Legacy GT LTD Sedan AWD F4-2.5L SOHC (2001)
Vacuum Brake Booster: Testing and Inspection
Using Gauges
INSPECTION
OPERATION CHECK (WITH GAUGES)
CAUTION: When checking operation, be sure to securely apply the hand brake.
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Checking with gauges
Connect gauges as shown in Figure. After bleeding air from pressure gauges, proceed to each check.
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Air tightness check
1. Start engine and keep it running until a vacuum of 66.7 kPa (500 mm-Hg, 19.69 inch-Hg) = point A is indicated on vacuum gauge. Do not
depress brake pedal.
2. Stop engine and watch the gauge. If the vacuum drop range is less than 3.3 kPa (25 mm-Hg, 0.98 inch-Hg) within 15 seconds after stopping
engine, brake booster is functioning properly. If defective, the cause may be one of those listed below.
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Check valve malfunction
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Leak from vacuum hose
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Leak from the shell jointed portion or stud bolt welded portion
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Damaged diaphragm
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Leak from valve body seal and bearing portion
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Leak from plate and seal assembly portion
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Leak from poppet valve assembly portion
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Loaded air tightness check
