Brake System Vacuum Source Test
- Remove the engine vacuum hose from the power brake booster. See Fig 1 .
- Install a vacuum gage to the engine vacuum hose.
- Start the engine. Verify the transmission is in Park or Neutral.
- Allow the engine to idle until the engine reaches normal operating temperatures.
- Check to see if the engine vacuum meets or exceeds the minimum specifications. See ENGINE VACUUM SPECIFICATIONS
.ENGINE VACUUM SPECIFICATIONS
Application Hg (kPa) Minimum Engine Vacuum 17 (57.6) - Turn ignition OFF.
- If the engine vacuum reading meets or exceeds the minimum specifications, verify the check valve operates properly.
- If the engine vacuum reading is less than the minimum specification, inspect the power brake booster pipe and hoses for the following conditions:
- Loose connection to the engine.
- Collapse, deformation or contamination.
- Cracks, cuts, dry-rot.
- Replace any defective power brake booster pipe or hose. See POWER BRAKE BOOSTER HOSE under REMOVAL & INSTALLATION.
- If none of these conditions exist on the pipe and hoses, then there is an engine vacuum source problem. Check the engine vacuum system.
NOTE:
If the engine does not produce proper vacuum, the vehicle will have driveability condition in addition to the brake assist condition.