Yet another update!

I gravity bleed the brakes, fluid come out of the fronts, nothing from the back brakes..
Cleaned the bleeders in the back that were not blocked.

Was able to get some fluid out of the drivers side rear.
Nothing from the passenger side rear at all, had my son help me for about 30 minutes.

Brake feel a little firm when engine is off, when running the brakes go to the floor.

Going to see if i can borrow a pressure bleed system (Is that the correct name?)

Still would love to know why a MC for a 20 year vehicle is over $200.

Thanks in Advance

 

probably crushed or plugged back brake line
plugged at the connection 3 way mounted on the diff housing
never get the brake line nuts off after 20 years.

MC prices
shop one of FTEs sponsor RockAuto

WAGNER Part # R114075 More Info {Reman} [Wholesaler Closeout -- 30 Day Warranty] (Only 1 Remaining)

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DORMAN Part # M39628 More Info {First Stop #E79Z-2140-A}
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RAYBESTOS Part # MC39628 More Info {Professional Grade; Bore Size=15/16" Number of Ports=2 Primary Outlet Size=9/16x18 Secondary Outlet Size=7/16x24}

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ACDELCO Part # 18M346 More Info {#18030588}
CYLINDER,BRK MAS DURASTOP; WITH POWER BRAKES; 15/16 CYLINDER BORE
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Thanks for the reply and the info on the MC..

wow they are cheap compared to the prices i was getting.

The only problem is that my MC looks like the one in the picture at the beginning of this thread.. The big one.
The power booster is that big 6 inch thick one! and it is from a 1991.

This van has always been an issue when getting parts!!!!!!!

What is so weird is that i was getting brake fluid out of the Pass. side rear brake before!

 

try blowing the rear lines out back to front with air compressor. remove both ends so the garbage doesn't go into the RABS system or MC. wear eye protection, don't ask how i know

this one? 91 Aero there was a MC change upgrade in 91. occurred in 2-91 production date. have to visually check to order correct MC. depends on MC bore size 15/16" or 1 1/16"

the price went up because of the addition of a proportioning/combination valve which is included with new replacements.



yes more money. buy the rebuilt unit RockAuto.com
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1991 FORD AEROSTAR 4.0L 245cid V6 MFI (X) OHV : Brake/Wheel Hub : Master Cylinder Price Core Total Advice
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RAYBESTOS Part # MC390216 More Info {Professional Grade; Bore Size=1 1/16" Number of Ports=2 Primary Outlet Size=3/8x24 Secondary Outlet Size=7/16x24 #MC39880}
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CYLINDER,BRK MAS DURASTOP; 1ST DESIGN; BEFORE 2/91; w/POWER BRAKES; EXTENDED LENGTH, 15/16IN CYL BORE

 

Thanks guys for the info.

I don't have compressed air, but let me see if i can barrow a Compressor.

This one looks exactly like mine.

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DORMAN Part # M39881 More Info {First Stop #F09Z-2140-D, F19Z-2140-B}
w/Power Brakes; Bore = 15/16"; OE Factory Design; Extended Length

But it ain't no $69.79!! more like $226.79

 

Oh No!! I am back again!!!

I have been very busy and have had no time to work on the van lately.
but had some time last night!!

Yet another odd question:

I bought a brake bleed vacuum Pump.

• Check fluid in MC.

• Bleeders are clear, nothing blocking them

Started with Passenger rear:Place hose on bleeder
Pump up vacuum pump
Loosen bleeder.
repeat.
I got some fluid out, not alot, then i did it for at least 15 times and nothing just air.

Went to Drivers side Rear.
Got some fluid out.
Then the vacuum pump would not release the vac.
I took it off released the vacuum, put it back on the bleeder.
Pumped it up, loosen bleeder, still not releasing vacuum

I took the rear wheels off , maybe it is the wheel cylinders.
They were dry..

Any Ideas????

Thanks

 

Most of the time when you're pumping vacuum to the bleeder screws, they will leak air from around their threads. I wrap a little bit of teflon tape around the threads to seal them off. Then when you pump down the vacuum, all that negative pressure is applied to the line to more effectively suck out the old fluid.

 

Thanks for the advice on the Passenger side bleeder, never crossed my mind to do that. Guess air could leak out the threads. it not like I am turning a few turns, Lucky if I am turning it 1/4 turn before vacuum is released.

Any thoughts on the Drivers side bleeder? I tried it again after posting my last message, it is acting like there is a blockage!! The bleeder hole is clear, no leak on the wheel cylinder, even tried pumping the brakes and doing it again..

Done many brake jobs just like this before on different vehicles.

Love this van, seriously!! every time something happens to it, like a mystery to get it running again..

 

There can be crud blocking the line. It's usually rust that forms inside.

I once tried to bleed a caliper that did nothing even after I removed the screw. I was pushing the brake pedal to bleed at the time, and this caliper felt like the bleeder was still closed. I eventually pushed very hard, it did give way. I found a lot of rusty fluid all over the place, but never did find what was clogging the hole. After that, I was able to bleed normally.

So you might try removing the screw and pump the pedal to see if you can get anything out of it.

 

Thanks for the advice.. I will remove the bleeder and try that..

The brakes have nothing there, goes to the floor, when i gravity feed the brakes I had some firmness...but then then I have not working on the van in a while.

Will try that tonight... thanks for helping..

 

No pressure on the pedal? That sounds like you got air into the system. That could make it difficult to fully bleed the system. I've never done it before, but I think it's pretty involved. At least make sure you don't let the fluid in the reservoir get too low as you're either vacuuming it out the back or pumping by the pedal.

 

Thought of that last night and that is what it sounds like to me Air got in there some how.

This vehicle has been down for so long now I am having trouble remembering what has been done..

It sat for a while with out the power booster / MC on the vehicle.
( had trouble locating a power booster )

Hoping to spend some time tonight on it...

 

Wow, it's probably got air in the RABS control valve then. I saw the procedure for bleeding that on this forum before, but i can't find it now. Perhaps that should be a sticky?

I mentioned this before, but I don't know if there is a device to do it. Most brake bleeding involve pushing fluid DOWN from the MC to the bleed holes, which are always below the MC. I would like to bleed the brakes by first pumping out the old fluid (until the stuff coming out the bleed screws is clear), then pump fresh fluid up into the system from the bleed screws. Since air is lighter than brake fluid, this will help push trapped air bubbles up and out of the system. I do this on my bicycles with disc brakes.

 

Thanks:
I did a Google search on " bleeding RABS control valve "

and the first hit was right back to this site!!!!!

Link

I hope mine is not failed!!!


Where is the RABS (box or whatever it is called) located??


I remembered when i gravity bleed the brakes, fluid dripped out of the fronts without a problem, but nothing from the rears!!!

 

I think it's mounted on the firewall right under the MC. Just follow the brake line leading to the rear brakes.