I have a 1997 Mark III E-150 Conversion Van. I have just replaced everything there is to replace in the break system. The only thing I haven't replace is the ABS system pump and the computer module. The ABS light goes through it's self test at start up and the light goes out. There are no codes, active or stored in the computer. This is what I have done so far. All new steel and rubber lines, New rear wheel cylinders, New rear Drums/shoes/and hardware, New rotors/pads/and calibers, New master cylinder, New brake booster. The vehicle does stop but the pedal is always soft and goes almost to the floor. I would say with some force I could push it to the floor if I wanted to. I am afraid that some day I will have to make a panic stop and it won't stop in time. I have tried the panic stop and you can feel the ABS kick in on the pedal and hear the pump. But by the time the truck is stopped the brake pedal is nearly on the floor.
I have bleed the system a dozen times, both pressure bleeding and gravity bleeding. I have done the bleeding from the right rear, left rear, right front, left front. I have bleed the system as found in the FORD factory manual, which by the way is different from the usual way we normally do it. I have even purchased a "New Generation Star" Service Unit and have performed the "Service Bleed Procedure". Probably have done that a dozen times. All in all, no change in the pedal, Soft & Mushy. There is braking when you first push the pedal, you can feel it. But to get any real positive stopping action you just have to keep pushing and the pedal keeps on going down. If you pump it, it does not pump up.
I have heard from other Ford E-150 owners that they have the same problem. And no one seems to have a fix for this. Is this an inherited brake thing with the E-150's, the braking system isn't big enough for the vans weight?. This Conversion van has to be close to 6500 lbs if not more.
Someone had mentioned on another forum to change the 15/16 bore rear brake cylinders to the larger 1-1/8 bore brake cylinders from an E-250. They said they would fit because the footprint was the same as the smaller cylinders. Has anyone tried this. It would make sense, it would put about 20% more braking pressure on the rear shoes. I wouldn't care about the shorten life of the shoes if I could feel that I could stop better.
Also has anyone tried going to ceramic pads and slotted/drill rotors in the front with any success? Does anyone know of an aftermarket front disc set up that will improve breaking and getter a better feel in the break pedal?
I have tried everything I know at this point and I've been doing this for 50 yrs. I've always have had the thinking your never to old to learn something new. I've never had an issue like this.
The only other thing that comes to mind is, there's air in the ABS that's just not bleeding threw.
Thanks in advance, Dave

 

Do you have rear ABS or four wheel ABS? It could be the module itself, but usually when they go bad they don't allow fluid to return and they keep the shoes engaged. I've never heard of one failing the way you describe.

But it really does sound like air in the system. Did you bench bleed the master cylinder when you replace it? Because of the way the cylinder is mounted, air gets trapped in the front of it and no amount of bleeding will remove it.

 

Hi. It is a 4 wheel ABS system. Yes I did bench bleed the master before I installed it. I also adjusted the rod in the booster as someone suggested in one of the post on this forum and another F150 forum. Adjusting the rod did make a difference. I've turned it 1-1/4 turns. I'm afraid to go anymore then that. The brake pedal is a little firmer, but for the most part still a little mushy for my liking.

 

Ok, that was going to be my next question anyway. When you replaced the booster, did you count the number of turns required to remove the nut and then duplicate that on the new booster? If not, then there is a procedure in the factory service manual that explains how to set the depth correctly.

 

Andym,

I looked in my Ford manual for that booster rod adjustment procedure, didn't find a thing. When I replaced the booster I used depth mics to measure the rod as to how far it was in the hole. I also measured the old master and the new master from the flange to where the rods sits. I did read somewhere one time the space between the tip of the rod and the master is suppose to be about .10mm (.004" to .005") , that's pretty tight. At this point I don't remember what I have it set at in moving the rod adjustment 1-1/4 turns. I'd like to hear about that adjustment procedure that's in the Ford manual to see if it is some what the same as what I ended up doing. I could be way off because I was taking my measurements of the old units. There could of been a replacement of the booster or the master before I got the van. The Van has about 120,000 on it. i don't think the booster was changed, but the master could have. I didn't look for Ford part tags when I removed them. I believe the booster did have a Ford part number "sku" on it. But again I would like to see or hear about that factory procedure you had mentioned. Thanks, Dave