'66 Cj5 Tux Resto-mod

If the master cylinder didn't drain completely, you probably don't need to bench bleed it. If it did drain completely you should start there.

Another member PM'ed me with an observation about your brake plumbing (He didn't want to add confusion to the current issues.)

Looking at these pictures:




You have the circuits hooked up backwards on the master cylinder. The larger reservoir always goes to the front brakes. Counter-intuitively it's typically the rear reservoir that powers the front brakes. The front brakes need the larger reservoir because the pistons are bigger and the fronts typically wear faster. As the pads wear, the resting position of the caliper pistons gets closer to the disks. Additional fluid from the reservoir needs to take up the space. More fluid is required for the fronts as they wear than the rears.

NOTE: The should be fixed but it has no bearing on your current bleeding issues. It does mean you get to bleed the rears again though.

 

Well shucks.

 

You wouldn't want to run out of things to do would you?

 

At this rate I’m running out of paper for my to do list!

Please thank whoever it was that pointed that out to you - it clearly states that in the directions and I don’t know how I missed it.

For the record, publicly, I have zero shame about doing anything wrong… The whole reason I’m doing this build is to learn and I really really really really really appreciate whoever it is that pointed that out so that I can fix it and be safe.

 

Since you will be working on the proportioning valve, to be safe, replace the 2 mounting bolts. They are each about 1/4" to 3/8" too short in length. Safe practices call for at least 2 threads exposed beyond the nut.

 

X2, I didn't like that either.

 

Good eyes guys - those pics above are old and from when I was roughing everything in and just had it hanging there. I permanently (I hope) mounted it with longer flanged GR8 bolts and toplock flanged nuts when I filled the cylinder and lines.

 

You guys have some sharp eyes. For some reason, new empty systems are just a bastard to get going. But I'm here to cheer you up, Grant. Just imagine you were paying someone 100 bucks an hour shop rate to bleed your brakes.

 

Indeed!

 

OK what do you guys think about this idea? I dug in the “brakes” parts box this AM before work and found that I had at one point thought about doing stainless Earl’s flex lines from the MC to the PV, before I bought flaring and bending tools.

Given that the body is on and bolted, would these work instead of making new hard lines? The adapters are AN3 to inverted 3/8” flare.

 

They will work but it's recommended to only use hose where you need flex. Even stainless braided hose is more flexible than the hard lines. The more hose you have the softer the pedal will be.

In practice though, I doubt you could tell the difference with these short high quality lines and they are probably fine to use. The stainless sleeves on those act like buzz saws when things vibrate, so make sure the are routed to not rub on anything.

 

Thanks. I have just enough hard tube left to try for one more go, so perhaps I'll see if I can manage that first and keep these in my back pocket.

 

Next question from the to-do list: Does this bend look right for the alternator bracket? It was bent like this on the Jeep when I got it - I did not bend it to put on this aftermarket alternator.

I'm also not 100% sure the pulleys are lined up correctly either.

The mounting post on the Powermaster alternator is smaller than the OEM or Delco ones so I had to add a spacer, and I still need to add some shims to it to suck up another .010" or so. Don't want to break another bracket ear!

 

As I recall, the brackets have a slight bend from the factory.

You need to make sure the pulleys line up and the bracket will end up where it needs to be. Put a belt on it, it's usually pretty obvious if the alignment is off when looking down the length of the belt towards a pulley.

 

Ok so having never done this before (shocking I know!) I want to try to make a game plan before I head out into the garage. Is there any way I can try to keep the master cylinder from draining when I disconnect the lines between the PV and he MC? If I am ready with the bench bleed hoses, and they are already up into the clip on the wall in the tank between the reservoirs, if I try to thread them into the holes they should keep the fluid from draining right? And I'll need new copper crush washers on the banjo bolts that go into the MC line exits so I'll try to have those on hand. I suspect I might be able to salvage the longer of the two lines and move it to the front...might even be able to cut it and make a new flare. BUt first I want to try and get it all off and keep the fluid in the tank.

 

Well…still in brake bleeding hell. really banging my head on the wall all day, just wish I had another set of hands that knows what’s going on to help.

I managed to swap the front/rear lines to the MC/PV, got lucky there and was able to finesse the hard lines into the opposite holes.

Tightened everything back up and got to bleeding. I invested in a vacuum pump bleeder, but for whatever reason I just can’t get it to pull fluid. So since I had to go to reno anyway, I got a vacuum can compressed air bleeder. That also won’t suck fluid through any of the bleeders. It sucks what looks like a trickle of foam when left on and running for five minutes at 100psi but no steady stream of fluid. I just don’t understand why fluid won’t drain out of the master cylinder. Could it be the way the PV is set?

I did manage to have my wife come out and pump the pedal so I could bleed the fronts the old fashioned way, and that worked.

but I can’t get any fluid to come through the rears either with the hand pump or the compressed air bleeder. I even had the wife push the pedal with the bleeder screw removed and the pedal is super hard and nothing come out.

So what to try next? Do I just completely dissssemble every fitting, drain everything, bench bleed the master, and try from there?

Is the issue in any way related to MC push rod length?

 

Have someone pump the brake pedal and hold like you would to bleed the brakes. Then go one fitting at a time and lossen it to see if any fluid comes out. Start at the master and work your way to the calipers. If you dont have fluid at the master cylinder ports you might have to take it out and bench bleed it again. Did you remove the plugs from the master cylinder ports that the lines attach to? I have never had any luck with the vacuum bleeders, i use speed bleeder fittings on the calipers and those work great for one person bleeding.

BTW. The arm on my alternator braket bolts onto the back side of the alternator ear.

 

I got speed bleeders for the rears but neither vacuum pump would pull through them…

thx for the tip on the alternator ear.

What are the possible options for why fluid won’t come out the rears if both bleeder screws are completely open and the pedal is still super stiff?

 

I went and looked at the alternator brackets for the 225 I have on the engine stand and the 350 in the '71 and they are indeed on the back side of the alternator tab.

As for the brakes, it seems like the problem has followed the circuit on the master cylinder so it seems like a master cylinder issue?

There are only two things I can think of that would prevent fluid flow from the reservoir:

1. The master cylinder piston isn't returning for enough to open the intake/return port. Now that the body is on, make sure there is a little slop in the master cylinder push rod when the brakes aren't applied.
2. There is some sort of blockage. You would likely need to pull the master cylinder out to check this.

As supertrooper said, you should start working though it piece-by-piece starting at the master cylinder fittings to see if you can find where the blockage is. But do make sure the master cylinder piston is returning all the way before doing much more.

 

Yeah I’ll check that first for sure. When I bled the system successfully before, the body was off. I suspect the pushrod is too long. I also have 3/4" urethane body mount pucks between the body and the frame if that is a factor.

Looking at this and thinking about what is going on:


Good explainer here:
https://shop.wilwood.com/blogs/news/troubleshooting-no-fluid-pressure-at-the-rear-brakes

And that the problem followed the circuit I moved, I bet the root cause of all this is that the piston isn't going back far enough.