Brake master cylinder

1996 CHEVROLET TRUCK
244,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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TRACY JOYCE OLSON
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I blew a brake line last night, replaced line.bled brakes from master cylinder, brakes very squishy.
Brakes were bled from master cylinder.they were squishy before but now it is worse. when the reservoir ran out from the blown brake line It was steamy.it was out of fluid for awhile. I kept it topped off until I got home, about fifteen miles. brakes go all the way to floor, but still stop it. not very good though. could I have blown the master or could it be because they were not bled correctly?
Mar 16, 2017 at 11:28 AM
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CARADIODOC
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Both. If the truck has four wheel anti-lock brakes, you may need a scanner to open some valves so air can be expelled from some chambers during bleeding. Crud and corrosion build up in the lower halves of the bores in the master cylinder where the pistons do not normally travel. When the brake pedal is run all the way to the floor, either during bleeding, or when surprised by a sudden leak, the lip seals are run over that corrosion and can be torn. That results in a slowly-sinking brake pedal, and that often doesn't show up for two or three days.

Master cylinders are most commonly damaged from that crud when the hydraulic system is pedal-bleed with a helper, by do-it-yourselfers. To avoid this problem, professionals rarely pedal-bleed, and if they do, they do not run the pedal more than half way to the floor. We typically prefer to gravity-bleed. That requires no special tools and no helper.
Mar 16, 2017 at 2:48 PM
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STEVE W.
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Have you had any luck repairing this problem ??
Mar 20, 2017 at 8:27 PM
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