This is for my 86 f-250
Accidentally ran the rear brake reservoir out of fluid the other day.
So I'm vacuum bleeding the rear brakes and I still am not getting pedal back.
When bleeding I'm not seeing a consistent flow of fluid but it sure seems like it should have pulled any air out by now.
I filled the reservoir several times while doing this. Maybe I need to go at it longer?
From what I can tell the proportion valve is self centering and I don't need to push or pull a pin and I don't see one anyway.
But maybe I'm wrong on this.
I should see a steady stream of fluid when I'm pulling a vacuum correct?
Maybe I blew a wheel cylinder I'm not sure but that will be the next thing I check, I didn't see any wet spots anywhere
I was thinking maybe the fluid went out the top of the cap but I don't think all of it would have went out that way?
Again didn't see much wetness under the master cylinder if that was the case.
Fluid had to go someplace though..

edited to add: the rear passenger tire has fluid coming out when cracking the bleeder, the driver side nothing yet.
I'm just going to keep pulling vacuum on it for the time being. Even if that wheel cylinder blew, I think I'd get a good flow of fluid out of the bleeder?

 

Ok lets back up a little and look at what you said here "Accidentally ran the rear brake reservoir out of fluid the other day."
This is the large one and is not for the rear brakes it is for the front disc brakes.

If you did not find any leaks from the master to the front wheels the fluid is leaking into the booster.
Replace the master and bench bleed it before you bolt it up.

As for vacuum bleeding you using one of them Mighty Vac hand pump things?
Yea they work like crap to start with. On the side you are not getting fluid if you pull the bleeder out does the fluid come out then?
A lot of times the bleeders get plugged. You can run a small drill bit down it to open it up and get it working again.
Dave ----

 

No I didn't mean the rear master cylinder reservoir, I meant the rear brake reservoir, which is the front reservoir on the master cylinder.
Sorry for not being more clear, I just assumed when I said rear brake reservoir... well yea anyway..
I am using a cheapy harbor freight bleeder. It's worked in the past and iirc when I did use it, I would get a hose full of fluid vs what I am seeing now.
I have pulled the bleeders completely out and no fluid comes out. I even stuck the rubber nipple that goes over the bleeder into the hole
and tried was able to pull fluid out but still wouldn't come out on its own.
I replaced 1 bleeder fwiw, the other one seems to be ok as well. I checked by hooking the bleeder nipple up to, pulled a vacuum and watched for my glove to get sucked into the orifice.
I called it a night, I probably went thru 16oz of brake fluid already so I left the bleeders cracked so maybe it will gravity bleed overnight.

If the booster is bad, shouldn't it be sucking fluid out of both master cylinder reservoirs and not just one?

 

If the booster was pulling fluid from the master it would only pull it from the reservoir closes to the booster.
You see that divider between the 2 reservoirs? There is no way for fluid to get from the front to the rear.
Dave ----

 

well it isn't the booster than as the rear reservoir fluid level has not moved/changed any.
It's weird, I don't recall having this kind of issue before.

 

The proportioning valve, as I understand it, will shuttle to isolate the low pressure circuit. So if you ran the rear dry, it is possible the valve is still shuttled to isolate that circuit?

Centering procedure in my manual is to step on the pedal. Have you tried pumping the pedal since you’ve refilled the master?

I have a Bronco and the manual says to pull the proportioning valve pin out of the housing to bleed the fronts. It does not mention any specific pin position to bleed the rears.

 

Yes I did follow the procedure for centering.
On my 79 you have to pull the pin out to bleed but that is a f150, I thought the f250's (maybe it was only for those years as well) needed it pushed in but I can't find it in my manual now and all it says
is it's self centering. Anyway I don't see a pin on my 86's valve like my 79 has. But definitely thought it might be something to do with that valve.

 

Please read this short thread:

https://www.ford-trucks.com/forums/1...sues-help.html


Specifically, please see post #4 for my theory on how the proportioning valve interferes with brake bleeding, and how to get around that. I suspect that is the problem you are encountering.

FWIW, I've given up on vacuum bleeding. The results were always fair at best.

 

good link! I'm just by myself so I don't have any other option besides gravity and vacuum. Still trying to keep this social distance thing happening.
I have a feeling it's more in the wheel cylinders especially seeing what Franklin2 posted there but I'll give the line between the MC and valve a crack and see what I can get.

 

You're never alone. You've always got the UPS delivery guy!

Send away for the pressure bleeder:



Or make Dave's homemade version. Either way, you'll then need to sit on your hands to avoid slapping yourself, wondering why you didn't get one sooner.

 

I always thought they were the same thing honestly.
The gravity bled worked somewhat, the reservoir went down, saw fluid dripping out of the bleeders but still the pedal is the same..
Took the one wheel off where I didn't seem to get much fluid from and the wheel cylinder is a bit damp but nothing drastic. the backing plate wasn't soaked just
the rubbers looked damp. shoes were dry, looked good as well as the drum but a bit rusty..
Looks like I need to rebuild or buy new cylinders at this junction. If it was the valve I don't know if the reservoir would have dropped as much as it did?

 

From my experience, rebuilding is waste of time. Any time the seals had failed, the bores were also pitted. Honing the bores is like arguing on the internet. You might think it changes something, but not really.

Reassemble the freshly honed cylinders with new seals, reinstall them, and do a full bleed. The next step is to drive to the parts store for new wheel cylinders because your rebuilds are still leaking. I like to cut out those intermediate steps nowadays, and just go new. Not much price difference, especially considering the gas for a second trip to the parts store.

 

absolutely correct, after I saw the price for new cylinders, I scrapped the idea of rebuilding.
It really is only a couple dollars more vs a rebuild kit, the honing tool is more than both new cylinders as well which I would have to get.

 

I don't know how you are going to do it, but once you get the new wheel cylinders in place, if you still have trouble bleeding it you are going to have to beg someone to come over and press the brake pedal for you.

Did you ever say what caused the fluid loss? I missed it if you did, but that could be part of the story we are missing.

And once you get everything back together, make sure you manually adjust the brake shoes out till you can't turn the drum, and then turn them back till there is slight rubbing, but you can turn the drum. That will make sure your pedal is high. If you still have air in there it will be high but a little springy.

 

No I don't know what caused the fluid loss honestly, I did not see anything that would give a clue as to where it went.
I could see some of it going out the top but not as much as was missing. (wasn't wet either so I don't think any went that way)
I followed the lines down the rail and didn't see anything there, as mentioned above, backing plate was dry on both sides.
Yea I'm going have to get someone to come over, trying to avoid it since we are under stay at home orders here.
I'm going to replace most of the brake system, front to back and any lines that look questionable.
Working on filling my rockauto shopping cart.