2021 Buick LeSabre - Thunks

It isn’t consistent, but when accelerating suddenly from from a full stop, like from a stoplight, or the on-ramp of a highway, it feels and sounds like the transmission is moving. It is a dull, thunk sound, like u-joints would make in an older car, except this sound seems to come from the place where the transmission connects to the motor, underneath the center console. Mechanics couldn’t reproduce the sound. It runs and shifts just fine, but occasionally feels like the transmission is about to drop!

Check your state’s lemon laws, and document, document as you attempt to get this problem corrected.
Take a tape recorder on your drives.

I don’t see a Buick LeSabre listed for 2021 so what year is this vehicle ?

It’s a 2005, the last year they were made

Good tip! Thanks!

I hope you don’t think that the lemon laws will apply to this 15 year old vehicle because they don’t.

Put a wrench on the engine to transmission bolts and see if they are lose. Also check the motor and transmission mounts. Check all the engine cradle bolts.


Your 2005 Buick has Front Wheel Drive, and as a result the engine connects to the transmission under the hood, adjacent to the left (?) front wheel, not underneath the center console. It is entirely possible that you have one or more bad motor mounts or transmission mounts, so I think that you need to seek yet another mechanic.

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Thanks, but no, I didn’t think they would. But it’s a good thing to know for future reference.

Didn’t know that, thanks. I will make another attempt with another mechanic.

Thanks. I’m not mechanically inclined, but I will find someone who is and ask them to check those exact things. Thanks for the tip.

Well yeah that and I’d have the CV joints checked and the flywheel bolts etc. At that age could be anything up there coming loose. Really I think a transmission shop might be more helpful in detecting a drive train noise.

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Thank you very much. I will add those connections to the list, and also try the transmission shop. Great idea!

Just be sure that you go to an independent trans shop that has been in business for at least 3 years.
Do NOT go to a chain-operated trans shop such as Lee Myles, Cottman, Mr. Transmission, or–the worst of the worst–AAMCO. They will tell you that you need a new transmission, even if only a relatively minor repair is necessary.

Thanks, I will remember that. Generally don’t trust big chains, anyway. And I’m sure the transmission is ok. Had the fluid changed when I first bought the car, thinking that might fix it!