87 deville. Stumped on a brake problem.

I have a 87 deville with front wheel drive.
My breaks are really squishy. Sometimes when I press all the way down they have a weird feeling. A little like an ABS vibration but I don't think thats what it is.
I have no leaking break fluid. I have bled all the lines all the way through. All the breaks look fine. Is there something in the master cylander I have to bleed?

Welcome to AF. Was any work done that created this problem? Your description is vague so it is difficult to make a meaningful suggestion here, does the dash brake lite come on, does the car have reasonable stopping power? "Weird feeling "is tough to picture what you mean!

Welcome to AF. Was any work done that created this problem? Your description is vague so it is difficult to make a meaningful suggestion here, does the dash brake lite come on, does the car have reasonable stopping power? "Weird feeling "is tough to picture what you mean!

So very sorry.
I have a very hard time stopping. They are very squishy. Brake light and the ABS lights are on.
It had a slow break fluid leak. It got so empty that I had to bleed the whole system. Then strange as it seems the leaked stopped. But unfortunately the stopping power is gone too.
So I have bled the whole system and checked the pads, shoes, drums, rotors, calipers and rear cylanders. They all seem fine.
Thanks.

How did you bleed it? Manually or with a power bleeder? It sounds like you still have some air somewhere in the lines.

I bled them with a power bleeder. I bled about a half cup to a cup out of each line starting with the brake furthest from the master cylander and working my way in. There was no change.

I am bumping this thread because I still have no idea what the problem may be. Please give me a hand.

Consider the possibility of a bad master cylinder and that you may only be getting fluid pressure to the fronts or the rears. You mentioned a leak. Did you determine the source at any point? Was it visible? If not that leads us back to the master cylinder.

I was really hoping someone wouldn't say that. I never found the location of the leak for sure and now it is gone like I said. The Master cylinder on this thing is called a power cylinder, I believe. I think it costs as about as much as a transmission also. So fixing it was my hope if that was the case. It is the size of a small transmission. I seems to have some kind of a ball that I think may be a reservoir. Kind of like radiator heat for your home functions. So I was thinking that maybe I needed to bleed that in some kind of a fashion. Here is a picture of the master cylander.
http://motomutz.com/misc/damcar1.jpg


http://motomutz.com/misc/damcar2.jpg

http://motomutz.com/misc/damcar3.jpg

Looks like the leak is back. It is very slow and I have not found the source. No breakfluid on the firewall behind the master cylander. Please. Does anyone know about these monsters?

If you can't locate a visible leak the MC may be leaking into the booster and the fluid sucked into the engine and burned.
You might try a Caddy recycler like www.cadauto.com or investigate whether a rebuilding kit is available for it. Unless the cylinder is pitted, new seals might fix you up.
FWIW
YMMV

That " ball " is the accumulator for the abs, this is a unitized system and there are really no field repairs done. As mentioned try to make sure there is no line in the under chassis leaking or some other hidden area not discovered

My 90 developed a leak in the line running in front of the fuel tank. Needed four eyes to find it, as the fluid would spray on the tank.