S15/T15 Sonoma P/U 2WD V6-4.3L VIN X (1998)
Brake Master Cylinder: Description and Operation
The master cylinder is designed for a brake system with low drag calipers. In addition to the standard master cylinder functions, the JM3 system includes
a quick take-up feature. The quick take-up feature provides a large volume of low pressure brake fluid to the wheels upon the initial brake application.
The large volume of brake fluid overcomes the clearance created by the brake caliper pistons.
The reservoir and cap are made of plastic. The cap screws onto the top of the reservoir. Keep the master cylinder reservoir properly filled with brake
fluid. This ensures adequate reserve brake fluid and prevents air from entering the hydraulic system. Do not over fill the reservoir. An over filled
reservoir will not allow the needed brake fluid expansion caused by heat absorbed from the brakes and the engine.
Master Cylinder Identification
Identifying information is stamped into the front surface of the body of the master cylinder.
The Delphi master cylinder has the following information:
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The first two digits identify the build code.
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The third digit indicates the year the master cylinder was built (Example: 7 means 1997).
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The last digits indicate the day the master cylinder was built (Example: 271 means the 271st day of the production year).
