Ford and Spongy brakes

[Thunderstar]

Bleeding Teves IV HCU

I would like to build an adapter to bleed the HCU like you were doing a couple of years ago. The info I have indicates that the pump is turned on for 60 sec. During this time the outlet valves are pulsed open sequencially at a 10 Hz. rate for 20 seconds. This should remove the air trapped in the HCU.
Then the wheels can be bled as normal. Do you have any more info you are willing to share? Did you get your adapter to work? Did it make the brakes solid?
Some are saying that bleeding the HCU does not help with spongy brakes but I am wondering if they are not being done correctly. I contacted a shop to bleed my HCU but they will not tell me if they have the T90P-50-ALA Ford tool. They just say they can do the job. I have to question if it is being done right.

 

[BrooklynBay]

Welcome to this forum! What year is your vehicle? It's not listed in your profile.

 

[Thunderstar]

teves IV spongy brakes

My son has a 97 Sport Trac. I have a 94 Aerostar, and 95 Thunderbird.
Right now it is the Thunderbird that has the brake problem.
I have found threads from people wanting to build a bleeding adapter but little info on what they have tried or accomplished.
I dont think the MarkII Teves system requires this adapter.
All that is needed is: 4 switches, 2 LEDs, 2 or 3 timers, a ring counter, and a hammer driver for each valve to be switched. The connector should be available from a wrecker. This is not tinkering with the controller. This just turns the pump on and then pulses the outlet valves one by one to purge the air out of the valve body. I find it hard to believe that some one has not done this by now.

 

[BrooklynBay]

http://cgi.ebay.com/ebaymotors/ROTU...Z400027953942QQptZMotorsQ5fAutomotiveQ5fTools

 

[96eb96]

My son has a 97 Sport Trac. I have a 94 Aerostar, and 95 Thunderbird.
Right now it is the Thunderbird that has the brake problem.
I have found threads from people wanting to build a bleeding adapter but little info on what they have tried or accomplished.
I dont think the MarkII Teves system requires this adapter.
All that is needed is: 4 switches, 2 LEDs, 2 or 3 timers, a ring counter, and a hammer driver for each valve to be switched. The connector should be available from a wrecker. This is not tinkering with the controller. This just turns the pump on and then pulses the outlet valves one by one to purge the air out of the valve body. I find it hard to believe that some one has not done this by now.

I wonder if the valves are PWM driven and could be damaged if you apply too much of duty cycle to them. There is a scan tool where in the near future brake bleeding will be added. www.obd-2.com. You can inquire with him for more details. I was told in the next few months. It is usually done thru the OBD port, and there is software in the unit to accomplish this.

For the 95 tbird (I have one too) it has its own ABS connector so it would definately need a proprietary tool or something like you want to create to bleed it.

 

[Thunderstar]

I do not see why PWM would have been used. The idea I think is to stop the speed difference (slip) as quickly as possible.
Pulse the dump valve on then off and repeat until the wheel speed comes back up to match that of the others. Any lowering of the dump time would only slow the process.
Most relays and solenoids that have a substantial mass to move, take about 15 to 25 milliseconds to physically move. I think a dump valve that can switch 2000 psi brake fluid will also fall into this category.
However, to be safe it would be easy to make the on time adjustable. Just start out with 25 millisecond on and 75 ms off. If this does not open the valves increase it until it does.
Also by sequentially pulsing all 4 output valves, one at a time (for bleeding) the off time becomes about 8 times the on time for any given valve.

 

[cmshaver29829]

mushy brakes

:rangergreen:OK I am having a similar problem with this. I was waiting for a train to pass and the brakes went all the way to the floor. I have bled the heck out of the front calipers. There is no fluid loss. The rubber grommet on the vac hose to the booster was a little worn and I silliconed it really well. It probably didn't need it because there was pressure on the line when I pulled the fitting out of it. Is there supposed to be? Is this fitting a one way valve? How do you know if a booster is bad? I hear a hissing noise coming from it when I depress the brake pedal. Also someone had mentioned an ABS valve on another forum that is supposedly located underneath the driver's side front. Does anyone know anything about that? A picture would be great but I'm having no luck finding one.:rangergreen:

 

[01EB5.0]

For what its worth...the brakes in my explorer and F350 seem softer then any 4 door sedan i drove. The brakes were soft in my mom's old e150 conversion van too. I thought it was just a ford truck thing...

