TOYOTA PREVIA 91-97 REPAIR MANUAL

DRIVE TRAIN 7-13

Fig. 41 The clutch accumulator is located near the carbon canis-

ter

Fig. 42 Have an assistant pump the clutch pedal several

times..

Hydraulic System Bleeding

» See Figures 42 and 43

-»lf any maintenance on the clutch system was performed or the
system is suspected of containing air, bleed the system. Use care;
brake fluid will remove the paint from any surface. If the brake fluid
spills onto any painted surface, wash it off immediately with soap
and water.

1. Fill the clutch reservoir with brake fluid. Check the reservoir level fre-
   quently and add fluid as needed.


2. Connect one end of a vinyl tube to the bleeder plug on the slave cylinder
   and submerge the other end into a clear container half-filled with brake fluid.


3. Slowly pump the clutch pedal several times.


4. Have an assistant hold the clutch pedal down and loosen the bleeder
   plug until fluid and/or air starts to run out of the bleeder plug. Close the
   bleeder plug while the pedal is held to the floor.

~Do not allow the pedal to rise back up while the bleeder is still
open. If this happens, it will allow air to re-enter the slave cylinder
and cause the clutch system not to work properly.

5. Repeat Steps 2 and 3 until all the air bubbles are removed from the
   system.


6. Tighten the bleeder plug when all the air is gone.

AUTOMATIC TRANSMISSION

Fig. 43 ... while he is holding the pedal down, loosen the

bleeder plug until fluid runs out

7. Refill the master cylinder to the proper level as required.


8. Check the system for leaks.

Understanding the Automatic Transmission

The automatic transmission allows engine torque and power to be trans-

mitted to the rear wheels within a narrow range of engine operating speeds.

It will allow the engine to turn fast enough to produce plenty of power and

torque at very low speeds, while keeping it at a sensible rpm at high vehicle

speeds (and it does this job without driver assistance). The transmission

uses a light fluid as the medium for the transmission of power. This fluid

also works in the operation of various hydraulic control circuits and as a

lubricant. Because the transmission fluid performs all of these functions,

trouble within the unit can easily travel from one part to another. For this

reason, and because of the complexity and unusual operating principles of

the transmission, a very sound understanding of the basic principles of

operation will simplify troubleshooting.

TORQUE CONVERTER

I See Figure 44

The torque converter replaces the conventional clutch. It has three func-

tions:

1. It allows the engine to idle with the vehicle at a standstill, even with
   the transmission in gear.


2. It allows the transmission to shift from range-to-range smoothly,
   without requiring that the driver close the throttle during the shift.


3. It multiplies engine torque to an increasing extent as vehicle speed
   drops and throttle opening is increased. This has the effect of making the
   transmission more responsive and reduces the amount of shifting required.
   The torque converter is a metal case which is shaped like a sphere that