1994 Fullsize Pickup, No Brake Pedal?

[notyepcars]

Working on a 94 chev fullsize pickup. Main brake line rusted thru along frame rail, my brother had to use Emergency brake to stop vehicle. It has been sitting about 6 months. Replaced entire line from front of truck to rear, and over to right rear, trying to bleed brakes but getting no pedal, however fluid to all four wheels. After trying to bleed 50 times, I went and purchased a new master cylinder, no change, geting fluid with no air to all four wheels but absolutetly no pedal. Brake light in dash come's on sometimes and off others. I suspected the proportioning valve, unsure how to reset this, or how far the little pecker should stick out. Easily have pumped over 2 gallons of fluid thru this with no change at all. Hooked up snap-on scanner, no codes whatsoever, no ABS light. This thing is kicking my butt!! Any help would be great.

[Nytemare]

Working on a 94 chev fullsize pickup. Main brake line rusted thru along frame rail, my brother had to use Emergency brake to stop vehicle. It has been sitting about 6 months. Replaced entire line from front of truck to rear, and over to right rear, trying to bleed brakes but getting no pedal, however fluid to all four wheels. After trying to bleed 50 times, I went and purchased a new master cylinder, no change, geting fluid with no air to all four wheels but absolutetly no pedal. Brake light in dash come's on sometimes and off others. I suspected the proportioning valve, unsure how to reset this, or how far the little pecker should stick out. Easily have pumped over 2 gallons of fluid thru this with no change at all. Hooked up snap-on scanner, no codes whatsoever, no ABS light. This thing is kicking my butt!! Any help would be great.

That is absolutely weird man.

There is no leaks from any of the front lines are there??

[8D3]

What condition are the pads and shoes in?The front lines arent swelled are they?Even with spongy lines and wore out pads/shoes,you would think you would get some pedal.Sitting for that long and then total replacement of lines can do strange things.I have fought this on 4 wheelers before,get all kinds of fluid at the caliper but still weak lever,just had to keep bleeding.The little mighty vac unit helps in those cases.

[Nytemare]

You may have a defective master cylinder too. I have seen this happen lots of times...sometimes they sit on the shelf too long and the o-rings on the shaft dries out and when you get it and push the peddle it just crumbles inside the M/C and you get no pressure.

[notyepcars]

You may have a defective master cylinder too. I have seen this happen lots of times...sometimes they sit on the shelf too long and the o-rings on the shaft dries out and when you get it and push the peddle it just crumbles inside the M/C and you get no pressure.

 

Should I be bleeding this truck with the engine off key off, engine off key on, or engine running. I have not pulled the wheels off to look at the pads or the shoes but they are not leaking. I really lose pedal when I start the truck, I could pus=h it to the floor with my pinky finger. also I am used to the pump them up and hold type system. Shop manual says pump pedal once, wait 15 seconds then crack bleeder. What works better. Thanks

[Nytemare]

You may have a defective master cylinder too. I have seen this happen lots of times...sometimes they sit on the shelf too long and the o-rings on the shaft dries out and when you get it and push the peddle it just crumbles inside the M/C and you get no pressure.

 

Should I be bleeding this truck with the engine off key off, engine off key on, or engine running. I have not pulled the wheels off to look at the pads or the shoes but they are not leaking. I really lose pedal when I start the truck, I could pus=h it to the floor with my pinky finger. also I am used to the pump them up and hold type system. Shop manual says pump pedal once, wait 15 seconds then crack bleeder. What works better. Thanks

 

I use the pump pump pump........pump some more and than bleed

But there is a new tube out there that pushes the fluid in through the bleed screw, and therefore the air escapes through the master cylinder. It gets pushed up and out instead of down like we always did it. Seen it on Gearz.

 

I don't do it with the engine running as its so easy to push the peddle to the floor. Also...I IIRC...its recommended to not do it that way either.

 

Only thing I can think of is remove the new master cylinder bring it back and get a new one. Just tell them its not holding pressure. Its worth a try...and it wont cost you anything.

Also....the old one was toast too...the truck should have had front brakes even with the rear line broken...its split in two chambers so if a line breaks you should always have brakes....unless you are unlucky enough to break 2 lines.

[minibike132]

There is nothing to reset on this one. Crack all the bleeders and keep an eye on the master. When it gets low top it off, keep doing this (gravity bleeding) untill you go through at least one pint of fluid, I've had it take 2 before. Close them all up, do not pump the pedal, have someone push it to the floor and open a bleeder (right rear, left rear, right front, then left front). Close the bleeder and let the pedal up, repeat 4 or 5 times then move on to the next one. Don't use the pump pump pump or even one pump. There is ALOT of air in this thing and even one pump agitates everything moving the air back upstream. Let this thing gravity bleed then do the straight to the floor bleed at all wheels and you should be good to go. This all assumes that you bench bleed the master before installing.

 

I have done lines on these things alot and that includes ones that were dry for awhile. This method has yet to fail me, just make sure you keep an eye on that master while it's gravity bleeding DO NOT LET IT GO DRY. It will go surprisingly fast once it starts going, you might get 10-15 min from full to the top to bone dry.

 

It is a pretty quick replace on that master too if you want to swap it out for another new one before starting.