So I have a 99 Ford Ranger, 2.5l 4cyl, 2wd, 2 wheel ABS, Automatic. A few months ago my brake pedal started either not going down, going down in a strangely crunchy way, going down in steps, or just going to the floor. I've done wheel cylinders, calipers, master cylinder, booster and just now a new hose on the left side. I did one of the rear cylinders and the hose today because for some reason that side doesnt bleed very well or at all, as in no fluid or very little. Ive bled the thing almost every day on all four sides including the master cylinder multiple times. I get fluid mostly of the right side pretty well, the left side not so much, or just not at all. Im not losing fluid, there are no leaks. When I went to bleed the new hose today im not getting any fluid or just tiny dribbles, while other wheels a few days ago would shoot ten feet in the air, and then not at all. Right cylinder was done a few years ago, so the only thing I havent replaced so far is the main lines on the frame rail and off the master cylinder itself, the right side hose, and this weird aluminum block that looks like it has two solenoids on it and im guessing ABS involved using logic and the way the lines are routed to and from it. What is the aluminum block and is that my final culprit? Right now I have no brakes or pedal at all when I start the vehicle and im picking up brake fluid as I see it now as a habit from the all bleeding attempts ive made.

 

2 wheel ABS only effects rear brakes, and that's only 30% of the braking

So your problem is mostly with the front and that's a separate system from the back

On the master there should be 2 lines out
The rear line is for the front brakes and the front line is for the rear brakes
Inside the Master there are two separate chambers so when you press on the pedal the piston in the master slides forward pushing fluid out of both chambers, 70% more to front brakes

The rear line on the master should go down to a Splitter, one line going out to each front wheel

The front line on the master should go down to the ABS module, then one line out to rear wheels, splitter is above the rear axle

yes, it could be the master has failed, even if new, the seals on the piston are leaking so piston is not forcing fluid out, fluid is just passing by the seals

Unless the ABS and the rear brake lines are leaking fluid they wouldn't cause the pedal to the floor issue

In order to push the pedal to the floor the fluid has to be going somewhere, so either its leaking out of a line OR no fluid is being pushed out(bad master)
It would be hard to let in enough air to not get any brake pedal push back

The left and right front are on the same line from master, just a splitter is between so they should have the same "flow"

Rear just has the one line from master and splitter is above the axle

So not sure how you could get different flow from one side or the other????

 

After borrowing a power bleeder and finding a couple drips I now have brakes again. It was dripping at the new hose and one of the master cylinder lines with the increased pressure.

 

Good work

 

And were still back to the pedal locking up and not pushing down, but at least it doesnt go to the floor anymore. Replaced both front calipers and bled the system, changed the vaccuum hose. If I let up on the pedal a bit and then push back down I can get brakes again.

 

Not sure what you mean?

But have you checked the brake pedal assembly, up at the top of the brake pedal there are 2 bushings that the brake pedal rods sits in, while rare, these bushing can wear out causing brake pedal to shift positions causing odd occurrences when pressing pedal down

 

The linkage was fine when I replaced the booster, didnt notice anything with play or sticking. It also just started to do this a couple months ago all of a sudden. The brake pedal will not go down 50 percent of the time, as in, im coming to a stop and I put my foot on the pedal, it wont move at all, so I have to let my foot off and then push again once or twice and then it will push down to engage the brakes. Once the pedal is down, on occasion it will start to go down even further in increments, as in I can feel the pedal stepping down further in small increments, during which I have to let off and push down again to reengage the brakes. Only thing left to replace at this point are the main lines, or my new master cylinder is also bad.

 

Test booster first
Start engine and then count to 10 and shut it off
Press brake pedal down as far as it will go and then let off
Repeat
You should get 3 pedal presses with "power assist" then pedal will get hard to press, no power assist, vacuum is used up

This is why the booster is so large, so it can hold a reserve of vacuum to assist in braking if engine should stall while driving
The plastic elbow on the booster's vacuum hose connection is a Check Valve, it allows air to be pulled OUT of booster by the engine when its running, which creates a vacuum(low air pressure) inside the booster, but the check valve will not let air IN when engine is off, so it holds the vacuum

Inside the cab on the booster is another valve, the "atmosphere" valve, it lets in outside air pressure, 15psi, when the brake pedal's push rod pushes it in, this is where the "power assist" comes from
Since the air pressure inside the booster is less than outside air pressure, this pressure difference "assists" you in pushing on the Master's piston
During the above test you might HEAR the air flowing into booster when brake pedal is pressed, you wouldn't hear it with engine running, unless it was leaking

 

The booster seems to test fine, it even goes down a bit when I start the vehicle. Im going to pull the check valve out tomorrow on the engine side and see if it's being wonky making everything behave erratic.

 

Well I cant get the check valve out, but when I pull the hose off it stalls the engine. I can keep it running by putting my thumb over the end but it's pointless. I ordered another new master cylinder from napa.

 

Replaced the master cylinder again and it didnt make any difference.

 

You may need to get a mobile mechanic to check out the brakes

The system really isn't that complicated so something is being overlooked and a fresh set of eyes may be able to figure out

What about the pedal itself?
There are bushings at the top for pivot point, if bushings are worn then pedal can shift, maybe lockup and or change position, so not a "brake" issue at all, a mechanical issue

 

Ive looked at the pivot area myself with a flash light upside down on the floor moving it slow back and forth and nothing seems to shift or lock up or any of that. It's just a roller with two contact points on the ends. When sitting at a stop light occasionally it will incrementally lose pressure in steps, almost like a super slow motion ABS activation, that or sometimes it just seems crunchy at the bottom and I have to let off and rework the pedal to get it to reengage.

 

What is this and why do my brakes work better without it plugged in?

 

That's the rear ABS proportioning valve, expensive to replace, and ABS didn't really work that great on Rangers

You can by-pass it and add an adjustable proportioning valve, leave that ABS unit as is and plug it back in if ABS light wasn't on

Proportioning means 70% of braking power goes to front brakes and 30% to the rear, thats for a pickup truck, cars/SUVs used 60/40

So the proportioning valve limits flow/pressure to the rear brakes, so front brakes get more

You could just by-pass the ABS unit and get 50/50 braking, you may or make not like it, you can always add a proportioning valve

 

That part number should be 12-2029. It's a cardone part number. Any of the parts stores should be able to get it. They do corrode inside and could cause your problem.

 

I think im gonna leave it as it is unplugged for now, it's a 170ish dollar part.