Transmission not engaging when it gets hot?

2006 TOYOTA COROLLA
150,000 MILES • 1.8L • 4 CYL • 4WD • AUTOMATIC
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MARCMATROY123
  • MEMBER
  • 1 POST
After a transmission overhaul we changed the oil pump, clutches, and some seals. We also rebuilt the primary variator, just the seal, we wrapped some cotton on the base where the seal sits as the air pressure test failed after rebuilding. The vehicle runs perfectly when cold but once the transmission gets hot no gear is engaging.
May 31, 2023 at 1:26 PM
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JACOBANDNICKOLAS
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 110,190 POSTS
If you lose all gears, it sounds like you are losing line pressure. Have you been able to check that? Also, have you checked to make sure there aren't relevant diagnostic trouble codes related to the transmission?

I attached the directions below for testing line pressure. Let me know if this is something you are comfortable performing.

Take care,

joe

See pics below.
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Jun 1, 2023 at 10:15 PM
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STRAILER
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 54,182 POSTS
Are there any codes?

Here is a guide to help us:

https://www.2carpros.com/articles/why-does-your-automotive-transmission-not-engage-when-it-gets-hot-a

Also, it sounds like you may have a bad fluid pressure switch which I have included the location in case a code comes up for it.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.
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Jun 2, 2023 at 7:12 AM