Alright, I guess here goes nothing.
My name is Karim, I'm from Germany and the owner of a 2000 Excursion 4x4 V10.

I bought the truck on eBay last year, sight unseen. I knew the truck would have some problems because it was sitting for about 2 years after the inspection (TÜV) expired.
Long story short, I'm having some weird brake problems.
I overhauled all brake calipers with new (plastic) pistons from Centric and new seals.
The X sat for about 2 months without any calipers attached so pretty much all of the brake fluid drained out.
After trying to bleed the brakes for the first time with the "new" calipers, I experienced this weird problem:
Building up pressure while the engine was off wasn't a problem, but after waiting for about 2 minutes the pressure was almost gone and I had to pump 3-4 times to build it up again. With the engine running there was no pressure build up at all, the brake pedal went right to the floor no matter how many times I pumped.
Then I discoveres this: While pressing the pedal, there was a "whoosh" sound coming from the engine bay, probably from the booster.
But when I released the pedal there was a wooshing sound from the ABS module and big air bubbles were coming into the reservoir from the master cylinder's rear port (the one closer to the booster).
I then thought the master cylinder developed some corrosion on the inside because it was empty for alonger period of time. I bought a new one from Centric but the problem appeared again.

That leaves me with the ABS module. It seems like it doesn't let fluid out when depressing the pedal, but when releasing it lets air in which then comes out in the reservoir.
I took the ABS module assembly apart as far as possible, couldn't find anything and put it back together with new o-rings.


I hope someone can help me out on this one because at this point I don't really know what to do other than to buy a new ABS assembly which is about $500.

Thanks
Karim

 

I'm not 100% positive but I think that you will need to use AutoEnginuity, ForScan or some other type of plug-in computer tool to force the ABS module to active(or de-activate) to allow for a good brake bleeding once the module has been drained of fluid.
I have never needed to do it, hopefully someone here with first hand knowledge will jump in to confirm.

 

Yes, as WE3ZS stated, you'll need to cycle to ABS module to push the fluid through it. I would properly bleed that and see if it cures your problem. I'll try and get on my other computer later that has the factory manual and get the procedure that the factory describes for you. You might check Google/YouTube in the mean time.

 

The ABS module will eventually bleed the air out. But you might be on the extreme side of that scenario.

I let my brake reservoir run dry accidentally while bleeding the brakes and it sucked a bunch of air in.

The brake pedal was spongy for a month or so before it was noticeably better no matter how many times I bled the brake lines.

 

Thanks for the help so far.
I totally forgot about having to cycle the ABS module, I read about that but didn't think of it anymore.
Unfortunately I didn't find anything specific to the Excursion/Super Duty's on how to cycle the unit, but I saw a video of a Chevy Silverado doing it and it looked quite easy.
Question is, am I able to do that by myself without having to buy a $1000 scan tool (rather like a $100 scan tool or just a software for the computer with OBD2 adapter)?
Really looking forward to your answer @Romanova
And I disassambled the ABS module... duh

Karim

 

Maybe this will help you

Everything below this is blatantly copy/pasted

You can bleed the abs without the expensesive solenoid cycling machine. #It's pretty easy. #Focus on the calipers. #Remove them from the rotors and pump your brakes until the pistons come out. #I put some spacers in the caliper to prevent the piston from coming completely out. #Then remove the bleeder valve and the brake line. #Don't drain the caliper. #I stuck cotton ***** in the brake line to reduce drainage. #MAKE SURE YOUR RESEVOIR IS FULL BEFORE DOING THIS! #Hold the caliper flat, so no fluid spills and proceed to pour more fluid into either the brake line hole or the bleeder hole, all the way to the top. #Might want to shake it a little to be sure as much fluid gets in there as possible. #Then reinstall the line and valve and take a c clamp and press the pistons down all the way. #I did this three times each side and fixed air in the abs system. #It is basically a reverse bleeding method and works great. I am sure I am not the only person who has done this, but I couldn't find it anywhere. A family friend and mechanic for us for the past 25 years suggested it to me. Thanks Mike at the Z Center in Houston!