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2003 3500hd Brake problem


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hornswagel69
User

Apr 9, 2014, 4:52 AM

Post #1 of 7 (1766 views)
2003 3500hd Brake problem Sign In

03 chevy 3500HD dually with duramax. last season went through 1 gal. of brake fluid with no apparent leaks. no lights, replaced wheel ABS sensors, when coming to a stop loose about 1 inch of pedal but does stop. not a constant problem but a severe one if failure occurs, Any Ideas?


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 9, 2014, 5:14 AM

Post #2 of 7 (1760 views)
Re: 2003 3500hd Brake problem Sign In

A gallon and you can't find it is huge! I guess either way but is this hydro boost w PS pump pressure or vacuum assist power brakes?


Gotta guess as you didn't say. I can say the loss without evidence can be sucked into a vacuum booster and probably burn it off thru vacuum hose but you should have felt lousy assist OR weaker than normal assist as it filled up.


Hydro boosted would about have to leak out and be seen?


Does this HD package give you rear drum brakes? Those can change pedal height just as the vehicle makes a complete stop just as load shifts from pulling on wheels/drums backwards to a quick forward rebound and not be part of this fluid loss. Less likely IMO if rear disc for that.


That's way too much fluid so no matter what if you can't find it send it out now! You could just loosen master cylinder mounting nuts just a bit and see fluid pour out and declare master NG if so.


Less likely is trauma or rusted out brake parts as there should be evidence. Look inside of wheels and with this take them all off anyway for up close inspection.
FYI - Brake fluid is water soluble so if wet driving a lot evidence could be washed away?


T



hornswagel69
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Apr 9, 2014, 5:41 AM

Post #3 of 7 (1753 views)
Re: 2003 3500hd Brake problem Sign In

Thanks for the quick feedback, its all wheel disc with hydro-vac. I know I should have seen fluid by now but all stays dry. GM has looked at it but cant seem to find a problem. Just looking to see if anyone else has seen this oddity out there anywhere. have pressure tested system and no leaks.. What about ABS control, a possibility?


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 9, 2014, 6:07 AM

Post #4 of 7 (1746 views)
Re: 2003 3500hd Brake problem Sign In

It's "hydro-boost" if not vacuum boost so make up your mind.


Said already a hidden spot would be behind master cylinder and just might leak to ground and not be found or might only do it unless under full or a lot of braking pressure or maybe just drip with no braking. Park on dirt or rocks by any chance? Just might not see it so easily.


If you've already told GM or any place that you've added a GALLON of brake fluid and they quit looking that's scaring me!


One other place that could be intermittent is the grommet between plastic tank and the master itself but you'd see it. OK to wash that off with plain window cleaner and make it dry right there with compressed air as needed and watch or leave a rag around it and see if it gets wet when WATER is not involved. If wet and is washes out and dries it's brake fluid. If so toss the whole master as you may not know if tank or grommet so easily and they come all new together so rules out the whole thing or should.


You shouldn't be driving this till this leak is found as up to total loss of brakes can and will happen with or without warning!


T



hornswagel69
User

Apr 9, 2014, 12:02 PM

Post #5 of 7 (1731 views)
Re: 2003 3500hd Brake problem Sign In

It is hydro-boost sorry for the confusion, used to big trucks. Thanks for the help will continue searching for the problem.


Discretesignals
Ultimate Carjunky / Moderator
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Apr 9, 2014, 5:45 PM

Post #6 of 7 (1713 views)
Re: 2003 3500hd Brake problem Sign In

 A gallon of brake fluid? wow. They need to look harder.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


nickwarner
Veteran / Moderator
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Apr 10, 2014, 12:31 AM

Post #7 of 7 (1705 views)
Re: 2003 3500hd Brake problem Sign In

Is your tech's name Magoo by chance? Anything that could drop a gallon of brake fluid in a season should be obvious. Look for bubbled paint, as you said it did this last year. Brake fluid is hell on paint and will bubble it up.






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