Suburban 3/4 Ton 4WD V8-305 5.0L (1986)
Brake Bleeding: Fundamentals and Basics
BENCH BLEEDING
Why
A master-cylinder will develop little or no pressure if air is trapped in cylinder bore. Normal brake bleeding will not remove air trapped within
the master-cylinder.
How
Clamp the master-cylinder securely in a vice. It is usually best to clamp the side of the vice onto the flat surface that is used to secure the
master-cylinder to the brake booster.
There are two basic methods for bleeding master-cylinder, one utilizes stroking the master-cylinder to expel air from the cylinder bore while
the other utilizes a large syringe to backflush fluid from the outlet ports to the reservoir.
Stroking
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Fill the master-cylinder with clean brake fluid.
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The brake line fittings on the master-cylinder should be capped or plugged.
NOTE: Special "bench bleeding" plastic fittings are available which allow for recirculating the brake fluid back into the reservoir.
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Using a dull object, slowly stroke the master-cylinder piston, air and brake fluid will be expelled from the brake line fittings. Prior to
releasing the piston plug or cap the outlet ports.
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Repeat this procedure 8-10 times or until no air is emitted from the outlet ports.
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When finished, cap the outlet ports and install the master-cylinder.
Syringe
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Fill the syringe (one especially designed for brake bleeding) with clean brake fluid.
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Insert the end of the syringe into one of the outlet ports on the master-cylinder.
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Slowly compress the syringe and back flush the brake fluid through the master-cylinder.
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A combination of air and brake fluid will be emitted from the inlet port in the fluid reservoir.
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Repeat this procedure until only brake fluid is emitted into the reservoir.
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Cap the outlet ports and install the master-cylinder.
