wheels should be chocked and the brakes set during the
adjustment varies for different vehicles; therefore, the
technical manual for the vehicle should be consulted
oil level check.
for this adjustment.
OIL PRESSURE CHECKS.--Oil pressure
Throttle linkage adjustment is the adjustment of
checks are performed to determine if sufficient
the control rod from the throttle valve on the
pressures are available to the operating units to cause
transmission to the accelerator linkage at the engine
them to operate properly. The main thing in making oil
carburetor. This adjustment is very difficult to set until
pressure tests is to use a pressure gauge that will
the engine has been properly adjusted, because the
handle, without damage, the pressures being tested.
engine speed affects the throttle valve pressure.
Another important point is to be sure of the pressure
check point on the transmission, as each hydraulic
Band adjustments are made periodically as
circuit may require a different pressure for a certain
specified by the manufacturer. Some transmissions
allow band adjustments from the outside of the
transmission case, while others require removal of the
oil pan before the bands can be adjusted. In all cases,
for trouble-free operation the bands should be adjusted
at the time interval and by the procedures specified by
require very little maintenance. However, oil seals and
g a s k e t s m a y f a i l o c c a s i o n a l l y, t h u s r e q u i r i n g
maintenance. For maintenance other than oil leaks, the
fluid coupling or torque converter is replaced as a unit,
if it is a sealed unit. If it is not a sealed unit, limited
When checking an automatic transmission, most
repair and parts replacement may be authorized.
manufacturers suggest you start with the oil level in the
reservoir. Next, make an oil pressure check on the
If maintenance requires the disassembly of a unit,
various hydraulic circuits. For example, to check the
it should be thoroughly inspected. In most cases all
main line or regulated oil pressure, connect a pressure
seals and gaskets should be replaced with new ones
gauge to the specified check point on the transmission
during reassembly. Components of the unit, such as a
and operate the engine at the specified rpm with the
pump, turbine, stator, one-way clutch, and so on,
transmission in neutral (N). This test can be used to
should be replaced if they show signs of excessive wear
check the condition of the pressure regulator or pump.
or are defective.
OIL LEVEL CHECKS.--This check is made to
determine if there is sufficient oil in the reservoir to
supply the demands of the torque converter or fluid
The range section (planetary sets) of a
coupling plus the other needs of the transmission. To
disassembled transmission should be inspected for
make the test, most manufacturers recommend
chipped teeth, wear patterns, and worn support
operating the engine and transmission until they have
bearings. The thrust washers should also be inspected,
achieved the normal operating temperature. Usually,
and replaced if they show signs of excessive wear. If
when the engine temperature is normal, so is the
the bearings are defective, or any member of the
transmission oil temperature.
planetary set is defective, replace the gear set.
Before taking a reading of the oil level, operate the
transmission through its ranges and then place the
selector in the N position. Remove the bayonet gauge
(dipstick) from the transmission and check to see if the
A clutch is usually used to hold two members of a
oil is at the right level. If the level is low, fill it with the
planetary gear set, and a servo band is used to hold one
correct type of oil to the correct level. If the level is too
member. Normally, a defective clutch or servo
high, it should be drained until the correct level has
(slippage) can be detected by road testing the vehicle.
The manufacturer's recommendations should be
followed for road testing a specific vehicle. If a clutch
D i ff e r e n t t r a n s m i s s i o n m a n u fa c t u r e r s m a y
or servo is defective, it normally will require
recommend different positions for the shift lever
transmission removal from the vehicle to perform
during this check. In case the manufacturer
recommends that the lever be in the D position, the
maintenance (except for servo band adjustment).