the transmission shifts hard when warm

1999 CHEVROLET EXPRESS

118,000 MILES

GSTEELE55

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After driving a while or on very hot days 90 degrees plus the transmission shifts hard. It shifts fine when it's cool. The fluid looks level looks ok. The fluid or filter has never been changed, but I was told if you do this the transmission could possibly go completely out.

Jan 26, 2013 at 3:49 PM

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SQM

CAR REPAIR CONTRIBUTOR
6,383 POSTS

Hello,

Shifting hard when it is hot can be due to contaminated transmission fluid. If the fluid is contaminated it won't be able to cool the transmission as efficiently which can lead to hard shifts. Also keep in mind that as the component of the transmission wears off this issue can worsen.

https://www.2carpros.com/articles/automatic-transmission-problems

Changing the fluid by removing the transmission pan, and replacing the filter is good maintenance. It is a good idea to do this if the fluid is dirty.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

If you still have this issue after the fluid change and being at the correct level. It is possible that the transmission will need overhauling.

Please let me know if you have any questions.
Thank you.

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Jan 6, 2022 at 9:38 PM