'01 OBW Automatic Transmission lockup

[Mike]

Hello all:

I've noticed that the automatic transmission on this Subie does not go
into torque converter lockup when the car is cold. I usually don't
drive this car often, but I noticed this since the weather has gotten
colder here (0 deg. F). Is this a "feature" on this transmission or do
I have the beginnings of a lockup solenoid or torque converter
problem? BTW - it's the 2.5 engine.

The car has 44K miles on it, just had the head gaskets replaced under
warranty.

Mike

 

[Dominic Richens]

I've noticed that the automatic transmission on this Subie does not go
into torque converter lockup when the car is cold.

How can you tell?

 

[Edward Hayes]

It will not lock-up until a reselected transmission tempter is reached. I
protect the engine from lugging when cold. eddie. My 2000 Forester takes ~
5+ minutes in cool temperatures. eddie

 

[Carl 1 Lucky Texan]

ED, what would be bad about lugging an engine when cold? Is it an oil
circulation thing? Generally, an engine will heat up more if lugged due
to longer duration of exhast gasses in cylinder/head area.

tia

Carl
1 Lucky Texan

 

[Orienteer]

The lock-up doesn't work until the oil temperature reaches about 18-20C. I
guess it is to protect the transmission, by warming the oil up to its
working temperature as soon as possible; the torque converter slip will heat
the oil.

 

[Mike]

I can tell by 1) watching the tachometer and 2)listening to and
feeling the engine change pitch.

Mike

 

[Edward Hayes]

Carl 1; Lugging an engine is asking for high loads at very low rpms which
raises combustion pressures very high which is tough on slow turning
bearings. Hydrodynamic lubrication requires some minimum shaft speed to
achieve best lubrication. In addition; cylinder walls & pistons are
lubricated by oil thrown from the spring crankshaft and cold oil is thick.
Porsche did an extensive study years ago and determined that oil has a
preferred running temperature( where it lubricates) the best and it was
quite high as I remember, something like 170 degrees F.

 

[R]

ED, what would be bad about lugging an engine when cold? Is it an oil
circulation thing? Generally, an engine will heat up more if lugged due
to longer duration of exhast gasses in cylinder/head area.

I think it protects the torque converter clutch from slippage when the
fluid is too thick to allow it to lock up properly.

 

[Edward Hayes]

Maybe it serves a dual purpose R???? eddie