Ford and Spongy brakes

[5.0L96Exp]

I still think we are on different pages here. There is no proportioning valve per say. The "proportioning" is built directly into the HCU and MC. That is, the MC determines Front to Rear brake pressure (via different pri/sec spring rates), the HCU determines (while ABS is activated) the pressure applied to the FL, FR, and rear brakes. ie the HCU can raise/lower pressure to the FL, FR and rear brakes as needed to prevent skidding. There is no way "proportioning" could be after the HCU since the HCU has 3 outputs, 1 for the FL, 1 for the FR, and on for the Rear brakes. It simply doesn’t make sense. Also, there are only 2 lines into the HCU, one from the MC primary and one from the MC secondary.

However, the original question remains. Which valves open/close when the VALVE button is pressed? And where does the air in the HCU end up after the 60 seconds. It seems to me, from the HCU fluid routing diagram that when the pump is running, the DUMP and ISO valves are opened, the accumulators will fill with brake fluid under pressure forcing any air around in a loop. Unless of course the HCU is designed with some sort of loop de loop routing that causes the air to get stuck in the primary leg. Once all the air is trapped in the primary leg, (the DUMP valves are now closed restricting fluid from entering back into the accumulators), the brakes are bled normally starting with the RR, RL, FR, FL.

If anyone has the name and number of a Ford dealer that is willing to let you talk to a tech and ask all sorts of questions it would be greatly appreciated. I have yet to find a dealer that is willing to answer any technical question, or any question that would in any way make them liable. ie The moment you so much as mention brakes, abs, airbag, cup holder, floor mats they tend to freak out and tell you to they will have to look at it and replace the parts as needed.

 

[BrooklynBay]

My local Ford dealer is the type that if you ask any question, they tell you to ask one of the mechanics. If you go to a mechanic, they say that no customers are allowed in the service area due to insurance regulations. If you say that you have a technical question, they tell you to go into the office. The office tells you that no customers are allowed there, because it's reserved only for mechanics to look things up in their manuals. If you ask a mechanic to look something up for you in their manual, they tell you that they don't have the book anymore on your vehicle, but you should schedule an appointment to have it serviced. If you ask them how they would service it without a manual, they tell you that all of their information comes up on a display on their scanner once they hook the vehicle up to it. I think they have a minimum of $75 just to look at it. After customers get such a run around from them, I can't understand why anybody would give them business.

 

[CDW6212R]

Well, color me surprised at Ford. I look at pictures that I took of my 99 V6 Explorer, and the brake lines do go straight from the master cylinder to the ABS unit. The proportioning valve function is evidently integrated into the MC now.

The combination valves of past have always been very very reliable, hardly ever fail parts. That may be why it would be included in the MC now. But anyway, that leaves the master cylinder as a more important part now.

I have a good Ford tech that I sometimes can catch to ask questions of. He would likely try to help with the Ford ABS tool. Still may I suggest that you send Glacier a PM, and ask for his help with the ABS functions. He has some knowledge of those tools, etc.

 

[1-Dragon]

I found this on the web http://www.sccoa.com/forums/archive/index.php/t-29670.html

Duffy Floyd says :
08-22-2003, 10:40 PM
Ad if you go to the Ford Shop Manual it tells you to bleed the Brake Master Cylinder and ABS Hydraulic Control bracket you have to use the Ford T90P-50-ALA ABS Test Adapter or air will be trapped in the ABS Hydraulic Control Bracket which will lead to a spongy pedal.

On EBay you see a Thexton tool which does the same thing as the above mentioned special tool sold often for less than 29 bucks. Search on Teves ABS and you should be able to find one.

I didn't find one on ebay though but this might help U



UPDATE:

I found one on ebay 5 items available at $38.95

http://cgi.ebay.com/ebaymotors/THEX...ryZ43989QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[BrooklynBay]

Thanks for posting that link. Do you have another link that explains how to use it, where to connect it, and a list of applications that it could be used on?

 

[Doubt Incarnate]

drive a 96 bravada, then your ex, explorer brakes rock!

 

[exploded99]

There are rebuild kits for the MC, but you may have to order one, as most people do not rebuild parts anymore, so stores don't stock them. Call one of the better parts stores. It should only take a couple of days to get one.

 

[1-Dragon]

@BrooklynBay: sorry i saw the price and knew i couldn't affort it this month so i didn't look into it any further
Thought it might be more usefull for u guys
Seems it comes with a manual which should explane more
A search for the company website might help out i guess ?

 

[NHale623]

Does anyone know if the referenced tool, Thexton Teves IV 133, will work on a '95 Explorer equipped with 4WABS?

Thanks,

Steve

 

[uhmgawa]

Spongy brakes - UPDATE.. HCU fluid routing diagram

Anyone ever find where/if the hyd diagram discussed here may have
been captured? I likely need to bleed the antilock manifold on my '93
and would like some insight into the hyd circuit before I mess with it.

I do have the electrical schematic for the vehicle. From this and given the
usage instruction of the T90P-50-ALA bleeder box it would seem a low
cost solution homebrew solution is indeed doable.

5.0L96Exp: UPDATE: I am on crack.. I have come across a hydraulic fluid routing diagram for the HCU and I can now explain in detail exactly what happens when the ABS is activated (well a heck of a lot better than I could before). A picture is worth a 1000 words so I won’t even attempt to explain in detail what happens. Email me for the pic since I can’t seem to post it.

It is also worth mentioning that the DUMP valves seals can fail and allow brake fluid to enter the accumulator. This IS VERY OFTEN confused with a failing MC since they give the same spongy pedal feeling.

 

[01tracsport]

i had a very similiar problem to this and it turned out i had the wrong pads and rotors on. go to the dealership with your vin and get the correct parts and compare with the parts you have. if they are the same return them. if there are not you know its the new pads you put on.

