall. After you have the four nuts off pull the booster forward. You will find that the booster will not clear the shock tower and allow removal. So here is how I did it. I pulled the booster forward on the fender side until the finder side studs were out of the mounting holes. Then I used a pry bar and slowly pried the top stud out of the top hole and rotated the booster toward the motor allowing only bottom stud on the motor side left in the mounting bracket. Once this is done you can now pull the booster forward and remove. Then go have a beer or a coke cause you earned it! Instalation is just reverse or the above steps just make sure you get the inside bottom stud in the mounting bracket first then the inside top. Then using your pry bar again slowly pry the booster over until the two outer studs slip into the mounting holes. Reinstall the four nuts then go have another coke and come back and finish the install job. Good luck and hope this helps.

[fritzsch]

Thanks Eagleman!

Would it help if the master cylinder was removed? I am thinking about removing it to bleed it again, and make sure I got all the air out of it.