Basic Test
- With engine off, depress and release the brake pedal several times to purge all vacuum from the power brake booster.
- Depress and hold the pedal with light effort (15-25 lbs. pressure), then start the engine.
- Disconnect the vacuum hose on the side of the vacuum check valve that leads to the speed control, then connect a vacuum gauge to the open vacuum port on the valve.
- Start the engine.
- When the engine is at warm operating temperature, allow it to idle and check the vacuum at the gauge.
- Once an adequate vacuum supply is obtained, repeat test.
NOTE:
The pedal should fall slightly, then hold. Less effort should be needed to apply the pedal at this time. If the pedal fell as indicated, see VACUUM LEAK TEST . If the pedal did not fall, continue with this test.
NOTE:
If the vacuum supply is 12" Hg. (40.5 kPa) or more, the power brake booster is defective and must be replaced. If the vacuum supply is below 12" Hg. (40.5 kPa), the hose or check valve to the booster has a restriction or leak.