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losing brake fluid

losing brake fluid

Postby Toasted_311 [OP] » Jan 28 2012, 9:05am

My 05 GMC Sierra 4.8 ext cab front rotor/rear drum truck with 92k is slowly losing brake fluid. Not lowering the level as the pads wear but leaking somewhere. The front lines, calibers, master cylinder and all rear lines etc are all dry.
Truck just got new front hubs, rotors, pads 5-6 k ago, i've had both ends down 3x now looking for a leak and can't find anything at all wet. It takes about 2-3 weeks for it to get low enough to trigger the brake light under heavy stopping or heavy acceleration.
I bled/flushed the entire system 6 months ago, it was doing this before that though.

I am thinking about replacing the rubber brake hoses with steel braided if I can find a kit but does anyone have an idea about where the fluid has to be going?

thanks
I've done so much with so little for so long, that I can do anything with nothing
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Re: losing brake fluid

Postby ASTE25 » Jan 28 2012, 9:31am

Have you checked the rear wheel cylinders? Does the pedal always feel firm? The only place I can think of it leaking and not being visible is out the back of the master cylinder bore and into the vacuum booster (where it could go into the intake and be burned through the engine).
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Re: losing brake fluid

Postby Toasted_311 [OP] » Jan 28 2012, 9:41am

Yes, all rear brake comp are dry as is all the front. No different feel in the pedal either. I have noticed smoke from time to time under hard accel...no oil lose so I take it that's the brake fluid burning off?
I've done so much with so little for so long, that I can do anything with nothing
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Toasted_311
Automotive Technician
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Combustion on 3 pistons [L2]
Combustion on 3 pistons [L2]
Posts: 313
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Joined: Jan 27 2012, 11:45pm
Years of membership: 2 years of membership2 years of membership
Location: West Memphis, AR
Year: 2014
Make/Model: Chevrolet Silverado
Extra Info: 5.3 double cab
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Re: losing brake fluid

Postby ASTE25 » Jan 28 2012, 12:01pm

Possibly. I'd suggest removing the master cylinder and seeing if there is evidence of fluid leaking out the rear of it and into the booster.
Jordan
ASTE25
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