SB-16-NA-117

File in Section:
Service Bulletin
-
Bulletin No.:
16-NA-117
Date:
April, 2016
INFORMATION
Subject:
Information Regarding Magnetic Drain Plugs
Attention: This Bulletin also applies to any of the models that may be Export vehicles.
Brand:
Model:
Buick
Cadillac
Chevrolet
GMC
All GM
Passenger
Cars and
Trucks
Model Year:
VIN:
from
to
from
2009
2017
Engine:
Transmission:
All
All
to
Purpose of Magnetic Drain Plugs
Magnetic drain plugs in drive axles, transmissions and
transfer cases are designed to attract metallic particles
generated during normal operation and prevent them
from passing through the gears or bearing.
When inspecting metallic particles on a plug magnet,
it’s important to determine the size and source.
Important: Inspection of the drain plug does not
constitute a diagnosis, it should be used to determine if
further investigation is required.
Normal Condition
4488023
Fine metal particles, as illustrated above, are normal
and are the result of internal component wear, which
can shed fine metallic particles at a steady rate.
Metal shavings, which are often remnants from the
housing machining process, may adhere to the plug
magnet. These shavings are not detrimental to
component operation and do not require component
replacement.
4488022
During service repairs and maintenance, inspect the
drain plug for large metal deposits. Small metal flakes
and fine metal dust on the plug magnet are considered
normal.
Copyright 2016 General Motors LLC. All Rights Reserved.
Page 2
April, 2016
Not Normal Condition
Fluid Conditions
4488026
Fragments from bearings and gear teeth indicate
component damage that is not considered normal.
Components should be inspected for damage and
repaired as needed.
Version
Bulletin No.: 16-NA-117
The color of the fluid can be an indicator of
contamination; however, some colors can be easily
confused with the normal color of some fluids.
New fluid is usually red or light brown. With time and
miles, used fluid often turns black. This is a result of the
normal chemical process that occurs as the additive
package in the fluid degrades. The black color does not
indicate that the fluid’s useful life has been exhausted.
When a fluid is a milky brown color, it may indicate that
the fluid is contaminated with significant moisture. The
fluid should be changed.
Water contamination of the axle lube also creates
significant odor and forms corrosive conditions that will
cause internal components of the axle to corrode.
Milky-colored fluid combined with rust particles is a sign
of moisture contamination either from submersing the
axle vent, a pinched or misrouted vent hose, or a failed
seal that is allowing moisture to enter the axle.
Under 5000 miles (8,000 km) of operation, hypoid axle
lube may appear tinted and have a whitish or yellow
appearance from the gear marking compound used in
the production of the axle.
1
Modified
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
WE SUPPORT VOLUNTARY
TECHNICIAN
CERTIFICATION