This is a 2009 E450 Diesel with a ambulance type body. Has 7000 miles. The brake pedal is very soft and seems to stop the vehicle. With continued pressure on the brake pedal it will go almost to the floor.
Every vehicle I have had the pedal is hard and does not go to the floor. This defies all I know about hydraulics and brakes.
It was taken to a Ford dealership who checked it out and said all is OK - pressures are good and no leaks.

Any ideas? I just can not accept that this is the way it is supposed to be.

Thanks for your thoughts

Russ

 

in my experience soft or spongy pedal was from air in the brake fluid,normally you get air bubbles from faulty master cylinder or excessive bleeding procedure,I would bleed brakes & if you have drum brakes on rear axle,adjust slack,that can give low pedal.

 

Got it solved - yippee! The power brake booster on this truck is hydraulic. It gets its fluid and pressure from the power steering pump. After adding almost a full pint bottle of power steering fluid - yes it was that low - turning the steering wheel back and forth a lot of times, adding another cup of fluid and driving the vehicle about 10 miles the brakes are back to normal.

So much for having the Ford Dealership check the spongy brakes.

R

 

My 2002 E450 cutaway chassis under a class C motorhome, quickly lost most of its normal brake pressure in hot, stop and go traffic on the 210 frwy near Pasadena. Heat was 104F degrees at the front wheel TPMS.
I had just made an abrupt start and stop after a bus in front of me did the same thing. The pedal reacted oddly, then started fading till it went almost to the floor, (but it still stopped, that was odd). I pulled off the freeway with white knuckles, convinced my brake line had lost its fluid from a leak. I just had it serviced 500 or so miles ago, with new calipers, rotors, pads, etc.
Calling all around, no brake shop could take in our size rig on a Wednesday afternoon or even mobile brake service was going to happen in time to make our campground reservation. But this forum and thread from Ranger Russ here saved our vacation!
On the side of the road, searching for it, tricked by AC condensation drips, then crawling under inspecting every inch for an hour, no brake line or caliper leak, what is going on?
So pulled my moto off the front carrier blocking the hood opening, huh? no low fluid issue with brake fluid either. Thoroughly confused now I asked my wife to start reading forums, where she found this post.
Then hour + of confusion with several calls with Ford and Auto parts stores, over Transmission fluid versus Power Steering Fluid called Mercon ATF and why "they" were conflating the two, when I'm just looking for Power Steering fluid called Mercon ATF!
Advantage Ford Parts clerk Robert, explained factory OEM PS fluid is now Mercon V. Now after 5 PM they were closing too soon for me to get there. I gave my credit card number purchased by phone and Robert left it for me on the Sales desk.... I got it ! riding back roads on my moto, around L.A. rush hour traffic.
I added a pint of Mercon V to the Power Steering reservoir, of course I over filled it since it kept sucking up more and reading how much Russ' needed. So when starting up and pressing the brakes it flexed outward on the thin little square plastic reservoir, which then spilled out the excess through the cap. Wiped that up over and over, pulling more out with a straw, till it stopped flexing under engine running brake presses. And yes in 10 minutes it was starting to feel normal again, after several right to left turns and braking tests around the parking lot and streets. We were back on the road to our State Park destination and we made it there by midnight.

You can judge, but realize I am a diy mechanic of 50 years, servicing most needs of my bicycles, my motorcycles, my cars, fixed every home appliance, added plumbing, electrical, remodeling, to above code levels (thanks dad for the training). I thought I was doing a good job of keeping up service, fluids and rad flushes and oil changes too.
The important part in your maintenance is to understand that even though you are checking the Transmission or PS fluid regularly, realize that the dip stick process for both is somewhat tricky. Somewhat unreliable. "Warm" (level is lower on the stick) versus the cold measurement. it should have fluid to the top of the PS dipstick in the "COLD" state. And how even if the engine is warm, your PS ATF fluid could still be cold-ish. And then there is a >50F factor to be aware of on ATF or PS fluid checks.
Do not be fooled as I was, by this PS reservoir's short 2.5" dip stick controlling so much of your rig's mechanicals.
If you have the Transmission fluid service you have to carefully read that section and how to drive it 20 miles, etc. to get good readings.
You can't rely on Dealers or Quick Oil Changers to do this to the quality level required, nor to understand and comply with your Econoline 450 system nuances.
I will be checking this much more closely in the future realizing how much of my driving is relying on this small quirky reservoir.

Thank you Ranger Russ for this important post and your detailed reports. Hope this helps others. I will be looking closely at the next Ford chassis I purchase, regarding this system.