Brake System Vacuum Source Test

Disconnect the engine vacuum hose from the power brake booster check valve.
Install a vacuum gage to the engine vacuum hose.
Start the engine and allow the engine to idle until normal operating temperatures are reached.

Check to see if the engine vacuum reading is within the specified normal engine vacuum range. See ENGINE VACUUM RANGE table.

ENGINE VACUUM RANGE

Application	In. Hg (kPa)
Vacuum Variance	14-20 (47-68)

Turn the ignition OFF.
If the engine vacuum reading is within the specified normal range, proceed to step 10 .
If the engine vacuum reading is NOT within the specified normal range, inspect the engine vacuum hose for a tight connection to the engine, collapse, deformation or contamination, cracks, cuts or dry-rot.
If any of these conditions were found with the engine vacuum hose, replace the hose, then repeat steps 2 - 4 .
If none of these conditions were found with the engine vacuum hose, then there is an engine vacuum source problem, check the engine vacuum system.
Remove the power brake booster check valve from the booster.
Install the check valve to the engine vacuum hose.
Install the vacuum gage to the check valve.
Start the engine and allow the engine to idle until normal operating temperatures are reached.
Turn the ignition OFF.
Check to see if the engine vacuum reading is maintained within the specified normal engine vacuum range. See ENGINE VACUUM RANGE table.
If the engine vacuum reading is maintained within the specified normal range, proceed to step 18 .
If the engine vacuum reading is NOT maintained within the specified normal range, replace the brake booster check valve, then repeat steps 11 - 15 .
Inspect the brake booster check valve grommet for a firm connection to the power brake booster, deformation or contamination, cracks, cuts or dry-rot.
If any of these conditions were found with the check valve grommet, replace the grommet.