Escort L4-122 2.0L SOHC (1997)
Vacuum Brake Booster Check Valve: Testing and Inspection
1. Remove the vacuum booster hose from the power brake booster.
2. Apply 57.3 kPa (17 in-Hg) of vacuum to the vacuum booster hose. Does the vacuum leak off after ten minutes?
YES - replace the check valve and hose if it is damaged.
NO - the check valve is OK.
3. Reinstall check valve. Be careful not to push grommet into booster.