Vaughn Vesay

So here's my problem when my trucks off I can pump the brake up and they get hard, when I start it they go to the floor the truck stops but they still go to the floor changed both calipers with new ones has new pads master cylinder brake booster and shoes all new hard and rubber lines bleed system probably 20-30 times with the same results.

Merfman

Rear Brakes give you a high pedal or full pedal "feel." Check the rear brakes. Replace shoes and drums if needed. If all is good bleed rear brakes. Good luck.

nfld96ford

I have the same problem with my 96 4x4. I'm thinking the booster might have packed it in. Thoughts?

Merfman

Only had one with a bad booster. Pedal was high and rock solid, but you could use both feet and still barely stop. No assist.

nfld96ford

Roger. I have a new master cylinder already, so I went and bought new calipers, wheel cylinders and flex lines. Going to change all those today and give it a good bleeding and hopefully it cures to problem.

nfld96ford

Here's the deal:
1996 F-150 4x4 regular cab long box
-New pads and rotors in December 2013
-New master cylinder in March 2014 (lost pedal then too with no fluid leaks)
Lost pedal again a week ago. Thought there may have been an airlock in the lines/system and started leaving the master cylinder cap off overnight to let any air bubbles rise to the top on their own. I know this is a long shot but I find it helps for small bubbles. No loss of fluid and it's clean.
Requires 2nd pump to get any pedal at all, and pedal will "bleed" all the way to the floor when stopped in traffic and the truck will slowly creep ahead on long stops.
Today I replaced the calipers and wheel cylinders on all four wheels and carefully inspected all the lines and junction blocks for leaks. There was zero sign of any leaks, anywhere.
I then bled all the brakes, starting with the wheel farthest from the master cylinder and working towards it. Pedal bleeding had to be repeated a couple of times to get fluid out the rear bleed screws but once it came, it was good shots and free of air. I repeated the process while keeping the master cylinder full until I was satisfied there was no air in the rear brake circuit. Cap was always on the master cylinder when brake pressure was applied.
I then bled the front, and there was no air present in the front circuit even from the first attempt. My assistant told me the pedal was feeling good, so I checked for myself and sure enough it was nice and high with the engine off. I topped off the master cylinder, re-checked the lines for any leaks and everything was dry. I then adjusted the rear brake shoes by tightening them until the drum wouldn't turn, then backed them off slightly.
The wheels were then put back on, truck put back on the floor and I started the engine thinking I was done and could drive away and everything was fine.
WRONG!
All that work today was for nothing.
The pedal is as bad as it ever was.
I am fairly particular about my vehicles, and I can let some stuff slide a bit but I am very particular about my brakes. One thing I always loved about Ford was the nice brake and good pedal feel, and how easy it is to "get a brake back" after a line has been opened for servicing or replacement.
Any ideas about anything else I can try? Right now I'm thinking my 4 month old master cylinder is garbage, because the brakes are doing exactly the same thing as they were when the original master cylinder packed it in last March. I drove it about 3000 miles or 5000 kms since the master cylinder was replaced and when the trouble started again last week. I might try a used booster just for kicks and see if that fixes anything, as it is likely the old bad master cylinder leaked fluid into the diaphragm of the booster. Thanks for the help!

unit505

I was going to ask you if you've replaced the booster and if you've checked the rod to make sure it hasn't broke? Also, have you checked to make sure that there's no flex with the booster when you step on the brake? The firewall where the booster mounts can crack and allow the booster to flex.

nfld96ford

Thanks for the tip. I haven't checked that out yet, but I will this afternoon. I would think if it were a physical damage issue such as a broken rod or the booster breaking clear of the firewall that the pedal would be soft all the time, not just when the engine is running.

nfld96ford

The firewall, mounting bracket, booster and master cylinder attaching nuts and brake rod are all normal with no apparent damage. The booster+master cylinder moves ahead and back ever so slightly on hard pedal application/release but nothing to cause the pedal to travel the way it does and it looks like the firewall does flex a little but there is no cracks or compromising damage there.

Any other ideas? I'm getting good and poisoned with this.

djfllmn

iTrader: (1)

how are the hoses...a bad hose can throw people for a loop