Shuddering/Rumbling at Low RPM + Noise - GMC Acadia Forum: AcadiaForum.net
 
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post #1 of 10 (permalink) Old 04-18-2019, 11:05 PM Thread Starter
KMO
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Shuddering/Rumbling at Low RPM + Noise

I have a 2012 Acadia with a new problem. I'm getting a short (2-3 seconds) shuddering/rumbling sensation under slight load, and at about 1,500 RPM's, plus or minus. The shuddering/rumbling sensation can easily be confused with running over a rough spot on the road, so it isn't severe. The rumbling sensation is often accompanied by a metallic scraping/vibration sound from beneath the car (not from engine area). The car has 88,000 miles on it, and since one GM mechanic suggested this was likely a misfire issue, we replaced the spark plugs. The problem persists. No computer codes have been sent. Three different GM shops have scratched their heads over this, but none has a definitive answer for it. Today I was advised to use some injector cleaner, and arrange for a transmission flush & fluid replacement. It seems like we're just guessing and playing process of elimination (with my money). Anyone?
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post #2 of 10 (permalink) Old 04-19-2019, 12:14 AM
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Good luck.
If its a certain rpm, my guess is that its not engine related, but transmission related. Mine started that way, then at other rpms based on gear shifts. Much worse uphill than downhill acceleration. In the space of 3 days it went from noticeable to undriveable. No codes were thrown until the car couldn't move and the tcm disengaged the transmission. All this happened when I was at the highest elevation road in the Angeles Forest, truly the middle of nowhere when it comes to SoCal.
2 weeks later, I get my car back from dealer a couple days ago. Drives like new.
$5,526 transmission replacement with 100,000mi unlimited time warranty.
My odometer was at 100,700 when it happened. Didn't faze me, expected it when I first bought the car new (2015 Denali awd). Wouldn't have bought it if I couldn't get the max extended warranty at dealer cost ($3,750 for 150,000mi 6 yrs)
Triple drain/refill at 49k mi and 97k mi, didn't make any difference. 1-3-5-R waveplate, some solenoid, chunks of metal in the fluid. Oh, I had added a temp-controlled fan equipped high performance transmission cooler when I first bought the car. Fluid was always kept on the cool side. Didn't help either. Master tech said I did everything right. My interpretation of that was that nothing can be done to prevent premature failure of a poorly designed transmission. It is what it is.
Now that the GX460 is avail with captains chairs (2017+), I know what will be next for me.

Last edited by psychoknightx; 04-19-2019 at 12:19 AM.
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post #3 of 10 (permalink) Old 04-19-2019, 08:50 AM Thread Starter
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Master tech said I did everything right. My interpretation of that was that nothing can be done to prevent premature failure of a poorly designed transmission. It is what it is.
Thanks, psychoknightx, for your reply. I have read similar posts to mine here on this forum, reporting a shuddering problem. Sometimes it was the transmission, like yours, but other times money was spent on a variety of fixes, including the transmission, only to have the problem persist. I've been to three GM shops, and two independent shops thus far. Only two of the five have "suggested" the transmission could be the problem, but they are far from definite. Replacing the tranny is a pretty expensive fix. If the shuddering problem remained after doing so, I'd be sick...
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post #4 of 10 (permalink) Old 04-20-2019, 05:56 AM Thread Starter
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Well, even though I am sure there is a technical solution to the problem I described here, I came to a practical solution that works for us. We decided to trade in our 2012 Acadia to our local dealership yesterday. Their service department was fully aware of the issue we were dealing with, so no one was deceived about it. They will figure it out. So, what did we trade it in to purchase? A 2017 Acadia! My wife was the primary driver of our 2012 model, and she loved the car for six years. She was thrilled to start fresh with a 2017 model. So, I have no technical solution to share regarding the issues we were having with the 2012 model, but we are pleased to start fresh. The service manager will advise me of the status of our trade-in for as long as they have it. If I learn of any specifics, I shall share them here. Otherwise, we're off and rolling...
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post #5 of 10 (permalink) Old 04-25-2019, 07:16 PM
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I replaced my 2012's transmission at 103k mi for a similar issue.

2012 Acadia SLE2 w/ AWD, tow, added homelink, added DIC switch
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post #6 of 10 (permalink) Old 05-02-2019, 09:08 PM
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I have the same issue on our 2008, trans flush helped for a bit, then same when I repeated it but likely the torque converter is just not engaging fully anymore
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post #7 of 10 (permalink) Old 05-03-2019, 08:02 PM
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At about the same mileage, my 2014 Denali had a similar shudder at 25 or 30 mph when on a mild grade up. After hitting 35 or 40 it smoothed out. Dealer tested by replacing one bank of plugs/test drive, then the other. No change. Replaced torque converter with a rebuilt one, that did it. No problems after another 25k miles.
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post #8 of 10 (permalink) Old 05-04-2019, 04:49 AM Thread Starter
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At about the same mileage, my 2014 Denali had a similar shudder at 25 or 30 mph when on a mild grade up. After hitting 35 or 40 it smoothed out. Dealer tested by replacing one bank of plugs/test drive, then the other. No change. Replaced torque converter with a rebuilt one, that did it. No problems after another 25k miles.
That sounds extremely similar to our problem, and replacing the plugs was our first move as well. We decided to cut our losses and quit guessing before continuing down the "try this" sequence of expenses. After continuing to discuss the problem with a local GM mechanic, the torque converter could very well have been the problem with our 2012 Acadia too. Glad you resolved yours billg.
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post #9 of 10 (permalink) Old 05-14-2019, 02:45 PM
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Did you have any CEL codes or just a shudder? I've had one shop suggest the waveplate but from my research that just causes an abrupt loss of the 3,5,R gears and not a shudder.
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post #10 of 10 (permalink) Old 05-14-2019, 06:24 PM Thread Starter
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Did you have any CEL codes or just a shudder? I've had one shop suggest the waveplate but from my research that just causes an abrupt loss of the 3,5,R gears and not a shudder.
No codes sent on this one. I was left thinking the problem was likely the torque converter, but I decided to trade in my 2012 Acadia for a 2017 Acadia. My wife drives the car the most. She loved her 2012 model, and now she loves her 2017 model even more...
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