Sometimes It Stops
courtesy of Bob, The Auto Answer Man
I have a 1989 Chevy 1/2 ton truck with an inconsistent brake pedal. Sometimes the pedal is firm high and other times it goes halfway to the floor before firming up. The master cylinder has been replaced, the rear wheel cylinders have been replaced, the disc pads and rear shoes have been replaced and the system has been bleed three times until the fluid is clean. Got any ideas.
You replaced just about everything, but have you checked the brake hoses? If they are old and swelling, then your low pedal could be due to that. As you step on the brakes, the hose swells instead of sending pressure to the caliper or drums. Also, have you checked the proportioning valve?
Bob, The Auto Answer Man
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