Balls in my transmission?! 2021 GMC Sierra 1500 AT4 3.0.

diyer2 · July 28, 2023

Trade it in on a Toyota?

BIGDOGx · July 28, 2023

Sorry to hear it let go, i would talk with your dealers service department to see if anything can be done, perhaps they could get gm to cover a portion, i believe you said they flushed it originally and imo that flush is more then likely what started this damage.

I think you need to assess more then just should i ditch it, higher interest rates, banks refusing loans right now all factors in trading out. You will be basically throwing any equity you had with this truck out the window and starting over with nothing.

And there is nothing made today, that is guaranteed to drive 300,000 miles. Sure you could get a truck to drive that amount, but it will come with at least 1 trans overhaul and no doubt many other issues along the way. If i say show me a trouble free vehicle that could last that long without major repair, all you will show me is the most simplistic of designs from around half century ago. These things today are far too complicated to not break and need maintenance, simply what you seek no longer exist or is made.

josh mcquown · July 29, 2023

Thank you all for the comments / feedback. Here’s a quick update. I spoke to a GM Corporate customer service rep. GM has what they call a “just out of warranty” program, which covers 6000 miles or 200 days over the warranty. GM is covering 70% of the transmission repair. Working with GM customer service directly has been a blessing. The customer service rep also mentioned, if I ever want GM to review a repair bill, just send them a copy and they will do their due diligence.

I’ll post an update with the total cost and what was done when I pick the truck up. It should be about 10 days. I hope to get some feedback as to what failed in the transmission, but I doubt the dealership will open the tranny.

seamus2154 · July 29, 2023

With current interest rates and the new trucks about 13K more than the old truck just a few yrs old its cheaper to fix IMHO. The new prices are out of control. 7500 or 75K for a new truck. You have no present equity going towards a new truck at 7% interest on top of it. The LM2 has been super reliable and looks like it will be be a high mileaage motor by all accounts. I would do the oil drive belt while the trans is out, and a new GM trans all day if it were me. I would be very vocal about how much the cooler and trans lines NEED to be flushed properly not to contaminate your new trans.

Spurshot · July 29, 2023

26 minutes ago, seamus2154 said:

With current interest rates and the new trucks about 13K more than the old truck just a few yrs old its cheaper to fix IMHO. The new prices are out of control. 7500 or 75K for a new truck. You have no present equity going towards a new truck at 7% interest on top of it. The LM2 has been super reliable and looks like it will be be a high mileaage motor by all accounts. I would do the oil drive belt while the trans is out, and a new GM trans all day if it were me. I would be very vocal about how much the cooler and trans lines NEED to be flushed properly not to contaminate your new trans.

I think I'd just tell them to change the cooler/(AC condensor?), flush the lines and you'll pay for the new cooler.

seamus2154 · July 29, 2023

The trans cooler. Notorious for holding crap and screwing the new trans upon new fluid going through the lines. True PPE upgraded cooler is about 330 bucks, a good time to upgrade and also their thermostat. The 10 speed has been doing pretty good, 100K for a trans is not normal. Things happen but with GM helping out on this its a no brainer to fix. But the flush before new trans is a must.

Bikerjon · July 29, 2023

Great! Very happy for you. This should renew your faith in GM.

TxTruckMan · July 30, 2023

And FYI the GM and Ford 10 speed trans are the same design I believe. Designed by Ford.

Andrew01 · December 1, 2023

Hi ,98500 miles and my 3.0 duramax just today has a bad vibrating noise in the transmission . Still shifting and not over heating. Any ideas?

Bikerjon · December 1, 2023

1 hour ago, Andrew01 said:

Hi ,98500 miles and my 3.0 duramax just today has a bad vibrating noise in the transmission . Still shifting and not over heating. Any ideas?

Welcome to the forum. I would take it into a dealer and have it tested/inspected. Be specific with the Service Writer and give them a detailed description of the problem. I would ask for a road test with a Trans. Mechanic. You could pull the dip stick on the transmission to see if the fluid is burnt smelling and wipe it on a clean cloth, if it is burnt looking or black in color that usually indicates worn clutch packs. (Overhaul or replacement needed).

Keep us informed about your situation. Good luck.

SVG · December 1, 2023

16 hours ago, Andrew01 said:

Hi ,98500 miles and my 3.0 duramax just today has a bad vibrating noise in the transmission . Still shifting and not over heating. Any ideas?

I'd get it into the dealer ASAP. You'll stand a good chance of eating all or some of any repair costs if you're beyond 100K miles.

redwngr · December 1, 2023

14 hours ago, Bikerjon said:

Welcome to the forum. I would take it into a dealer and have it tested/inspected. Be specific with the Service Writer and give them a detailed description of the problem. I would ask for a road test with a Trans. Mechanic. You could pull the dip stick on the transmission to see if the fluid is burnt smelling and wipe it on a clean cloth, if it is burnt looking or black in color that usually indicates worn clutch packs. (Overhaul or replacement needed).

Keep us informed about your situation. Good luck.

Does your truck have a transmission dipstick?

Bikerjon · December 2, 2023

9 hours ago, redwngr said:

Does your truck have a transmission dipstick?

No it does not. Must have been thinking about the olden days. My mistake.

Andrew01 · December 2, 2023

Thank you , I’ve called all my local dealers who are weeks out to even look at it and months out from fixing it. They say “O it’s diesel, our diesel tech is busy” I said but it’s a transmission not an engine. Anyway Waiting that long isn't an option so a local transmission shop will look at if next week hopefully . Thanks guys.

Andrew01 · January 9

Hello , I eventually got a dealer to take it and I still had warranty. Turns out it was the oil pump went bad. Is this common? Anyway I also had the wet belt changed since the transmission was out.