Coolant mixing with transmission fluid?

DERRICK GIANAKIS

MEMBER
2007 CADILLAC CTS
3.8L
V6
2WD
AUTOMATIC
144,000 MILES

After car is warmed up, getting it to shift when driving 30 mph is maxing my rpm's. My line from transmission to radiator got pulled out and I noticed the color of the fluid coming out was a coffee with creamer color. I replaced radiator and transmission fluid and filter, filled radiator with water for temporary. Still have same colored fluid in my coolant reservoir and that's when I can't shift out of first or maybe second anymore. I wasn't having a problem I don't think before that line got ripped out. But I replaced it and the fluid and new radiator and can't figure this out. Don't want to pay the dealership. Please help.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

Hello,

Here is a guide to help you do the cooling system and transmissions service. Make sure you replace the radiator as well the cooler is bad inside.

https://www.2carpros.com/articles/how-to-replace-a-car-radiator

and

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

and

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

Yep, the transmission does not like coolant inside. but lets run the codes to see if you have a shift solenoid that is not working correctly. Here is a guide to help us:

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

Please run down these guides and report back.

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Tuesday, September 24th, 2019 AT 1:06 PM

GERALE2010

MEMBER
2 POSTS
2003 CADILLAC CTS

Radiator went out, transmission fluid mix up with antifreeze got inside both transmission and coolant, what should I do to flush it all out

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Wednesday, March 31st, 2021 AT 9:50 AM (Merged)

FACTORYJACK

MECHANIC
4,159 POSTS

You can flush them out the best as possible, as soon as possible. You may still have transmission issues, as the coolant de-laminates the clutches. Also, you may notice the rubber components of the cooling system sweating oil as it attacks and softens the rubber. Here is a guide to help you do the cooling system and transmissions service. Make sure you replace the radiator as well the cooler is bad inside.

https://www.2carpros.com/articles/how-to-replace-a-car-radiator

and

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

and

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

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Cheers

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Wednesday, March 31st, 2021 AT 9:50 AM (Merged)