jeepmjga Posted April 14, 2021 Author Share Posted April 14, 2021 Well the new stuff should be here by the weekend so I will let everyone know the outcome. After the new mc and booster that should be all the parts of the system except new distro blocks and height valve so hopefully this is it. Thanks for everyones input so far! Link to comment Share on other sites More sharing options...
derf Posted April 14, 2021 Share Posted April 14, 2021 I would change the process slightly. When bleeding the rear valve and you have the front open, depress the pedal and hold it. Then close both valves before letting up. Repeat as necessary. Link to comment Share on other sites More sharing options...
jeepmjga Posted April 15, 2021 Author Share Posted April 15, 2021 So just an update for anyone following. I vacuum bled the entire system today, then re-bled it again using standard procedure (no vacuum). Definitely no air in the system, the pedal builds pressure and stays steady when the truck is off and the brakes are holding, as in I can't move the rotors/drums when the pedal is pressed in while the truck is off. Then when I start it, pedal goes straight to the floor. Fairly certain there is some sort of failure in the booster chambers somewhere. Will hopefully have some better news on Saturday after I replace the MC/booster. Link to comment Share on other sites More sharing options...
derf Posted April 15, 2021 Share Posted April 15, 2021 Makes sense. Link to comment Share on other sites More sharing options...
jeepmjga Posted April 18, 2021 Author Share Posted April 18, 2021 Well, I am at a loss here. Installed the new m/c and booster today. Bench bled the master, installed everything then bled the entire system just like before, accounting for the prop valve and everything and STILL the pedal falls straight to the f-in floor when I turn the truck on. The booster is working and there is good vacuum to it. Something I did notice is that when I push the pedal all the way to the floor the motor almost wants to stall out like there is some sort of weird vacuum issue going on. Also, maybe the old heads can give me some advice here, when I go to activate the bypass valve by keeping a front bleeder open and pressing the pedal, it seems to me like its not working correctly because when I go to bleed the rear brakes fluid is just pumping out of the open bleeder. I was under the impression that when the bypass valve activates it diverts all braking to the rear wheels because its simulating a front brake failure. Am I wrong here or is there something I'm not doing right? I guess if I can't figure this out my next step is going to be to delete the height prop valve and go with a different setup, which is what I was trying to avoid. Anyone got any ideas? Also frustrating because this is the last thing keeping me from driving it. Link to comment Share on other sites More sharing options...
fiatslug87 Posted April 18, 2021 Share Posted April 18, 2021 Are you using a new check valve at the booster, has it tested good? Link to comment Share on other sites More sharing options...
scaleless Posted April 18, 2021 Share Posted April 18, 2021 I was under the impression that to activate the bypass valve you needed to open the front bleeder, then press the pedal, then start bleeding the rear brakes. This is because the bypass valve activates when there is an extreme pressure differential between the front and rear lines. Having both open before you press the pedal does not cause a pressure differential. I'm certainly no expert, though, so it would be great if someone else chimed in. Link to comment Share on other sites More sharing options...
zomeizter Posted April 18, 2021 Share Posted April 18, 2021 I went through this before and turned out to be air in a new master cylinder, I thought I had bench bled it well but air bubbles kept showing up in the reservoir. I spent about an hour slowly depressing the brake pedal and slowly releasing, until no more bubbles were present, solid pedal after that. New MCs are sometimes defective out of the box... Link to comment Share on other sites More sharing options...
jeepmjga Posted April 18, 2021 Author Share Posted April 18, 2021 10 minutes ago, fiatslug87 said: Are you using a new check valve at the booster, has it tested good? Yes, its a new booster with new check valve. 7 minutes ago, scaleless said: I was under the impression that to activate the bypass valve you needed to open the front bleeder, then press the pedal, then start bleeding the rear brakes. This is because the bypass valve activates when there is an extreme pressure differential between the front and rear lines. Having both open before you press the pedal does not cause a pressure differential. I'm certainly no expert, though, so it would be great if someone else chimed in. Thats how I understood it. When I opened the front bleeder everything else was still closed, then I went to pump pedal to bleed rears and fluid is still just pumping out of the open front bleeder, which makes me think the bypass is not activating? 4 minutes ago, zomeizter said: I went through this before and turned out to be air in a new master cylinder, I thought I had bench bled it well but air bubbles kept showing up in the reservoir. I spent about an hour slowly depressing the brake pedal and slowly releasing, until no more bubbles were present, solid pedal after that. New MCs are sometimes defective out of the box... I will try that tomorrow, so you just slowly pumped and released the pedal while it was already installed and truck off? Link to comment Share on other sites More sharing options...
zomeizter Posted April 18, 2021 Share Posted April 18, 2021 3 minutes ago, jeepmjga said: Yes, its a new booster with new check valve. Thats how I understood it. When I opened the front bleeder everything else was still closed, then I went to pump pedal to bleed rears and fluid is still just pumping out of the open front bleeder, which makes me think the bypass is not activating? I will try that tomorrow, so you just slowly pumped and released the pedal while it was already installed and truck off? I actually bench bled it on the booster, truck brake lines off and plastic fittings and clear hoses on the MC, those air bubbles seemed endless! Link to comment Share on other sites More sharing options...
scaleless Posted April 18, 2021 Share Posted April 18, 2021 7 minutes ago, jeepmjga said: which makes me think the bypass is not activating I have not experience but have heard of proportioning valves getting internally seized, which kinda sounds like what you're describing. Link to comment Share on other sites More sharing options...
Pete M Posted April 18, 2021 Share Posted April 18, 2021 you would not be the first guy to receive a DOA booster. the front combo valve that Eagle sliced open turned out to not be fully drilled at the emergency bypass port. Link to comment Share on other sites More sharing options...
jeepmjga Posted April 22, 2021 Author Share Posted April 22, 2021 Well, first off thanks to all the help here. Secondly, I'm a dummy. The calipers were actually on the wrong sides, I guess I misunderstood what "bleeders on top" meant. They way I had them, the bleeders were above the brake line, it never dawned on me that they should be the other way until today. Live and learn I suppose! I ended up going with a Wilwood prop valve and deleting the rear height valve anyway after making that nifty adjustable set up. I guess at least now everything in the system is new except the lines Pics in my build thread, thanks again for all the suggestions and from now on going to always step back for a sec when I run into another problem. Link to comment Share on other sites More sharing options...
scaleless Posted April 22, 2021 Share Posted April 22, 2021 Ha, don't worry, as far as dumb things we all do go, that's one of the least dumb! You'll need to step up your dunce game if you want to roll with the rest of us. Link to comment Share on other sites More sharing options...
derf Posted April 22, 2021 Share Posted April 22, 2021 Yep. Been there. Done that. Welcome to the club. Link to comment Share on other sites More sharing options...
Pete M Posted April 22, 2021 Share Posted April 22, 2021 I swear I've only done it once. I think. Link to comment Share on other sites More sharing options...
derf Posted April 22, 2021 Share Posted April 22, 2021 11 minutes ago, Pete M said: I swear I've only done it once. I think. Some of us have to stick our fingers in the light socket a couple of times before we learn. Link to comment Share on other sites More sharing options...
mjeff87 Posted April 22, 2021 Share Posted April 22, 2021 We're not laughing at you, we're laughing WITH you...... That was one of the earliest mistakes I ever made while wrenching on mine. Glad you got 'er fixed! Link to comment Share on other sites More sharing options...
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