Transmission Fluid Cooler
Transmission and transaxle operation causes the fluid
to get very hot. This heat must be removed to keep the
fluid from breaking down and to keep the holding mem-
bers from becoming so hot that they begin to slip and burn.
To accomplish this, the transmission fluid is pumped
through metal lines to a transmission fluid cooler in the
vehicle’s radiator. In the cooler, the fluid gives up its heat
to the engine coolant and then returns to the transmission.
On most transmissions, the fluid goes directly from the
torque converter to the cooler. This is because the torque
converter produces most of the heat generated by the
transmission, especially at low speeds. Figure 1-38 shows
the path of transmission fluid through the cooler and back
to the transmission. A few vehicles use a separate direct-
air cooler. Direct-air coolers are also available as add-on
units. A direct-air cooler is a single tube bent into one or
more U-shaped forms. These forms are surrounded by fins.
The direct air cooler is installed ahead of the radiator. Air
passing through the cooler removes heat by direct contact.
Transmission Fluid Filter
All transmissions and transaxles produce some metal
shavings and particles of friction material as they wear.
Additionally, transmission fluid breaks down from heat and
age. The aging fluid develops solid deposits, which circu-
late in the fluid. The metal shavings, friction material par-
ticles, and solid deposits must be removed from the fluid
as it circulates through the hydraulic system. Failure to
remove these impurities can result in sticking transmission
control valves and worn parts.
The transmission fluid filter catches and removes
these impurities as the fluid passes through it. Some filters
are fine mesh screens. Most filters, however, are made of
felt or filtration paper enclosed in a metal or plastic hous-
ing. The filter is always installed on the suction side of the
pump so it can remove impurities before they reach the
pump and other hydraulic system components. The filter is
located in the bottom of the transmission or transaxle so it
is always covered by transmission fluid, Figure 1-39. A few
transaxles have two filters. Filters should be changed as
part of periodic transmission or transaxle maintenance.
28 Automatic Transmissions and Transaxles
Figure 1-32. Gaskets are used throughout every transmission and transaxle. Some gaskets seal internal pressure passages. Others
keep fluid from leaking out of the unit. (General Motors)