need a little help(brake prob)

[O'neal]

Here's the deal....I swapped in a 91 runner rear,forgot to tighten down a fitting lost some fluid and probably sucked in some air while I was getting it turned around to put it in the garage better.
The brake's worked fine with the old 84 axle but dont worth a crap now,got to pump them twice to get some stoppage.
I bled the crap out of the brake's,the master then the wheel's then the prop valve,no visible leak's,changed the master off of a part's truck although it felt bad before I pulled it.Pedal pressure feel's ok but not good though when it isn't running.When running the pedal goes to the floor.The pedal feel's different when running than not.
I'm thinking it's the master cylinder going out but I dont know.I know that when I'm in moab I need brake's.Does this make sense?

 

[DaveB]

Here's the deal....I swapped in a 91 runner rear,forgot to tighten down a fitting lost some fluid and probably sucked in some air while I was getting it turned around to put it in the garage better.
The brake's worked fine with the old 84 axle but dont worth a crap now,got to pump them twice to get some stoppage.
I bled the crap out of the brake's,the master then the wheel's then the prop valve,no visible leak's,changed the master off of a part's truck although it felt bad before I pulled it.Pedal pressure feel's ok but not good though when it isn't running.When running the pedal goes to the floor.The pedal feel's different when running than not.
I'm thinking it's the master cylinder going out but I dont know.I know that when I'm in moab I need brake's.Does this make sense?

Sounds like a leaky master cylinder to me.
Dave

 

[KToy]

hmmmm that sucks... maybe have a shop to a power bleed with a machine so it sucks 100 percent of the air out... and we had to bleed my friends runner for about 30 40 minutes to get it to build pressure.... now it stops fine with a ifs rear end in it.

 

[RockPaws]

If you've bled all the air from the system. Then I woudl suspect the Master Cylinder is bypassing internally. If you can pump it up, theirs air in the system.

 

[O'neal]

Thank's for the responses.Now tell me if this is right.....When the truck is running with my foot on the brake pedal I have to pump twice to get any pedal now when I shut the motor down with my foot still on the pedal it rises back up,Is there something wrong with the booster also,Ive never noticed this before?.

 

[camicaztoy]

nope, what your describing is a result of air in the system.

 

[DaveB]

nope, what your describing is a result of air in the system.

I agree with air in the system, if the master cylinder were leaking the pedal would slowly go to the floor while under pressure.

 

[O'neal]

The pedal does not bleed off while under pressure(foot holdin pedal down) so I guess I need to bleed them some more.
Start from the furthest wheel and work to the front such as pass rear,driver rear,load prop valve,front pass to driver...right? This suck's

 

[KToy]

i have never blead the proportioning valve..... ever...

when we did my truck and my friends truck we did it with the truck running so that the vacuum assist would help bleed it better....

so maybe try it with your motor running

and i also concur there is air in the line.

 

[PierCed_3]

after trying to bleed my brakes for 1 day straight I took it to Big-O and had them pressure bleed it. It was worth the 25 bucks, and I can now stop .

 

[O'neal]

after trying to bleed my brakes for 1 day straight I took it to Big-O and had them pressure bleed it. It was worth the 25 bucks, and I can now stop .

I was thinking of doing the same.Did they do it on the vehicle?

 

[O'neal]

i have never blead the proportioning valve..... ever...

when we did my truck and my friends truck we did it with the truck running so that the vacuum assist would help bleed it better....

so maybe try it with your motor running

and i also concur there is air in the line.

I've been on my own for the last few day's,dont have anybody to pump while I release the fitting's...I tried to do the one man deal with the little kit from the part's store,it worked alittle.
It's going on the trailer tomarrow afternoon and I'll either run it to a shop before or bleed them when I meet my buddies in moab,either way they are going to work cause i'm not pulling it 300 miles to let it sit on the trailer
Thank's for all the input and maybe I'll see some of you down there.

 

[Ohms]

Just a quick tip in case you didn't know- when your bleeding the brakes...when you crack the bleeder screw don't just let the fluid squirt a bit and then tighten it back down....hold it open for a little bit to let ALL the air out not just the first few spurts. Cuts down on the bleeding time and gets better results. If you don't you can get the issues your describing.

 

[Caleb]

Just a quick tip in case you didn't know- when your bleeding the brakes...when you crack the bleeder screw don't just let the fluid squirt a bit and then tighten it back down....hold it open for a little bit to let ALL the air out not just the first few spurts. Cuts down on the bleeding time and gets better results. If you don't you can get the issues your describing.

this can introduce air back intot he system if you let the brake go to the end of the stroke while ther bleeder screw is opened. If you can't get eth one man brake bleeder to work I would suggest gravity bleeding them. It works great adn soemtiems you have to gravity bleed them as pressure bleeding them (home style ) wil sometimes break up the air pockets into little air bubbles that will get trapped in little nooks and ridges. Or you can jsut take it to a shop and have them pressure bleed them.

 

[camicaztoy]

start with the brakes closest to the master and work your way out. so it would be rf, lf, rr, lr. also if you've got a napa or a carquest up there they sell speed bleeders which work great for one man break bleeding.

 

[heinz]

start with the brakes closest to the master and work your way out. so it would be rf, lf, rr, lr. also if you've got a napa or a carquest up there they sell speed bleeders which work great for one man break bleeding.

I though it was the oppisite way also (furthest to closest to master cylinder)

 

[O'neal]

this can introduce air back intot he system if you let the brake go to the end of the stroke while ther bleeder screw is opened. If you can't get eth one man brake bleeder to work I would suggest gravity bleeding them. It works great adn soemtiems you have to gravity bleed them as pressure bleeding them (home style ) wil sometimes break up the air pockets into little air bubbles that will get trapped in little nooks and ridges. Or you can jsut take it to a shop and have them pressure bleed them.

Never heard of gravity bleeding,how is it done?

 

[Caleb]

Never heard of gravity bleeding,how is it done?

its super simple (but very effective), you open all your bleeder screws (or atleat the ones you need to bleed), then you pop off you MC cap and watch them bleed, never let the fluid in the MC get low (keep adding it), then when you are done you close the screw farthest from the MC first then work your way to the closest one. It does take a bunch of fluid to do this, but it works great. I bled my buggy (100% new system) using the one man bleeder pump and gravity bleeding and my brakes work great. My buggy even has a cutting brake (which can be a PITA to bleed) which rises back up to almost the same level as the MC (about 1" lower is all). I did use synthetic fluid which I have heard is easier to bleed but I have used these same methods on tons of different vehicles and swaps.

 

[PierCed_3]

Honestly, save yourself the trouble and take it to a shop. I know Big-O has some good equipment for pressure bleeding. It took them 2 large containers of Brake fluid to bleed mine . It's worth it, not just for the time you won't spend bleeding your brakes but also for the peice of mind that it is going to work.

That's my recommendation.

Andrew