Help - Ford E-350 Brake problem

Not long ago, Dan <
As a GUESS, you are abusing the brakes by overheating them to the
point that the fluid is boiling, and when that happens you get a low
pedal and brakes only on part of the system. (Hey, this is a GUESS,
ya know!) If you had a leak your Ford people should have found it -
and they SHOULD have warned you about heavy use of the brakes.

Offhand I cannot think of any other diagnosis from this side of the
keyboard.

Try going a lot easier on the brakes, shifting down to decel, and see
if the problem doesn't go away.

Will KD3XR the Curmudgeon of Sill Hill
Before flaming, pause. I post to help rv'ers
and annoy morons. Whichever shoe fits, wear it.

Dan,

Your question is getting a little dated but I just ran across it
today. Have been there and done that with my 89 E350 MH. This issue
was covered about 2 weeks ago and I'm surprised no one remembered the
discussion.

At the root of your problem is fact that your rig came with aluminum
pistons in the front calipers. They are GREAT for transfering heat
from pads to brake fluid and the piston is in direct contact with
both. Ford has had a TSB for a number of years describing this
problem and the fix. You need to rebuild the calipers and replace the
aluminum pistons with the phenolic replacements.

Another potential contributing factor is rubber dust boots are in
contact with back side of pads during first half of the pad's life.
If the pads get too hot that can and will melt the boots. Residue can
get stuck to piston which can cause drag on the piston and hinder
retraction of the piston.

Your discribed symtom sounds like one caliper is draging (cause of
pull) and then leads to overheating of brake, over heating of piston
and lastly, boiling of fluid.

The repair can be a DIY project but be warned, correctly installing
dust boot is VERY difficult without a second pair of hands or tools
especially made for this.

Hope I've been of some help.

Mickey

...

Several good suggestions here including the caliper piston. I know exactly what you ae talking about as I have a E 350 MH that I pull a 24' trailoer behind with a race car. I have learned to be careful with the brakes. They will over heat quickly. I did switch to DOT 4 fluid that has a higher boiling point. Also I have had to replace the rotors a couple of times because they crack. If you ever replace a rotor, buy the best ones you can find, not the made in China Cheapos. Good luck with this problem
Jim N.

The master cylinder or a line from it may be overheating, especially if
it's too close to the exhaust manifold. Do you have rear antilock
brakes on that van? If so, that system may not be working well or might
be contribuiting to the problem.

Tom Boles
(Who had a '90 E250 until recently and had a spot of trouble with the
brakes due to both overheating (from the exhaust manifold) and from the
RABS system...)

of the

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Before you buy.

That would be the first that I would look as well. The fact that the system
pumps back up with the pedal suggests that the internal seals on the master
cylinder are leaking and not providing the needed fluid pressure on the
first try. They can fail with leaking to the outside and causing fluid loss.

Another thing to check, since it seems heat related, is that the brake drums
and rotors might be worn outta specs. With less material on them, they would
have a tendancy to heat up more than they should and possibly cause the
brake fluid to boil. Did the shop do a complete brake fluid change?

maybe the brake fluid has filled with moisture from the years of sitting and
when its heated during stop and go the pedal fades as the water vapor boils.
I suspect i have the same problem with mine and will be bleeding the fluid
out and replacing it. good luck make sure the emergency brake is
operating :)

Dan,
I think that this "pulling" is a clue. What might be happening is that
a front caliper is sticking. If it is pulling to the right then the brake
caliper is hanging up and pulling in that direction. Same for the left.

The "shortly" was the time needed to heat and "Boil" the fluid and cause
brake fade.

Fluid and caliper cooled off.
Look for a caliper not retracting caused by dirt or ?? holding against
the rotor. Just a guess.
Vince Wirth
http://home.earthlink.net/~vincewirth