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90 Bii rear driver wheel cylinder wont bleed

A4LD_Nghtme

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So I've officially finished rebuilding my passenger drum after replacing the siezed parking brake cable and so I began to bleed the brakes.

I bled the passenger wheel cylinder first and was able to get brake fluid to bleed through it. Upon cracking the bleed valve on the driver side wheel cylinder and attempting to bleed I got absolutely zero fluid pushed through at all.

Does anyone know why this may be happening? Is there a proportioning valve of sorts on the Bronco IIs that may possibly be my issue? Lines aren't leaking, kinked or broken
 


Uncle Gump

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Bleeder screw plugged... or steel line plugged.

There is no valve that will prevent flow to one side and not the other.
 

A4LD_Nghtme

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Bleeder screw plugged... or steel line plugged.

There is no valve that will prevent flow to one side and not the other.
Well I pulled the line off and sprayed through it with brake cleaner and it was flowing it through. however i wasnt even getting a leak from the center hydraulic line that feeds the two rear lines.

So I pulled off the passenger line even though it was having some fluid in it because I realized it was slow and when I removed it from the center feed line there was still zero fluid coming out of the open port. Just residual I had in the line and I was ready to plug the feed.

Any ideas?

I can replace the center hydraulic line with a Duralast 78172 really quick to see if that fixes the flow but I'm wondering if it's the RABS valve and what I got out of the passenger side was just residual. It seem like something is clogged somewhere further up from the drums. Nothing is broken.
 

dvdswan

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I would pull the bleeder screw out to be sure there was fluid in the wheel cylinder. If its empty they you will need to move up the line to find the clog. I think @Uncle Gump is on the right track. Something is clogged or plugged.

Remember, the BII is over 30 years old. Lots of road grime/dust/rain soaked parts, and that's if its never been offroad.
 

RonD

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Yes, could be the ABS valve, by-pass it

Or take off the OUT line from the ABS unit and see if fluid Gravity bleeds out, should be a steady flow from the master

Any time you open a bleeder, at any wheel, you should get Gravity bleed of fluid from the master, there are no valves from master to bleeder when brake pedal is up all the way
When you press brake pedal down the piston in the master cuts off the upper reservoir and applies pressure to the brake fluid in the brake lines
When brake pedal is back up then reservoir is reconnected and fluid is free to flow to any open bleeder

Proportioning "valve" just has smaller orifice(hole) for rear brake line, so less fluid will flow to the rear to try and prevent lock up of rear wheels
ABS cuts off flow to the rear momentarily(pulses) if axle lockup is seen
 
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Shran

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I'd crack the lines open where they go into the center hose and give the brake pedal a push - see if you get any fluid seeping out. If not, keep moving forward... check the hard line that the soft line is attached to, then the other end of that hard line at the ABS valve. I have seen those ABS valves fail in a variety of ways but your issue could be something else.
 

A4LD_Nghtme

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I would pull the bleeder screw out to be sure there was fluid in the wheel cylinder. If its empty they you will need to move up the line to find the clog. I think @Uncle Gump is on the right track. Something is clogged or plugged.

Remember, the BII is over 30 years old. Lots of road grime/dust/rain soaked parts, and that's if its never been offroad.
Ill run it back up the line and replace as I go as I've always done because I tried to account for the old gal being a bit too mature from the purchase get go.
Do you know if the RABS valve can get stuck/not allow fluid to the rear? This seems to be a possibility via mass internet searches but I am not certain of its entire function and or whether or not it acts like a proportioning valve.

EDIT: Sorry for not seeing the following two replies. My service in Placerville is really the pits. So I am out of order
 

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The RABS valve can do all sorts of weird crap. I had one that would slowly get stuck and lock up the rear brakes as you drove... another one had a very slow leak and I'd lose brake pressure but only on hills. That one took me forever to find because it wouldn't drip very much. I thought that the brakes just weren't bled enough.
 

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The flex hoses are known to internally collapse... both front and rear. With the age of the truck... I would replace all three.
 

A4LD_Nghtme

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I have an update!
My RABS valve had ZERO flow to the rear so I replaced it and was able to successfully bleed the rear. Yet is still have a problem with parking and antilock lights being illuminated but before that here's what else I've replaced along the way to get these brakes back.

I replaced both the passenger and driver side parking brake cables, the rear drums fully minus dustplate, the master cylinder, the rear brake hose that supports the two rear brake lines, and the ABS Sensor at the rear diff. I also cleared/cleaned the 4 individual rear brake lines(2 in rear for each wheel, 1 main from rabs valve to rear hose, and 1 from master cylinder to valve) since I took the system apart before I bled the brakes and those lines are still perfect.

Fluid level is perfect and the brakes now work better than ever, yet I still have a parking brake light on and the yellow rear antilock light illuminated as well.

It should also be noted that my parking brake pedal DOES NOT LOCK in place and I think I need a new assembly from a yard cause I can't find them online.

Any idea what I could be missing? I hope I'm not too far off from a fix. Any info is greatly appreciated! Thank You.
 
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RonD

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Good work

Best bet will be to remove the parking brake assembly and have a look
It uses a ratchet with a spring to hold pedal down/locked, the release handle pulls back the ratchet to allow pedal to come back up
 

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When you replaced the RABS valve, did it come with the controller? Many years ago the RABS light came on in my 89 Ranger after a hard braking. The brakes still worked, but the RABS was non-functional. I followed the diagnostics in my Ford repair manual and came up with a bad controller. It has been a long time ago and a little foggy on the details. What I recall was it is attached to the top of the RABS valve and is fairly easy to replace. The RABS valve was still good and once the controller was replaced the light did not come back on and the RABS started working again as it did before. (Marginally effective)
 

A4LD_Nghtme

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When you replaced the RABS valve, did it come with the controller? Many years ago the RABS light came on in my 89 Ranger after a hard braking. The brakes still worked, but the RABS was non-functional. I followed the diagnostics in my Ford repair manual and came up with a bad controller. It has been a long time ago and a little foggy on the details. What I recall was it is attached to the top of the RABS valve and is fairly easy to replace. The RABS valve was still good and once the controller was replaced the light did not come back on and the RABS started working again as it did before. (Marginally effective)
Yes, it is just like the one I took off. And it is connected to the connector.
 

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