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Discussion Starter · #1 ·
For the past two days, when driving at any speed, the transmission doesn't seem to shift when picking up speed. It drives ok, the transmission is full of clean fluid (looked at dipstick cold and hot), nothing else seems to be going on. There aren't any error lights or codes that pop up.

Its just when I pick up speed, I don't notice any shifting going on, it just hums louder and vibrates a bit more......like driving over a rough surface.

Nothing is leaking, nothing is "wet" under the hood. There isn't any smoke or burning odors. I don't see any frayed wires, or broken hoses.

This is the first vehicle I've ever had with a computer in it, so I'm unsure of if this is usual with high mileage on these types of vehicles or what.

I bought this in 2017, and the GM dealership did a clean and fill on the transmission fluid when I got it.

Any thoughts?


2012 Acadia, V6, automatic
110,000 miles
Nothing fancy, just a basic model.
 

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Discussion Starter · #4 ·
A qualified transmission tech with the proper scan tool can probably diagnose the problem for you.
Yeah, I'm going to do that. But just wondered if maybe it's just an age thing or maybe just something that happens with high mileage trannies.

I drove it again yesterday, and I felt it shifting when it should, so I can only guess that some part has worn down. Geez, more bills I can't afford. UGH:cautious:
 

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I drove it again yesterday, and I felt it shifting when it should, so I can only guess that some part has worn down. Geez, more bills I can't afford. UGH:cautious:
Could be the TEHCM laminate disks are worn/damaged. Cost to replace them is fairly minimal when compared to other procedures.
 

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Please check your transmission fluid level per the proper procedure to verify it is at the correct level.

A transmission that has too much fluid will create cavitation and air bubbles. This changes the contact/surface properties of the components resulting in torque shudder and lags in shifting upon acceleration. A band-aid solution is adding a surfactant such as Lubguard Shudder Fix. This temporarily solves the problem by changing the fluid properties to reduce cavitation and air bubbles.

Unfortunately, many people have spend several thousand dollars on replacing the torque converter or the entire transmission due to the transmission being not filled to the correct level.
 
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