Master cylinder replacement and brake woes, F350
Doctor John
and immediately had to do brake work on it as the brakes did not enough
stopping power and the ABS light came on even after replacing the rear ABS
sensor (there is only one ABS sensor on this truck). I replaced all 4 disk
brake assemblies (pads plus new calipers from NAPA), bled repeatedly running
two quarts of new DOT 3 synthetic fluid through the system. The old brakes
were in bad condition - calipers stuck, pads worn, but the rotors were not
significantly grooved and I did not replace the rotors. The brakes were
somewhat better after this, but still wouldn't hold the truck well on a hill
with a load and the ABS light still came on after driving about 1/10 mile.
I left the truck sitting for a couple months during the winter here in
Colorado, and when I went to use it the brakes went to the floor and only
worked marginally after pumping them up a few times. Brake fluid level was
full. So, I replaced the master cylinder with a Ford rebuilt cylinder from
CarQuest, bench bled the new master cylinder before installing and ran
another couple quarts of fluid through the system bleeding all four wheels
(RR, LR, RF, LF). So now, the brakes are soft but are better, the ABS light
STILL comes on, and now the brake light comes on, as if its out of brake
fluid (brake fluid level is topped off). I think the brake fluid level
float got bumped off track when I removed the reservoir and installed it on
the new master cylinder, but poking a rod around the float area didn't
correct the problem. How do you unstick this float? Also, brakes are still
soft and I wonder if I got all the air out of the system - any ideas on how
to bleed this system? Lastly, the ABS warning light has got me stumped -
again, ideas are much appreciated. Thanks
John
squeek
squeek
Doctor John
I am going to have this done again (the first garage, Fort Collins 4X4,
charged me $100 to run the diagnostics! so I'm looking for another repair
shop which can do this). My main concern is the soft brake pedal and the
brake light indicator. Thanks for the reply.
John
"squeek" <aco...@siue.edu> wrote in message
news:1143430901....@j33g2000cwa.googlegroups.com...
squeek
poblem other than that i don't know exept to laeve the truck to set
more then try to rebleed the breaks we had trouble with my dads 55 we
had to leave it set all summer so the breaks would have the air settle
out on its own up in the master the nwe rebleed the breaks and then
they were fine after that.
Whitelightning
"Doctor John" <nospamplease.> wrote in message
news:wtydnfku179...@trueband.net...
I don't know if the rules have changed but when I did this for a living, we
were told by GM, and Bosch reps not use silicone based brake fluids in anti
lock brake systems. The fluid foams from the surging that goes on in an
antilock system.
On bleeding, try lightly rapping the caliper housings with the HANDLE of a
small hammer, then open the bleeders and let gravity bleed a few seconds,
repeat three or four times. It knocks air bells loose from the inside
surfaces. I do the same thing to the master cylinder when bench bleeding
if I can't get plugs instead of the hose adaptors that come with most of
them. Pump a few times and then rap a few times, keep doing until no more
bubbles come out of compensating ports in master cylinder resovior.
Also is this a four wheel system or rear wheel antilock system? I ask
because there have been problems with the RWABs valve bypassing, it mimics
the way a bad master cylinder feels.
If you unplug the connector at the reservoir does the brake light go out?
Are the tires and wheels stock size? Antilock brakes work by comparing
wheel rpm to vehicle speed, via the wheel sensors and vehicle speed sensor.
The system expects to see X rpm at Y speed. The system can be recalibrated
by the dealer.
Carquest sells A1 Cardone reman products, which I have always found to be of
questionable quality. And while NAPA brake linings, calipers, wheel
cylinders etc are pretty good, their master cylinders leave a bit to be
desired. Raybestos, or Wagner are always my choice for American, and Beck
Arnely for foreign, and if the master is aluminum, I wont install
rebuilts/remans, only new masters. How do you hone an aluminum bore smooth?
From a horror job, Caddy Seville, guy let his betrothed use while he was
deployed for Desert Storm, went round and round trying to get decent pedal 4
wheel disc, staring dejectedly at master after three days, partner pushed
brake pedal, master and booster assembly moved, "Girlfriend" had
"companion" replace the booster, he didn't put all the bolts back in.
And I have never driven anything with four wheel disk that felt as good
pedal wise as a disc/drum combo, not chevy, ford, nor porsche, jag, rolls
royce, or lotus.
Whitelightning
MGH
F350 crew cab two wheel drive. New everything rotors, drums, shoes,
calipers and including the master cylinder. When test drive I had soft
brake pedal with excessive amount of travel. There is a service bulletin
which indicated the original 95 master cylinder volume size could result in
excessive brake pedal travel and should be replaced with a 96 master
cylinder. This was done and for the most part have eliminated the pedal
travel
MGH
"Doctor John" <nospamplease.> wrote in message
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Doctor John
shown your knowledge on this group, and I sure appreciate it. I will try
the bump and bleed method you suggest - I've have also heard you can have a
garage do a "power bleed" - is this worth it? I hesitated to use a rebuilt
master - I had a new one on hand, but after removing the old MC I found the
new one had a different reservoir rear port size and the only one I could
find immediately in my nearby town in stock was at CarQuest - it was a mad
scramble to get the truck back together before a winter storm blew in. At
least the rebuilt was a genuine Ford, and it doesn't go to the floor
anymore. The wheels are all the same brand and are stock size and the truck
is a 4x4 with dually rear tires. I think I finally got the float indicator
fixed by whacking firmly on the side of the reservoir. The brakes still
just don't feel like they grip well. If I mash the pedal with all I've got,
I can still get the truck to move forward in low range when I goose the
gas - maybe this is normal and I'm just used to a firmer pedal and more
holding power. The ABS light still comes on after driving a few feet - I
think if it was due to fluid foaming it would take more than this distance
to get the effect to occur, but I could try changing the fluid out. Thanks
again, and please keep the ideas coming.
John
"Whitelightning" <white.li...@verizon.net> wrote in message
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