Hello!
I'm having some trouble with my brakes.
I lost pedal pressure all of a sudden on a trip. I've tried diagnosing as best I can but still can't seem to find what is wrong.
I've got almost no pedal pressure at brake pedal, a little but not much. Pedal goes way too low as well, much different from when I left on trip.
I was about 3/4 to my destination. I stopped at a gas station after I noticed problem. At bottom of giant hill too so glad they're still working a little, it was scary. Brake fluid was low but I couldn't find anything wet on truck. Lower than it should be for pad wear I think. I haven't check it in long time tho so I'm not sure how much was in there at start of trip tbh. I filled it at gas station and continued on with trip.
When I arrived at destination I put rear on jack stands and noticed my self adjuster on drivers side was disconnected. I'm thinking it got stuck, but I've never had that happen before. Was expecting to find a broke spring but everything looked ok so I reinstalled and it seems to be working. I can adjust with screwdriver. Don't want to take truck on road so I backed up a few times in driveway and it still seems ok.

This is what I've done so far.

• Looked for leaks everywhere, including taking tires and rear drums off
• I bleed all the brakes but didn't find any air, just a couple tiny bubbles at most
• Aadjusted back breaks, the one that fell off and tightened the other rear but it seem ok
• Back breaks seem to engage, as far as I can't spin tire by hand with someone pushing pedal down
• Removed my MC for inspection, on bench with ports blocked I can push in cylinder about 1/8 inch but seems to hold pressure fine
• Reinstalled in van and tried each line separate, front works fine but when I connect to back... that's when I got no pressure and too much travel

So far there hasn't been any noticeable fluid loss.
I just can't figure out where the fluids going to the back with pedal to floor? My back brakes don't use flex hose really. There's one to the T but it looks ok, under pressure no bulges or leaks.
Not sure what to do next, I suspect the wheel cylinders but I'm not sure how to test that really.
Never had a wheel cylinder fail like that either, mine have always just started leaking when they go.

Thanks for reading my thread!

 

What fell off? If a shoe fell off the cylinder can easily overextend and it may not be obvious with the rubber boot covering the piston.

 

Thanks for reply,

The self-adjuster fell off, I didn't know it on the road. It looked like self adjuster didn't adjust and the gap to hold it in got too big.
At first I did suspect a stuck pad or shoe, so I felt all four tires many times, at gas station were I added fluid, and then stopped a few times along the rest of trip. Nothing was hot tho.

I'm going to take tires off tonight and try to take better look a wheel cylinders.

 

I know this seems silly, but make sure you check the soft lines going to the rear axle. I had a good leak on a 81 bronco that was above the transmission and where it was leaking was already wet from other oil leaks

 

Thanks man!
I've check that a bunch of times and it's bone dry.
It fells like there should be giant bulge or something, I got my neighbor to press breaks and I've checked every line but they all look good.

I did find a problem with self adjusters, pass side fell off. Tonight I found the self adjuster on drivers side is not engaging, and the E brake doesn't work on that side.
I'm thinking the stuck cable is causing a issue, but Its been stuck for years so probably not the problem. I'm going to get that free tonight if I can.
I'm trying to get lube on it and I think it'll work.

 

If the adjuster falls out the spring will pull the shoes together, not apart
If you now have the rear brakes assembled correctly and still have a low pedal
Bleed the master cylinder, and all 4 brakes again, start with a good gravity bleed for several minutes in case there is air trapped up the line from the bleed screws
I use a brake pedal depressor, when I am working by myself

 

I think I got a problem with self adjusters for sure.
The passenger side is the one that fell off. It got chewed up a little floating around in drum so I filed it smooth and reinstalled. I thought I adjusted it enough but maybe I didn't tighten enough? So last night I readjusted it, then took a look at drivers side and it's not good. The metal plate that holds the self adjuster wheel is not connected right. I'm starting to think that's the problem. I'm not sure why, it sort of sits out just a little to far for it to catch wheel. That's also the side my parking break froze so if I pull up on the cable in there the plate connects like it's suppose too.
I don't think it's a air problem, feels like broken line, or too much travel in this case.
I plugged the mc and it's tight, and if I just connect front still tight. But when I connect the rear line... that's when pedal goes to floor.
Good news is since working on self adjusters it's seemed to have gotten better, still not good height but no longer going to floor.
I don't have a way to get new parking cable where I'm at right now, sort of out in middle of no where. So I put a clamp on side that works, so it won't engage. Then pushed on parking break as hard as I can so it's pulling the frozen side, then soaked the whole thing in pb and that's how it sits now.
I'd like to get that cable out to work on it but not sure how, got to look into that later today.

 

Might want to get new rear cables and reinstall the rear brakes (again)
When those rear E brake cables stick, it wreaks havoc on the adjustment and the operation of the brakes as the duo servo action takes place and the shoes pivot on the upper pin
When those shoes pivot, it wants to make the adjuster fall out
Then
If you get them adjusted up enough, the adjuster will not fall out but the brakes will then grab
If you take a big pry bar and force the E brale lever back, you can then adjust the brakes and use them as long as you do not hit the E brake again
To get the cable out, remove the shoes and push the 3 tabs back or better yet break them off and then the cable pulls out for replacement
If you use a small hose clamp you can sometimes get the cables out without breaking the tabs off the cables
Soaking them in a solvent tank for a week or two can sometimes free them up
They used to be cheap at Autozone, like 26 bucks apiece, so I just break the tabs abnd replace them

 

If you think there is air in the syatem bleed the brakes
To start with, just
Gravity bleed each wheel and watch for bubbles
If you see any bubbles, start over by bleeding the master cylinder first then each wheel with an assistant or a brake pedal depressor
However,
Rear shoes that are out of adjustment is the main cause of low brake pedal

 

Yeah I think this parking brake cable is the source of problems for adjusters, it's stuck open tho. Just cant get the self-adjuster to sit right like you mentioned.
I like the idea of using hose clamp, I'll try that.
I need to travel soon so I'm trying to avoid ordering any parts if I can for now.
I bleed brakes but didn't find any air so I think I'm good on that.
Thanks for the help!

 

Update on brakes
My problems turned out to be issues with rear self-adjusters due to a bad parking break cable.
I wasn't able to change cable out yet, but I was able to get both adjusters working and my pedal returned to normal (satisfactory).
I noticed my MC was just a little wet by rear seal when I inspected on bench.
So next I bleed a new one then installed, then flushed all the lines.
After that brakes feel even better, more so than the whole time I've owned this van.

I'm speaking of a 1978 E-150 btw.