BENDIX BW1399 User Manual

Turn off engine. Make 10-15 full brake applications to get rid

of all vacuum. Make and hold a full brake application and

observe gauge at wheel. Pressure valve is not important.

Watch for a pressure drop.

Pressure rises instantly

and remains constant while

brakes are held applied.

Pressure rises instantly but

begins to fall while brakes

are held applied.

Hydraulic system okay.

Vacuum leakage most likely

causing the pressure drop.

Vacuum system probably

not causing pressure drop.

Hydraulic leakage most

likely causing pressure

drop.

Shut off engine and note any change in vacuum gauge. The

following are maximum acceptable leakage limits:

1. Vacuum system with separate vacuum reservoir; a drop

of no more than 2" HG in 60 seconds.

2. Vacuum system without separate vacuum reservoir; a

drop of no more than 2" HG in 15 seconds.

Leakage is okay. Proceed to

Step 3 and continue testing.

Leakage NOT okay. To 

pinpoint leakage source,

reinstall gauge at positions

indicated in Figure 3 and

retest at each position.

Begin at position #3 to test

hose between check valve

and vacuum source. Repair

or replace components

ahead of gauge when

unacceptable leakage is

noted. Continue testing

until leakage checks okay

at position #1.

Leakage is okay. Proceed to

Step 3 and continue testing.

Perform Phase III Vacuum

System Checks.

Perform Steps 1, 4, 5 of

Phase I Visual Inspection

again. Return to beginning

of Step 3 and retest.

PHASE III – VACUUM

SYSTEM TESTS

1. Remove vacuum line from booster control valve section and

install a vacuum gauge with a range of 0-30 inches of mercury

in the end of the line. (Refer to Figure 3 Gauge Position #1.)

2. Start engine and allow to idle for several minutes to allow vacu-

um gauge reading to stabilize, then read gauge. Vacuum should

be a minimum of 16 inches of mercury. Record gauge reading

here _________________" HG for use later.

There are two possible gauge results; proceed to the correct head-

ing and continue testing.