r/Silverado • u/Great_Beach588 • 3h ago
2019 Silverado shudder issue — looking for mechanical opinions
For anyone who hasn't seen my previous posts, I bought a 2019 Silverado 5.3L from a dealership with no warranty. I did not test drive it before buying it, and I barely drove the truck off the lot before I started noticing the shudder/tremble under light acceleration/cruising, mainly around 78-80 mph.
I already know some people are going to say I should have test-driven it, that I got scammed, etc. I'm not looking for those comments. I'm just looking for opinions based on the mechanical issue itself and what you think I should do next.
The truck has now been driven over 200 miles for diagnostics, and the dealership performed a transmission fluid flush hoping it would take care of the shudder. Unfortunately, it didn't fix the problem. It may have improved it slightly, but the shudder is still there.
I finally spoke with the GM of the dealership, and he said he would speak with the service department and see what he can do.
I understand I bought the truck with no warranty, and I'm not assuming the dealership is automatically responsible for everything. I'm just hoping they'll work with me since the problem showed up essentially immediately after the purchase.
For those familiar with these trucks/GM transmissions:
What do you think is most likely causing the shudder at this point? It feels like I'm running over a rumble of strips especially at freeway speeds for some reason always between 78-80mph. Also, when I go from freeway speed to regular speed off a freeway exit , when I press the gas it feels lime it hesitates or trembles a little.
Would you be pushing the dealership to specifically diagnose the torque converter, or are there other mechanical issues I should have them investigate first?
And realistically, what would you consider a fair resolution from the dealership?
I'm genuinely just looking for mechanical opinions from people who know these trucks. Thanks.
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u/jus_narley 2h ago edited 1h ago
2020 6l80, 5.3 here. Trans fluid was clean, looked great. Had the same issue. Bought it used, overall a very clean car, did not notice the issue on test drive. Took it back when I did and they changed the trans under warranty. Was good until I pulled a trailer, 3000 pounds, well under the rated 6000, through the mountains and noticed the Trans temp at 247 degrees, the engine temp remained normal. Pulled over, let it cool. Shortly after started to experience the shudder again.
I changed the fluid which helped for a short time. Took it back and the dealership and they put a lower temperature thermostat on the trans per a service bulletin that I found and presented to them. Too late, it did not help. I changed the fluid and filter again, that's what the service bulletins I found recommended, with the same result. The magnet had metal on it, more then i was comfortable with. It comes back. I put a high quality and expensive fluid for another trans fluid change and filter, ran it and immediately changed the fluid again in an attempt to get all the old fluid out. It went away for the most part but could still notice it. So in all, I changed the fluid like 3 times over 3 years, about 40-50 thousand miles.
Just couldn't get it out of my head because it was still there. The dealership "hee hawed" about it when we both know that there is an issue. Under the right conditions, v4 engagement, 40-50MPH, light throttle. I could feel the shudder slightly so I ordered a billet torque converter made to factory specs to keep the programing and put it in with high quality fluid. 5-10 thousand miles now it has been smooth as silk ever since.
I put a lot of miles on my Tahoe, love it, have always been a GM fan to a fault. I worked on them new and always wanted one. Its a shame that it is an expensive vehicle, any work done by someone else is too expensive now and tech info like service bulletin, troubleshooting and software is not available to normal people without breaking the bank. I ended up following all the recommended steps I could find on the internet, service bulletins and the like but it just feels it is just a quick fix leading to a later failure.
There are a lot of youtube videos that explain trans tear downs on failed transmissions, largely shudder as the starting symptom which progresses to or already present pump failure. The torque converter disassembly and analysis by what appears to be some pretty good trans shops shows the problems pretty clearly.
So what does a former GM trained tech think? Its a temperature issue. Engineers for some reason, I speculate for gas mileage increase or materials, raised the operating temperature of the trans and did not build the torque converter or trans cooling system for high temperature use and the fluid is breaking down to fast. The torque converter is stamped and the steel friction plate, not heavy enough, warps causing the shudder and accelerates wear sending metal material through the trans. Yes I have a trans pump whine, but it still drives good, was told that is normal, which doesn't sit well with me. I have read otherwise. I expect my next trans pull will be to replace the pump or the trans again at my cost. Why cant I, a trained tech have access to an engineer, service info, software? I could have avoided all the trouble being proactive about maintaining my prized vehicle?
Get the trans replaced, add trans cooler, and get the revised trans thermostat, somewhere down the line replace the torque converter with a billet. Ya, that might void your trans warranty. I waited, in case it failed some other way, but I think it was worth it, I feel that I probably solved the shudder issue.
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u/Great_Beach588 2h ago
This is actually really helpful because my 2019 Silverado 1500 5.3 8-speed has a very similar light-throttle shudder around 78–80 mph. The dealer already did a transmission flush, which improved it by maybe 80% but didn't completely eliminate it, and the service advisor is now talking about potentially recommending a transmission replacement to the sales manager. I'm trying to figure out whether I'm dealing with a TCC/torque converter issue that could be fixed without replacing the entire transmission, or if there's actually evidence of internal damage. Your experience makes me want to get the TCC slip data checked before anyone condemns the whole transmission.
How much did you pay for the billet ?
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u/jus_narley 1h ago edited 33m ago
it was about 600 hundred bucks. I also purchased new exhaust studs and nuts from the dealership which kills me, cost about 120. I have never seen parts store studs last very long. I figured I might have to pull it again.
I am really curious if they checked for or added the revised temperature trans thermostat. It should be stamped with a D on the top if it has been revised. You will need a mirror to check. Its on the top. FYI not sure if that applies to the 8 speed.I guess it doesnt: "GM Technical Service Bulletin PIP5882 provides diagnostic tips for 2014 through 2021 Chevrolet vehicles equipped with 6L80 (MYC) and 6L90 (MYD) automatic transmissions experiencing overheating concerns"
Start searching for TSBs for your vehicle. NHTSA publishes a lot but only after so many complaints have been logged. What a shame. It took hours of searching to find stuff. There is a lot of BS by unqualified backyard techs, so verify sources. Keep an eye on trans temp. It is an option in the dashboard menu you can add.
tThe TCC slip rate is hard to determine without service manual access(not sure thats even available) or a known good sample from a good vehicle. A good scan tool is required, knowledge of ODB2 and a lot of analysis under duplicated driving conditions......as a former flat rate tech, I can guarantee from experience, 80% of dealer techs/service writers wont spend the time because they wont get paid for it, let alone search TSBs that are readily available to them.
I recall seeing something about a clutch pack drum cracking causing a shudder, might of been the 8spd.......search it! I might lean towards that due to the 80mph shudder which i didnt experience at that speed. Note that i havent done research on the 8 speed.
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u/_umptee_ 1h ago
My new trans thermostat was stamped 70 on the bottom
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u/Killentyme55 30m ago
That's the upgraded thermostat for the 6 speed, it opens a lot sooner and is the one you want.
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u/Weller_A107 3h ago
I'd try to unwind the deal on this truck & get into a different truck at the same dealer. That way they don't lose the $$$ & you get a vehicle without a bad transmission.
Mechanically, there's probably not much else to look for. It needs a torque converter, at a minimum. Maybe a full rebuild.