Transmission not pulling?

SPJORDAN2

MEMBER
2008 CADILLAC CTS
3.6L
6 CYL
2WD
AUTOMATIC
125,000 MILES

After finding that the transmission cooler was leaking into radiator and fluids had mixed, I replaced radiator, drained trans fluid and replaced fluid and filer flushing as best as I could. Put all back together and the transmission will not pull in D. Exactly what it was doing before I found the cooler problem. It will go through all gears in Sport Mode "M", but when put in "D", will start to pull, but when I press accelerator pedal, transmission stops pulling. Engine just revs up. Any ideas?

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,753 POSTS

Hi,

Engine coolant can cause different things to fail in the transmission. How much of the fluid were you able to remove when you did the service? Keep in mind, the torque converter would have been full of fluid and unless you flushed it, that fluid is back in the transmission.

If you changed all fluid, the next thing we need to check is line pressure. Damage to the torque converter or front pump may have occurred. I'm basing that on the idea that it doesn't slip when you shift manually.

I attached the directions below for checking line pressure. You will need a pressure gauge and scan tool that can communicate with the vehicle. Take a look through the directions and let me know if you feel comfortable performing this.

Additionally, recheck the transmission fluid and see if there appears to be any contamination.

Let me know.

Joe

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Saturday, July 1st, 2023 AT 8:24 PM

SPJORDAN2

MEMBER
2 POSTS

I couldn't be sure how long the fluids were mixing before I discovered the radiator issue. I do know that the first sign of an issue was the transmission not pulling in "D". I drained all I could from the pan and then ran the car and let it pump out through the line to the radiator cooler. I added several quarts and let it continue to pump out. I did not get an official "flush" done. I do not have the pressure tester and the only scan tool I have is the $40 one from Walmart. The fluid does seem to still have a pinkish color. Also, when I do run it now in "M", there is a "hot" smell coming from the car. Like clutches burnt. I am looking for if it is worth trying to determine if it could be like a solenoid or something that needs replaced or should I just be looking for a used or rebuilt transmission.

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Sunday, July 2nd, 2023 AT 10:33 AM

JACOBANDNICKOLAS

MECHANIC
109,753 POSTS

Hi,

If you are smelling clutches burning, it could be a pressure issue, but I have a distinct feeling it needs to be replaced.

I guess you could remove the pan again to see if there is evidence of clutch material and then decide if you want to do further testing. The idea that it doesn't move in drive is the thing that makes me believe it needs to be replaced. When you drive in M, is there any slippage? I would suspect there is simply because of the smell.

Let me know. Also, let me know if there is anything I can do to help.

Take care,

Joe

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Sunday, July 2nd, 2023 AT 2:02 PM