 

[cmshaver29829]

at a loss...

Maybe so, but for the brakes to be working well and to all of a sudden go to the floor indicates a serious problem. Today the front brakes did not work at all and I had to stop using the parking brake. Obviously the rear brakes work. I just wish that I knew more about this brake booster. I have never had one to go out and I really don't know how it comes out.:thumbdwn:

 

[Thunderstar]

You said you bled the front. What about the rear brakes? Did you bleed them? When you pulled the line off the booster was it vacuum you heard and not pressure?
Without the booster your brakes should still be able to stop the car/truck. You would have to put a lot more force on the pedal though. Really stand on them. Have a look at this link for some more info.
http://auto.howstuffworks.com/auto-parts/brakes/brake-types/power-brake.htm
I think I would be looking at the master cylinder for the problems you describe.

 

[kylemarks2003]

spongy brakes

i was driving the other day when i stoped at a stop sign and my brakes went spongy... i changed the master cylindar and bleed all 4 brakes they are still spongy but only when the truck is running. they still work but i realy dont want to keep driving like this can anyone help?

 

[CDW6212R]

Welcome, and first consider the condition of the brakes. They need to have clean fresh fluid in them, when was the last time they were bled?

If the ABS light comes on then check the ABS sensors, they sometimes produce faulty signals, usually from being dirty. Check over the brake system and see if everything is serviced before assuming a bigger problem. Regards,

 

[Thunderstar]

spongy brakes

spongy usually means air in the system. Before you changed the master cylinder was the fluid level low? low brake fluid can let the system suck in air.
When you installed the new/rebuilt master cylinder did you bleed the air out of it before you bled the brakes? some m/c have a bleed screw, others require a line to be loosened.

 

[DillonMarino]

We have a 98 Ex XLT and it has had this squishy brake problem since we got it. Everytime we have to stop it is like rolling the dice. I will get the ABS bled and report back. Bottom line I was too scared to let her keep driving it so we got her a Jeep, with working brakes. I am just trying to fix it b/c we will not sell it with no brakes but my recommendation is sell the explorers and buy a cherokee.

 

[Mbrooks420]

HAHAHA. Yeah, that's the ticket. And when something on the Cherokee needs adjusted/fixed/replaced, are you going to run out and buy something else? Explorers generally have good braking, especially compared to some other SUV's out there.

 

[CDW6212R]

All of the ABS systems from the early 90's and on have to be electronically bled to get air out. I hope you have the fortune of finding a Cherokee with air in the ABS module.

Let's see, Ford is still an American owned and run company, Chrysler is now Obama Motors and owned by the government and the union which killed Chrysler. Why not buy a socialist/fascist made vehicle, that should turn out well don't you think?

 

[Kellman]

Soft/spongy only when running?

I had a similar issue in that I suddenly had soft/weak/spongy brakes but no fluid loss. Seemed fine when the engine was off; very hard and easy to pump up, but the pedal sank to the floor as soon as the engine was started.

Of course, everyone says, "Air in the lines!" or "Bad master cylinder! It's leaking past the seals!", including my father, a retired mechanic. Flushed fresh fluid through (needed it badly anyway) but no air comes out and pedal still soft. So, replaced the M/C with no benefit except for the first 10 seconds after bleeding. Tons more research, everyone says, "Well, air in the ABS system then! Get the special scan tool! Can't find it? SOL then!"

Nonsense. The ABS system sets the braking pressure, regardless of the pedal pressure, and is the problem here but not because of air in the lines. A valve or expansion gate is stuck open in these units allowing for very minimal pressure to the wheels, allowing your pedal to drop to the floor quite easily.

Go to a gravel/dirt/sandy/snowy/icy road or vacant lot, get up a bit of speed, and then hit the brakes as hard as you can, attempting to force the ABS system to engage. After doing this a few times, check your brake action again. You'll notice that it is suddenly firmer, and you stop like you expect to again. You'll probably even notice it after the first time the ABS kicks in (that clicking sound, etc.).

I've seen this exact issue with other makes and models, so it seems to just be a problem with ABS systems that don't ever get activated.

So, if you know you don't have a leak or obvious problem, try this first before spending $$$ on parts. I've seen posts with people replacing almost their entire brake system with no positive result when the stuck ABS system is to blame and no replacement is necessary.

If you *know* you still have air in the lines, the above can also be used to help purge the air out of the ABS unit so it can be bled out normally as well.

Kellman