Clutch issue ?

[jondee86]

There is a bit of conflicting information here about the symptoms and
exactly what might be causing this (or these) problems. The shotgun
approach may get to the bottom of the mystery, and so I will throw in
something that fits some of the symptoms

Here is a generic clutch master cylinder diagram that I believe represents
what is found inside the Aisin master cylinder.



When the clutch pedal is operated the piston moves forward closing off
the vent port and applying pressure to the slave cylinder. When the pedal
is released, the piston retracts and uncovers the vent port so that any
excess fluid can return to the reservoir. So far so good = normal operation.

However, if the clutch pedal has been adjusted to raise the pedal and
there is no longer adequate freeplay, the piston may not be able to retract
far enough to uncover the vent port. When this happens, it is possible for
extra fluid to pass by the high pressure seal and enter and become trapped
on the (now sealed) high pressure side of the piston.

Under these circumstances the fluid volume is slowly "ratcheted" up as the
pedal is operated, resulting in the slave piston creeping forward and exerting
pressure on the cltch fork. This will reduce the clamping load exerted by the
clutch, bringing it ever closer to slipping. Eventually, the clutch will be unable
to transmit sufficient torque to drive the car and will burn up.

Simple enough to get under the dash and check the adjustment of the clutch
pedal linkage according to the Toyota Service Manual. Alternative check is to
get under the car and open the slave bleeder screw and see if fluid under
pressure squirts out. If there is trapped pressure the slave will also be pushing
hard against the fork without any freeplay.

Cheers... jondee86