Brake problem
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Lead Driver
Joined: Mar 2008
Posts: 7,174
Likes: 377
From: Near Los Angeles
Well, yep, I hate to admit it, but after changing the master, soft lines, and rebuilding the front calipers, I am still having the same problem.
Every morning I start it up and drive about 4 miles before I can feel the free play in the pedal becoming less, until it is gone completely, and the brakes start dragging w/o touching the pedal.
I don't believe the prob. to be fitment, otherwise it wouldn't have taken six months for this problem to arise.
I have checked about everything, and really don't know what to do next.
I've never heard of a hydro unit suddenly start pushing by itself, but I'm starting to think that is what is happening.
Every morning I start it up and drive about 4 miles before I can feel the free play in the pedal becoming less, until it is gone completely, and the brakes start dragging w/o touching the pedal.
I don't believe the prob. to be fitment, otherwise it wouldn't have taken six months for this problem to arise.
I have checked about everything, and really don't know what to do next.
I've never heard of a hydro unit suddenly start pushing by itself, but I'm starting to think that is what is happening.
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Lead Driver
Joined: Mar 2008
Posts: 7,174
Likes: 377
From: Near Los Angeles
Tuned
Joined: May 2008
Posts: 334
Likes: 41
yea, I'm with you on only fixing what's known to be broke. Maybe someone can chime in on how to determine when the hydroboost needs rebuilding. the rebuild kit I purchased was only $30 or so. it seems this is one of the last things in the brake system left untouched.
Thread Starter
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Lead Driver
Joined: Mar 2008
Posts: 7,174
Likes: 377
From: Near Los Angeles
It seems to usually act up on the first drive of the day. By the time I have gone 3-4 miles the brakes are starting to drag. Today it happened, and I shut it off for ten minutes, then it drove fine the rest of the day. Go figure.
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
Hi Kevin, I did some reading about hydroboost, and it sounds like your not the only one with hydroboost brakes coming on by themselves-
99 F350 Super Duty Brake Issues - Diesel Forum - TheDieselStop.com
brake problem: please help im stuck in Price UT towing a load. [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums
sounds like the guy in post #8 here is having almost exactly the same issue as you: Brakes...very spongy pedal... - Diesel Forum - TheDieselStop.com
From what those guys are saying, it could be either the master cylinder, or the booster unit that's bad (or some other stuff on ABS vehicles.) Since you've got a brand new master cylinder on it, I'd suspect the booster. Did you re-build the booster before you put it on?
Sam
99 F350 Super Duty Brake Issues - Diesel Forum - TheDieselStop.com
brake problem: please help im stuck in Price UT towing a load. [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums
sounds like the guy in post #8 here is having almost exactly the same issue as you: Brakes...very spongy pedal... - Diesel Forum - TheDieselStop.com
From what those guys are saying, it could be either the master cylinder, or the booster unit that's bad (or some other stuff on ABS vehicles.) Since you've got a brand new master cylinder on it, I'd suspect the booster. Did you re-build the booster before you put it on?
Sam
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Lead Driver
Joined: Mar 2008
Posts: 7,174
Likes: 377
From: Near Los Angeles
I did not rebuild the booster. It is a top-of-the-line j/y booster, 1994 Astro Van. I guess I should look into rebuilding, since it is the one piece in the system that is not new or rebuilt.
I would have done so earlier if the unit were not a modified and so much fun to install/remove. I've never done one, so it could be fun.
I would have done so earlier if the unit were not a modified and so much fun to install/remove. I've never done one, so it could be fun.
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Tuned
Joined: May 2008
Posts: 334
Likes: 41
I found it pretty painless to do the rebuild. There is one step on myinstructions that said to cut the arm off to allow for the unit to be fully dismantled, but I didn't do that and worked around it in that state (it was tricky getting new orings on the shaft, but I was very careful). You're probably looking at a few hours work. Mine is out of an F450 though.
Thread Starter
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Lead Driver
Joined: Mar 2008
Posts: 7,174
Likes: 377
From: Near Los Angeles
Hi Kevin, I did some reading about hydroboost, and it sounds like your not the only one with hydroboost brakes coming on by themselves-
99 F350 Super Duty Brake Issues - Diesel Forum - TheDieselStop.com
brake problem: please help im stuck in Price UT towing a load. [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums
sounds like the guy in post #8 here is having almost exactly the same issue as you: Brakes...very spongy pedal... - Diesel Forum - TheDieselStop.com
From what those guys are saying, it could be either the master cylinder, or the booster unit that's bad (or some other stuff on ABS vehicles.) Since you've got a brand new master cylinder on it, I'd suspect the booster. Did you re-build the booster before you put it on?
Sam
99 F350 Super Duty Brake Issues - Diesel Forum - TheDieselStop.com
brake problem: please help im stuck in Price UT towing a load. [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums
sounds like the guy in post #8 here is having almost exactly the same issue as you: Brakes...very spongy pedal... - Diesel Forum - TheDieselStop.com
From what those guys are saying, it could be either the master cylinder, or the booster unit that's bad (or some other stuff on ABS vehicles.) Since you've got a brand new master cylinder on it, I'd suspect the booster. Did you re-build the booster before you put it on?
Sam
Thank you for that. All this time I never thought it could be the hydro, so I never looked into rebuilding one. Now I will. First, however, I need to ck the hydro push arm. When I put on the new master it seemed to be engaging the m.c. piston when I still needed to move the master 1/4" toward the fire wall.
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