jauguston
Bellingham, WA
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I agree with Dave on the wild advice. You got your brakes too hot and the brake fluid boiled.You surely don't have to replace all the stuff suggested to make it safe. Change the fluid and use less brake on the hills from now on. Use the engine compression to hold you back by selecting a lower gear.
Jim
2005 Coachman Sportscoach Elite 402 40'
350hp Cat C-7 w/MP-8
7500w Onan quiet diesel generator
6-Kyocera 130w solar panels SB3024i MPPT controller
Pressure Pro TPMS
1987 Suzuki Samurai tintop Toad w/VW 1.6 turbo diesel power
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Swampyz
Sac. Ca. USA
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Thank you to all that responded and for all of your advice.
Here is a little more info. I have owned this truck for eight years. When purchased it had 91000 miles and now has 104000 miles on the odometer. When I bought the truck I received the maintenance book with all receipts. The front calipers, rotors and pads had been replaced the year before I bought it. When I replaced the master cylinder I bench bled it (I like your DYI kit Ben) and flushed the entire system. I have inspected the entire system after the latest and it has no leaks.
At this time I am leaning towards,
Leaving the Master Cylinder alone as it is just four years old
Replacing the current fluid with DOT 4 Valvoline Synthetic fluid (Bens advice)
Replacing the current brake controller with a Prodigy
I am on the fence concerning the rubber brake lines and the rear cylinders. The comments about the age of the rubber concern me. Should they?
Again, many thanks to all that responded. If I find anything out of the ordinary this weekend I will repost.
Swampy
2003 Aljo 261LT
1993 F250
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Dave H M
IL
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Aaaaa Haaaa, you would make a good poker player. Seems you kept a lot of down cards. 
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Turtle n Peeps
California
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Joined: 06/23/2008
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Swampyz wrote:Thank you to all that responded and for all of your advice.
Here is a little more info. I have owned this truck for eight years. When purchased it had 91000 miles and now has 104000 miles on the odometer. When I bought the truck I received the maintenance book with all receipts. The front calipers, rotors and pads had been replaced the year before I bought it. When I replaced the master cylinder I bench bled it (I like your DYI kit Ben) and flushed the entire system. I have inspected the entire system after the latest and it has no leaks.
At this time I am leaning towards,
Leaving the Master Cylinder alone as it is just four years old
Replacing the current fluid with DOT 4 Valvoline Synthetic fluid (Bens advice)
Replacing the current brake controller with a Prodigy
I am on the fence concerning the rubber brake lines and the rear cylinders. The comments about the age of the rubber concern me. Should they?
Again, many thanks to all that responded. If I find anything out of the ordinary this weekend I will repost.
Swampy
Since the brake system is a closed hydraulic system there are only two ways a brake system can go to the floor.
#1. You have an external leak. You say you have no leaking fluid so that leaves this one out.
#2. The master cylinder is by-passing internally. This means that the fluid is going past the seals and the pressure is not being transfered to the slave cylinder.
This is the only two options that you have when, as you say, "the peddle went to the floor."
I have had both problems happen to me. One time I broke an AirEqip line going to the front system. Another time I had the MC by-pass on me and the peddle went to the floor because it did not have enough throw to pick up the rear system.
If the brakes got soft and or were hot and ineffective that is a whole different kettle of fish and many more things can cause that.
~ Too many freaks & not enough circuses ~
"Life is not tried ~ it is merely survived ~ if you're standing
outside the fire"
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EMD_DRIVER
Gerrardstown, WV
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Wild advice? Hmmmm.. Ok..
"A common complaint on Ford light duty trucks with the rear anti-lock brake system is that the brake pedal will fade while under steady pressure. In a conventional brake system this would point to an external fluid leak or an internal leak (bypass) in the master cylinder. Generally, one and usually two master cylinders have been replaced already, leaving one very frustrated technician. In this system there is one other possibility - the rear anti-lock brake valve. This valve is the electro-hydraulic proportioning valve located on the left-hand frame rail between the master cylinder and the rear brakes. This valve controls the brake fluid during an anti-lock stop by restricting or bleeding off rear wheel cylinder pressure.
To better understand what's happening, let's take a quick look at system operation. The RABS module continuously monitors rear wheel speed by means of a sensor installed in the rear differential. When the sensor signal to the module shows a rapid decrease in speed - indicating rear wheel lockup will occur - it energizes the isolation solenoid in the RABS valve. By doing this, the normally open valve is now closed, blocking off the line to prevent further brake fluid from entering the rear wheel cylinders. If there is still too great a decrease in rear wheel speed, the module will then energize the dump solenoid in the RABS valve. This solenoid is normally closed and, when energized, will open a port to the accumulator and bleed off some of the pressure to prevent lockup. This fluid is then stored until normal brake functions are resumed and the fluid is returned to the master cylinder.