 

[CDW6212R]

2001 and newer Sport Trac's and Sport's have 12" rotors, different calipers and pads. The calipers and pads are very very similar, but not really interchangeable. I had bought a set of 2003 calipers, and compared them to my 99 parts.

The 95-01 calipers, and pads, are better parts. The pistons are steel, and the pads are larger(they will last longer). The later calipers are designed with ceramic pistons(anticorrosion), and the pads are smaller because of the larger rotors.

I have those 2001 rotors/spindles on my 99 Explorer, I will use them up before changing to my better custom 12.75" brakes.

For a spongy pedal, first do all of the proper fluid bleeding and parts replacement. If afterwords the feel is still not right, assume that some air is in the ABS unit, and have that bled with the special tool. Go straight to that, it's very good maintenance that many many vehicles probably need. Regards,

 

[pservecc]

My current dilemma...

I changed front rotors/pads twice, rears once, on my 98 XLT. Never had a problem with the brake pedal feel.

A few weeks ago, one of the hard lines let go and I had it fixed at a dealer. Brake pedal is now softer than before, even though they said it was bled twice (with the proper ABS tool). The fluid and the lines were the only things changed. They insist it's fine, but I know it's not. Last time I was there, the tech told me that the HCU valves are normally open and the tool isn't even necessary to bleed it. I don't believe anything they say anymore, though.

 

[CDW6212R]

It sounds very much like where you went did not bleed the ABS unit with the special tool. It is likely that who worked on the truck didn't know what he/she was supposed to be doing.

I have spoken with a very competent mechanic about many many things, including the ABS. Either try again through a higher level person there in the service department, or go elsewhere. Good luck,

 

[DCExplorer]

To the best of my knowledge, no one has yet to chime in anywhere in this forum to say that bleeding the HCU has fixed their spongy brake issue. If it is here somewhere I would like to see it. Yes, I've searched.

I have new calipers, rotors, and shoes, all the way around. I've bled the brakes repeatedly, and my pedal still doesn't seem right. I'm currently debating my next step. I'll either take it in and have the HCU bled, or I'll just put a new master cylinder on it and hope for the best.

edit: Oh yeah, and I replaced the brake fluid too.

 

[CDW6212R]

I agree, feedback on repairs is rare. I trust my mechanic source, I still have my 95 Crown Vic which needs that ABS bleeding, but it's not high on my to-do list.

It is still common for people to jump to old theory conclusions about repairs. Vehicles have changed a good bit since the mid 90's, and it can save time to do basic things first, then jump straight to new possibilities, not old ones.

Brake systems, all of them, rely massively on brake fluid and brake pad quality, those should always be a first priority with any brake work. People skip or skimp on those most of the time. Do those first, then assume that somehow air has gotten into the ABS unit if the sponginess persists.

It is not easy to change a master cylinder, and not have any air get in the system upstream of the ABS unit. Any air up there has the possibility of getting into the ABS, whether air was in it to begin with. You stand a good chance of having to bleed the ABS unit anyway, even if the master cylinder is at fault.

Unless some major symptom exists, I'd assume that the master cylinder is not the problem. Those master cylinder issues often are not very mild or soft pedal problems. Often those involve a serious lack of braking ability.

My 95 Crown Vic had all new or known good parts, and the pedal was a little soft. Basically it just takes a little more pressure to do the work. It just didn't feel as good as my other 95 Crown Vic. Good luck,

 

[presite]

So.. anyone have luck getting a new Explorer sport track brakes to act solidly.. as opposed to a 'marshmellow' when
new? Does this improve or where should I suggest the dealer 'look'?

 

[CDW6212R]

Either air is still in the system, or the fluid is very dirty, or air is in the ABS pump. Bleed new fluid through it again, without letting more air get in. Do that with two people and bleed it until the fluid is completely clear. Good luck,

 

[uhmgawa]

Antilock design from Hell, was: Ford and Spongy brakes

To the best of my knowledge, no one has yet to chime in anywhere in this forum to say that bleeding the HCU has fixed their spongy brake issue. If it is here somewhere I would like to see it. Yes, I've searched.

I should have followed up to this group after my '93 Xplorer brake-ectomy.
The hard line over the driver's rear wheel let go on the highway (naturally)
and when I investigated the failure I found the rest of the system was
soon to check out as well. I replaced *every* hard/resilient line in there
as well as all hydraulic components sans antilock unit and master
cylinder. The antilock valve is a (Continental) Teves Mark IVg which is an
internal hydraulic accumulators design rather than one with a return line
back to the main reservoir.

So the problem suspected in my case was the location of the
accumulators behind internal check valves wouldn't allow purging of
captive air unless the pump and dump valves were operated together.
I'm now a bit foggy on the sequence I used but I was able to get the
procedure from Autozone's online repair manual which described
such using a Ford $500 $pecial $ervice tool. I just reversed
engineered what the box was exercising when the procedure was
followed using the antilock hydraulic schematic and bled the unit.

I needed some way to actuate the dump/iso valves as well as
pump so I pulled the harmonica connector off the controller
module. After finding some weather stripping nails to mate
with the small contacts and carefully bent pins from paper clips for
larger contacts I made a crude cable which did the job. You'd need
the electrical schematics for the vehicle as well (or at least antilock
controller) in order to know where to find the valve coils and pump
relay lines in the connector.

If anyone is really interested in the above for those problematic model
years (I believe 1994 and under) I can dig up the directions and
archive them if given a pointer to a suitable location.

 

[Minivek]

I'd be interested in all the info you have on the subject, I wouldn't mind fabbing my HCU bleeding unit, it would avoid trips at the dealership when the hcu goes dry for some reason.