10L80 transmission lines leaking

[Patrick Callery]

I have a 2021 Silverado 3.0. 
changed the oil yesterday and found wet transmissions lines at the rubber line fittings that are pressed on. At least 4 of them at the back of the engine above the oil pan drain. 
    I’ve got 111,000 km or 70,000miles. Warranty is over but I bought an extended warranty. Not sure if it will cover it. I don't  want to waste $120 for the dealer to look at it and tell me it’s not covered. 
    Anyone have this issue ? Anyone change the lines themselves. 
   I’ve owned GM vehicles all my life and have never had a trans line leak.  

[newdude]

1 hour ago, Patrick Callery said:

I have a 2021 Silverado 3.0. 
changed the oil yesterday and found wet transmissions lines at the rubber line fittings that are pressed on. At least 4 of them at the back of the engine above the oil pan drain. 
    I’ve got 111,000 km or 70,000miles. Warranty is over but I bought an extended warranty. Not sure if it will cover it. I don't  want to waste $120 for the dealer to look at it and tell me it’s not covered. 
    Anyone have this issue ? Anyone change the lines themselves. 
   I’ve owned GM vehicles all my life and have never had a trans line leak.  

 

 

 

 

Check your extended warranty paperwork and see if they are covered.  Or if its not listed in there, call the warranty company and see if they are covered.  

[Bikerjon]

On 3/31/2025 at 9:59 AM, Patrick Callery said:

I have a 2021 Silverado 3.0. 
changed the oil yesterday and found wet transmissions lines at the rubber line fittings that are pressed on. At least 4 of them at the back of the engine above the oil pan drain. 
    I’ve got 111,000 km or 70,000miles. Warranty is over but I bought an extended warranty. Not sure if it will cover it. I don't  want to waste $120 for the dealer to look at it and tell me it’s not covered. 
    Anyone have this issue ? Anyone change the lines themselves. 
   I’ve owned GM vehicles all my life and have never had a trans line leak.  

Common problem. Lots of postings on here about leaking trans. cooler lines. Get it fixed ASAP.

[Patrick Callery]

Thank you for your advice. I’ll replace the line harness with GM parts. My understanding is it will happen again. Some guys are cutting the aluminum lines and flaring the ends. Then adding replacement lines and 2 hose clamps on the line behind the flare to stop separating. I’d like a long term fix with better part. 
 It’s frustrating everyone has leaks after 100,000km or 65,000miles. 

 

On 3/31/2025 at 12:34 PM, newdude said:

 

 

Check your extended warranty paperwork and see if they are covered.  Or if its not listed in there, call the warranty company and see if they are covered.