ARB RD103 - Manual (Page 13)

3 Installing the Air Locker
11
3.1 Insuring Adequate Oil Drainage
IMPORTANT:
Some axles were manufactured with poor oil drainage between
the axle tubes and the differential housing. This can often result
in one of the axle tubes filling up with differential oil while
running. In most cases this will result in a blocked air vent which
will cause the differential housing to pressurize and expel oil
from the axle seals at the wheels or force oil into the air system
of the Air Locker, eventually expelling oil at the solenoid valve.
This is a design flaw which was corrected by most automakers in
the later releases of their axle assemblies. If no lower drainage
points are present in the differential housing then it is critical
that you modify the housing to include them.
c Inspect the differential housing for the presence of adequate
drainage in both axle tubes (refer to Fig.6.).
Figure 6.
c If no drainage exists then two slots should be created in the bearing
seat face of both axle tubes; one on the upper side of the tube, and
one on the lower side. Figure 7. shows an example of an axle
housing with no existing oil drainage.