2020 Sierra Transmission cooler leak.

Pyroman_28 · March 5, 2020

So I was merging on the highway the morning when I got a strong odor of transmission fluid in the cab. Within 2 minutes the transmission started to slip pretty extensively above 1/4 throttle so I limped it to the next exit only to find that theres a fairly massive leak where the trans line connects to the cooler. Currently waiting on a tow truck but has anyone else had any issues like this or is my bad luck streak as strong as ever? Truck is about 3 weeks old and has a little over 2k miles of grandpa driving for the most part.

bucket772 · March 18, 2020

yep. Almost the same circumstances. Noticed all the smoke out of the back. Had it towed and it was the same issue.

spizike9 · March 18, 2020

Bummer guys. That has to be frustrating.

bucket772 · March 18, 2020

now its back in for a clunking noise that I noticed more backing and turning and when the suspension loads. Sounds like a car with bad sway bar bushings. Doubt they are worn out with less then 2200 miles. Also noticed a chirping sound coming from the front. sounds a lot like the differential issues the 2019's had. Its been there since Friday.

redvettez06 · March 19, 2020

Oof. Which engine and tranny does your truck have?

Pyroman_28 · March 19, 2020

10 hours ago, redvettez06 said:

Oof. Which engine and tranny does your truck have?

Ive got the 3.0 Duramax with the 10 speed auto.

So to update my original post, it turns out the line that was leaking on the cooler had just popped off and it lost about 8 quarts. They reattatched the line, cleaned it up and topped off the fluid and it seems to be running well with the exception of this clunk downshift I now get at 57 mph. That's about the speed I was driving it at the time of the incident so I'm wondering if that particular gear was damaged.

redvettez06 · March 19, 2020

5 hours ago, Pyroman_28 said:

Ive got the 3.0 Duramax with the 10 speed auto.

So to update my original post, it turns out the line that was leaking on the cooler had just popped off and it lost about 8 quarts. They reattatched the line, cleaned it up and topped off the fluid and it seems to be running well with the exception of this clunk downshift I now get at 57 mph. That's about the speed I was driving it at the time of the incident so I'm wondering if that particular gear was damaged.

Damn that sucks. Hopefully it works it's way out eventually.