HELP!!! No firm Brake pedal

[RDusch]

OK,

here's the story, i've been bleeding my brakes, i've pushed over 2 quarts thru and bled from every bleeder screw, i even removed the new rear calipers like Paul Herioux recommended I'm 99% sure there no air in the system, but every Time'me i hit the brake pedal it goes straight to the floor, pump it 2 or 3 Time'mes and it comes back up and seems to hold firm with engine off.



start the engine same thing happens but after i pump up the pedal and hold it, it slowly goes down to the floor, and the brake light stays on all the Time.



i just installed a NEW napa master cylinder primed the cylinder with the little tubes going back into the reservoir, re-bled the system and i get the same thing.



another thing that happens, with the top off of the master cylinder if i push on the brake pedal even lightly i get a little geyser from the forward chamber ( both old and new cylinders did the same thing).



i tried plugging both ports on the master cylinder and pushing the pedal hard as a rock won't move a 1/2 inch, question, can the proportioning valve leak between sides?? but then i did not have this problem before i started working on the brakes.



any suggestions i,m about ready to try anything



Rick D

 

[nascar mark]

Hey,



Did you pinch off the lines with vice grips and a piece of rubber before you disconnected the old lines?



Are you bleeding the calipers with the bleed screws at the highest point of the calipers?



Im asume you know how to bleed the system properly!!!!!!!!



mark

 

[RDusch]

Mark,

i had the lined pinched of until i had to remove the old lined to install the new stainless pieces, i did remove the calipers and place the upside down so the bleeders would be on the top, and i did get quit a bit of air out, but still no pedal.



would'nt air give me a mussy pedal but it would hold in place, mine drops to the floor with steady pressure, no leaks and the reservoir level stays the same..... Rick D

 

[nascar mark]

You than have lots of air still in lines when you removed vise grips.

Lots ofair will make the pedal go to the floor. A little air will make pedal mushy. Also with that much pedal to floor you might have hurt bushing in master now. When bleeding you should take your time when pushing pedal down (5 sec min. )



You might be ok so keep bleeding. Not uncommon to use lots of fluid when replacing lines.



mark

 

[dusthomps]

Rick,



Not sure if this will help you or not, but I just got done replacing my master cylinder about 3 weeks ago. I too had bought a new MC from NAPA, primed the cylinder and bled all the lines. With the truck off, I got a very firm pedal, however, with the truck running the pedal went straight to the floor and wouldn't even hold the truck in the driveway. Took it off and had them order me another one. They tested the first one and found that it was defective. They never bothered to tell me what was wrong with it, and I never asked. The second one I put on worked like a charm.

 

[RDusch]

dusthomps

Thanks, i think thats my next move i'll pick one up tomorow night and see if it helps, i just put a vacuum tank on all of my bleeders and pulled another 2 quarts thru with little air showing at all, the pedal is a little better but still slowly sinks then stops about 2" of the floor, i'm going to drive it tomorrow one way or the other.



Rick D

 

[Philip]

Is this an original master cylinder for a disk/drum combo?



If it is you need to put a restrictor into the rear brakes. All disk calipers need to be restricted or they will let the pistons move to far back into the bore. This will give you a weak pedal until it gets the pistons out fully and builds pressure.



The restrictors hold 6psi pressure if I remember right. It has been a while since I have had a class on brakes. So I might be off a little one way or the other on the PSI.

 

[RDusch]

I was just reading about that on TSM mfg. Trouble shooting page looks like i also need to make shure my e brake is adjusted correctly, i was noticeing that the piston does retact enough to let the pad rattle back and for a little..... Rick

 

[Philip]

The e-brake adjustment shouldn't change the pedal any on disks. I wish I could remember who makes the restrictors. I have used some over the years. But it has been a long time since I have needed one I don't remember who made them.



How is the finger doing? I hate it when stuff like that happens in the middle of a project.



If this was a store bought kit. They should have included it with the kit. They know it is needed.

If they don't know it is needed. Then they should find another line of work. Before they get hit with a big law suite from an accident caused with bad rear brakes from an incomplete kit.

 

[keimmmo]

Hey fellas, I went through the exact same problem a few years ago on my '92 4X4. I have NEVER found a service manual that tells what I found to be the problem as an option! My anti-lock solenoid was bad! (It is located inside the driver's side frame rail above the spare tire. )



To verify that the anti-lock solenoid is the problem you can make an eliminator line to bypass it. When I did, I had good brakes again!!! (But no anti-lock. ) Then ordered the solenoid with confidence that it was the problem. Replaced it and solved the problem!



Hope my experience helps. I have seen the same problem on gas vans and pickups too.



Steve