should be clear.) A burnt smell or brown coloration of
the fluid is a sign of overheated oil from extra heavy use
or slipping bands or clutch packs. The unit should be
sent to the shop for inspection for possible trouble.
Not all transmission fluids are the same.
Before you add fluid, check the manufacturers
recommendations fast. The use of the wrong
fluid will lead to early internal parts failure and
Overfilling the transmission can result in fluid
foaming and the fluid being driven out through the vent
tube. The air that is trapped in the fluid is drawn into the
hydraulic system by the pump and distributed to all parts
of the transmission. This situation will cause air to be in
place of oil and, in turn, cause slow application and
burning of clutch plates and facings. Slippage occurs,
heat results, and failure of the transmission follows.
Another possible, but remote, problem is water,
indicated by the fluid having a milky appearance. A
damaged fluid cooling tube in the radiator (automotive)
or a damaged oil cooler (construction) could be the
problem. The remedy is simple. Pressure test the
suspected components and repair them as required.
After reassembly, refill the transmission with fresh fluid.
Linkage and Band Adjustment. The types of
linkages found on an automatic transmission are gear
shift selection and throttle kickdown. The system can be
a cable or a series of rods and levers. Whichever the type,
they do not normally present a problem, and preventive
maintenance usually involves only a visual inspection
and lubrication of the pivot points of linkages or the
cable. Adjustment of these linkages should only be done
according to manufacturers specifications.
If an automatic transmission is being used in severe
service, the manufacturer may suggest periodic band
adjustment. Lockup bands are always adjusted to the
manufacturers specifications after an overhaul. Bands
are adjusted by loosening the locknut and tightening
down the adjusting screw to a specified value. Then the
band adjusting screw is backed off a specified amount
of turns and the locking nut is tightened down. Not all
bands are adjustable. For example, the General Motors
turbo Hydra-Matic Model 400 does not have a band
adjustment. If the band is worn to the point where it
cannot perform its function, you should replace it.
Fluid Replacement. The Naval Construction
Force (NCF), the COMCBPAC/COMCBLANTINST
11200.1 series, recommends maintenance be performed
according to the manufacturers specifications. These
recommendations vary considerably for different makes
and models. When you change automatic transmission
fluid, read the repair manual first.
Service intervals depend on the type of use the
transmission receives. In the NCF, because of the
operating environment, more than a few of our vehicles
are subjected to severe service. Severe service includes
the following: hot and dusty conditions, constant stop
and go driving (taxi service), trailer towing, constant
heavy hauling, and around the clock operations
(contingency). Any CESE operating in these conditions
should have its automatic transmission fluid and falter
changed on a regular schedule, based on the
manufacturers specifications for severe service.
Draining the transmission can be done in three
ways. By removing the drain plug, loosening the dip
stick tube, or by removing the oil pan. Have the vehicle
on level ground or on a lift and let the oil drain into a
proper catchment device.
Oil drained from automatic transmissions
contains heavy metals and is considered
hazardous waste and should be disposed of
according to local naval station instructions.
Once the oil is drained, remove the pan completely
for cleaning. By paying close attention to any debris in
the bottom of the pan, you may able be to detect a
possible problem. The presence of a high number of
metal particles could indicate serious internal problems.
Clean the pan; set it aside. All automatic transmissions
have a filter or a screen located in the oil pan. The screen
is cleanable; the falter is a disposable type and should
always be replaced when removed. These are retained
in different ways:
retaining screws, metal retaining
clamps, or O rings made of neoprene. Clean a screen
with solvent and use low pressure air to blow-dry it. Do
not use rags to wipe a screen dry as it tends to leave lint
behind that will be ingested into the transmission
hydraulic system. Any screen with a hole in it or any
screen that is abnormally hard to clean should be
Draining the oil from the oil pan of the transmission
does not remove all of the oil: the process is completed
by draining the oil from the torque converter. To do this,
remove the torque converter cover and remove the drain
plug if the converter is so equipped. (Most modern