hesitation at takeoff then hard shift

2007 BUICK TERRAZA
200,000 MILES • 2WD • AUTOMATIC
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DRAWS4
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My van has recently started this hesitation when accelerating from a stop or almost stop, say at a stop sign or slowing down for a turning vehicle in front of mine. I have taken it to a dealership, but they are not able to find any error codes or water in a connection that these are common for.

It is only sporadic, sometimes the cold makes a difference, sometimes the heat.

But the engaging or clunking when it does, is very noticeable.

Any other suggestions?
Jun 15, 2021 at 8:29 AM
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KASEKENNY
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When you are saying that this is hesitating, do you feel it is delay in transmission engagement and then it clunks into gear? Or is this more of an engine hesitation like it is short on fuel?

Here is a guide on hesitations but this may not fit your issue if it is a transmission issue:

https://www.2carpros.com/articles/engine-hesitates

If this is a transmission issue then we need to start with checking the fluid and finding out if the fluid is in good condition and full.

If not we need to start with servicing the unit.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

If the fluid is okay then this may just be the beginning stages of worn clutches so we need to keep an eye on the fluid as I suspect it will start to show signs of issues like discoloration and smelling burned.

Please run through this material and let me know if you have other questions. Thanks
Jun 16, 2021 at 3:48 PM
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DRAWS4
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I feel this is a transmission issue, delayed engagement and a clunk into gear. I have done a flush on the transmission and the dealership said the fluids all looked good.

Would worn clutches produce an error code?
Jun 16, 2021 at 6:46 PM
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KASEKENNY
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Eventually it will but we need to do a little more research before we get there.

Does this do this often or is it more random?

If this does not happen frequently then that is good but makes it hard to figure out.

Do you think it is possible to get a video of it doing it? Clearly the issue is more of a feeling but I am hoping we will see something with the RPM that would narrow in on a valve body issue or a worn clutch issue.

Basically the clutches are what is causing the feeling as they are what actually engage the gear but if we have a valvebody/solenoid issue then the clutches will be fine if that is fixed.
Jun 17, 2021 at 8:39 PM
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DRAWS4
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I can try for a video but it is currently in the shop. Are the valve body/solenoid issue something that can be changed without tearing the transmission apart?
Jun 18, 2021 at 8:00 AM
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KASEKENNY
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You do have to remove the side pan but you do not have to remove the interior portions of the unit.

I attached the entire process for your review.
Jun 19, 2021 at 7:10 PM
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DRAWS4
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The shop has finally come back with it being a solenoid, and wants $1,400.00 + tax to fix it. My husband is mechanically inclined, but is this a big project to undertake? Or should we just pay to have the "professionals" do it? I tried to do the video, but it just didn't work well.
Jun 23, 2021 at 4:05 PM
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KASEKENNY
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This is a pretty big job. You have to remove the pan, remove the valve body and then remove the faulty solenoid. I attached the valve body process above and will post the solenoid process below depending on which solenoid is the issue.

$1,400.00 does sound high so I suspect they are replacing all of them or the entire valve body. Do you have a copy of the estimate that they provided? Can you get a picture of their right up where they diagnosed it?

Please see the info below and let us know if you have questions. Thanks
Jun 24, 2021 at 6:58 PM