Automatic transmissions have thermostats and others don't?

Tiny
YOUSEEKYOTA
  • 2004 TOYOTA CELICA
  • 123,000 MILES

Why do only some automatic transmissions have thermostats and others don't, and what exactly is their purpose exactly? I was talking to a Mechanic from Toyota and he informed me My auto transmission has a thermostat the regulates when it will Allow my car shift gears

He also said not all cars have this

Why not and why regulate when to shift by temperature?

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Wednesday, May 23rd, 2012 AT 8:49 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
  • 26,026 POSTS

Not a thermostat, but a temperature sensor. Most cars use the engine's coolant temperature sensor. The transmission will always shift through first, second, and third gears when cold but it may not go into overdrive until the engine warms up. To do so puts more load on the engine and since it's turning slower, it pumps less oil and since the transmission oil is cold it's relatively thick, so it won't circulate as freely to important places. Some transmissions have a temperature-controlled valve to stop transmission fluid from circulating through the cooling tank inside the radiator until it warms up. That helps the fluid get warmed up faster, then the transmission will be allowed to shift into overdrive.

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Wednesday, May 23rd, 2012 AT 9:07 PM
Tiny
YOUSEEKYOTA
  • MEMBER

That makes so much sense. Thank you for your quick reply it was a huge help

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Wednesday, May 23rd, 2012 AT 10:10 PM
Tiny
SATURNTECH9
  • EXPERT
  • 30,274 POSTS

Just to add this one toyota does that for emissions reasons so the engine warms up quicker. Its there way to meet emissions and keep the epa happy.

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Thursday, May 24th, 2012 AT 5:07 AM

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