Can someone give me direction on a problem with the brakes?I replaced a rotor and pads and also both calipers.I bled the brakes and they were fine.Started to back up and they were no brakes.There is a manifold that sits between the master cylinder and what I believe to be the abs.I can get fluid through all the lines except the one that goes to the abs.I took the manifold off and cleaned it out making sure that all the holes weren't clogged.I put it back on and there still wasn't any brake fluuid coming through it.Does any one have any ideas.Thanks for the help in advance.

 

Hi Lkonig:

Welcome to our FTE forum

That manifold is the proportioning valve, and it'll cutoff fluid flow to the rear should there be a massive leak in the rear brake circuit. If you are not careful in bleeding the rear brakes, it'll think you have a bad leak and it'll shut off the flow as it's designed to do.

 

may have to force proportioning valve back into pass position, may be stuck in shutoff position from corrosion/dirt/water/goop
there is a threaded cap on one end...remove carefully, high pressure spring inside with long piston/valve....remove and clean out...replace....careful with the small rubber plug in end-do NOT remove plug
may have the combination valve with builtin ABS switch....black plastic screwed in unit at one end...remove switch and clean interior, switch and light spring of corrosion

did you release caliper bleeder prior to forcing brake piston back into caliper....if not, forces old water/brake fluid goop corrosion dirt back into system

use a small rubber tube that will fit over the bleeder screw tightly , other end into a partially filled container of brake fluid....use slow pedal pressure and never to floor bottoming pedal....
do a full bleed starting at longest RR...bleed each until clear new fluid comes out....run at least a full quart thru system....keep the master cyl. reserv. full, never let it drop more than 1/2

are the front brakes working and holding vehicle....80% of brake force on Aero is the front disc brakes

always replace rotors and pads on both sides at same time to maintain even braking and no steer pulling during braking....can end up with one side lock up.....
different brands/manuf.'s of rotors have different friction coefficient

 

I replaced both calipers on the front so no force was ussed to put them on the vehicle.I have also taken the valve apart and cleaned it.Therre was some corrosion in there.After I cleaned it there still wasn't any brake fluid coming through that one hole

 

time to replace combination/proportioning valve...plugged with corrosion
may try compressed air to reverse blow out corrosion particles...very small orifice in valve

 

Do you think I could get a good one at the junkyard or should I buy a new one?

 

If you have no brakes front or rear, you have a bad master cylinder, assuming that the system has fluid and no air and is blead which it sounds like it is. It is impossible to lose both halves of the system unless it is the master cylinder. It is the only commonality between the two systems. The proportioning valve can not do this.

Ken

 

Not true, if the RABS valve fails you will have no brakes because the pressure gets bled off till the MC is starved for fluid, happened in our van, started with mushy brakes then quickly had no brakes. MC turned out to be fine, but the RABS valve got stuck open.

 

Yes! Khan's and 96-4WDR's advices helped me to solve problem with proportional valve.... I had to take it appart, clean it inside, replace 2 seals and it works fine now....

LKonog! I had the same symptoms!

 

Khanty,

If the rabs "bled off" fluid to starve master cylinder, where did the fluid go. If to the accumulator, it would be pressurized and still stop[ the truck. Main point is the r in rabs, rear. the front brakes would be unaffected.

Remember, with a tandem cylinder in working condition, you could cut a front or rear line and the remaining half will stop the truck albeit with more pedal travel.

Ken

 

I wasn't driveing at the time the brakes went out, but my sister fist tried pumping them and it had no effect, so she pulled of the road into the snow and let it coast to a stop. When we had it serviced, the MC was fine, the only part they replaced was the RABS valve. We latter had the MC replaced because the diaphram that grants you power brakes had some oily film on it, but the MC still worked just fine. I don't know al the details of how the brakeing system works, but I do know what fixed it.

 

Be glad you wernt trying to figure out ANTI LOCK BRAKES

 

This forum has helped me alot with a similar problem I am having.. I am working on an 87ish ford areostar van. I've got NO pressure to the rear brakes. the front one work fine, great in fact... but not a single drip to the rear.... I've taken apart the proportioning valve and cleaned it out(like new IMO) and put it back together the same way..... when I install it I still have great pressure to the front but not a drip again the to the rear.... whats goin on?

I've take off the rear line(disconected it from the proportioning valve on the bottom) and when my asst. pumps the breaks I'm getting only drips from the bottom of the valve.... if I do the same to the front line(on the valve) it squits like crazy..... why am I not getting pressure in the valve to counter that spring in there to get fluid to the rears?


Thanks in advance!