If rear wheel speed is now OK, the module de-energizes these solenoids to resume normal braking. If speed decreases too rapidly again, it resumes anti-lock control. The module will alternate between the two solenoids and normal braking until there is no further chance of locking up or vehicle speed is now under 5 mph.
The focus is on this dump portion of the RABS valve. Occasionally the seat between the solenoid and the accumulator will leak, causing the pedal to fade during normal pedal applications. This sinking pedal has no other abnormal braking characteristics and is usually not noticed (depending on severity) unless it sits for an extended amount of time with constant pressure applied. It may be due to physical damage or a buildup of contaminants in the hydraulic system, but the results are the same.
Some customers report that the brakes were just fine until a hydraulic component was replaced or repaired and the brakes were bled. Then the pedal started fading. Quite possibly this is due to a new problem that is created by "moving" some of the contaminated fluid into the valve. To diagnose this system, like all brake systems, first verify that there are no external fluid leaks. If visual inspection is OK, disconnect the brake lines at the master cylinder and plug the outlets in the cylinder. When the master cylinder is plugged, if a fade is still experienced, the master is at fault.
If, however, there is no fade, determine if it is coming from the front or rear brakes by blocking one port at a time at the master cylinder. If there is no longer a fading pedal when blocking the port to the rear line, go one step further and build a short brake line to splice between the inlet and outlet lines at the RABS valve to temporarily bypass the valve.
After bleeding the rear brakes and verifying there is a solid pedal, it's a good bet that the problem is in the valve itself. The next step is to replace and bleed the valve (if equipped with a bleeder) and the rear wheel cylinders. Verify the repair and road test."
2003 Sunline F-344SR fifth wheel
1999 Ford F350.. 7.3 Dually
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LITEPHIL
AZ
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Joined: 07/02/2003
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Its important to determine weather the brakes faded or the master bypassed. If the brakes faded the pedal would still be hard but you need much more effort. You can usually smell them if they faded. If the master went out you can usually sit at a stop and just sort of push the pedal a little and ease up and then back down and you can most of the time work it down and verify an issue BUt the newer dual masters will trigger the light if the presure between the front and rear chamber are different. I would guess you over heated them. Use your gears and slow down.
06 Dodge Quad cab Cummins 4x4 Auto,SLT Thunder Road
07 Sierra 26FBSP
04 FXDL Harley
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LITEPHIL
AZ
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Doubt there is an ABS wheel speed sensor issue since that will trigger a code and an ABS light on.
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Turtle n Peeps
California
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LITEPHIL wrote:Its important to determine weather the brakes faded or the master bypassed. If the brakes faded the pedal would still be hard but you need much more effort. You can usually smell them if they faded. If the master went out you can usually sit at a stop and just sort of push the pedal a little and ease up and then back down and you can most of the time work it down and verify an issue BUt the newer dual masters will trigger the light if the presure between the front and rear chamber are different. I would guess you over heated them. Use your gears and slow down.
Swampyz this is exactly what I was trying to tell you. LITEPHIL did a much better job of putting it in words than I did.
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overw8chevy
florida
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Joined: 03/24/2010
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jauguston wrote:New fluid would be a good idea. Buy the highest boiling point fluid that is appropriate for your vehicle.
In the future use a lower gear when decending a long hill so you don't have to use the brakes much at all.
Jim
I was wondering if the OP was using engine braking or not?
might have just overheated the brakes
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BenK
SF BayArea
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Joined: 04/18/2002
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Key to me is that this route/condition/etc has been done for a long time, so assume
the OP knows enough about his setup and the terrain. I also tow that
route often with both TT's and when I still had my boat. It does have
some steeps and idiot 'cars' and others towing that you have to 'try'
and avoid. That means braking often just to keep from them.
Why said it depends on how the components look when R&R'd. On that
the key is the color of the fluid. The darker it is...the more moisture
it has absorbed and holding in suspension. At some point it will
settle out a bit at the bottom of whatever (lines, cylinders, calipers
or MC)
Even changed out the MC a few years ago, it can absorb moisture quickly if there
is a break in the system seal. Plastic MC reservoirs are NOT as good as a more
solid metal container....plus the o-ring seals of most all plastic reservoirs
The ABS system for the rear shoe/drums is new to me and if there is a bypass
holding reservoir back there and the history of others having problems is also
a good one to check out.
In either case...with no loss of fluid...says to me, that the pedal piston is
either bypassed at the MC or now back there in the ABS system for the rear.
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...
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