Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSBUICK1987CENTURY CUSTOM, 4D SEDAN, 2.5 RREPAIR AND DIAGNOSIS (SINGLE PAGE)TRANSMISSIONAUTOMATIC TRANSOVERHAUL - 440-T4/4T60 & 4T60-ETESTINGHYDRAULIC PRESSURE TESTSNOTES
1987 Buick Century Custom, 4D Sedan, 2.5 R
Hydraulic Pressure Tests: Notes
1987 Buick Century Custom, 4D Sedan, 2.5 RSECTION Notes
CAUTION:
Parking and service brakes must be applied throughout hydraulic pressure test. Total time for testing with vehicle in any driving gear should not exceed 2 minutes.
- Before performing hydraulic pressure tests, check fluid level and condition. Check Throttle Valve (T.V.) and manual control linkages for correct adjustment, and ensure engine is properly tuned.
- Connect tachometer to engine, hand-held vacuum pump to vacuum modulator and oil pressure gauge to line pressure test port. See Figure. Test for correct line pressure at specified engine RPM. See Figure-Figure.
NOTE:
Hydraulic pressure is controlled by pump output and regulated by pressure regulator valve. Line pressure is boosted by reverse boost valve when selector is in "R" and "D1" positions. Line pressure should increase with throttle opening due to decrease in engine vacuum to vacuum modulator.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.