freightliner Argosy COE 2011, Maintenance Manual

Page: 109 / 193

33–11 Steer Axle Hub Cap Vent
Plug Inspection
General Information
As a function of their design, hubcap vent plugs will
on occasion exhibit signs of hub oil on their exterior
surface. Depending on environmental conditions
and/or age of the plug, the amount of oil present can
vary. This is a normal result of the venting process
due to pressure increase within the hub cavity. For
an example of normal vent plug appearance, see
Fig. 10 .
A vent plug can wear or be damaged and cause ex-
cessive leakage, or allow water to enter the hub and
contaminate the oil. For examples of a leaking vent
plug, see
Fig. 11 and Fig. 12 . Evidence of a leaking
vent plug may appear as;
•
Oil splatter around the wheel
•
Gooey/gummy oil around the vent plug purge
point
•
Hub/plug area is dirty, and water contaminated
oil in the hub.
•
Hub/plug area is clean, but there is water con-
taminated oil in the hub. (pressure washing is
the most likely cause)
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A
B
1
1
A Upper View, LH Side B Lower View, LH Side
1. Grease Fitting
Fig. 7, Grease Fittings, Detroit Axles
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Fig. 8, Kingpin Grease Exit Points, Detroit Axles
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1
2
NOTE: No grease should emit from the tie-rod boot. If
grease emits from the tie-rod boot, the boot is dam-
aged.
1. Grease Fitting 2. Boot
Fig. 9, Grease Fitting and Boot, Detroit Axles
Front Axle
33
Century Class Trucks Maintenance Manual, August 2017
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