Major vibration when accelerating

Tiny
ZACKARY MERCER
  • MEMBER
  • 2005 PONTIAC GRAND PRIX
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 240,000 MILES
I get a major vibration when accelerating between 45-65 mph. But nothing at any other speed. I’ve had the tires balanced twice and the vibration does not come through the steering wheel but instead it’s just the entire car shaking.
Friday, April 12th, 2019 AT 11:44 AM

8 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

Does it feel like the entire car, front end, or engine related?

Could be a motor mount, Torque converter in the transmission or possibly a harmonic balancer.

Roy
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Friday, April 12th, 2019 AT 12:34 PM
Tiny
ZACKARY MERCER
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  • 5 POSTS
Thank you.
The engine mounts look good and it feels like the front end is vibrating. It doesn’t feel engine related though, but when accelerating at the particular speeds the shaking can get bad enough to where the sound the engine creates fluctuate.
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Friday, April 12th, 2019 AT 1:35 PM
Tiny
ASEMASTER6371
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Did you have someone check the front suspension for you to see if there are any worn parts?

Roy
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Friday, April 12th, 2019 AT 1:41 PM
Tiny
ZACKARY MERCER
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Not yet, I do know the strut assembly is needing replacing though. And the last time I had an alignment done was almost a year ago and nothing was wrong with the front end at that time.
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Friday, April 12th, 2019 AT 2:40 PM
Tiny
ZACKARY MERCER
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Update: I drove it around a little bit but I decided to open up the hood and give the car a push while in park and it caused the engine to move a good amount. Maybe the engine mounts might be bad?
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Friday, April 12th, 2019 AT 3:20 PM
Tiny
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Yep, that sounds about right. I attached a guide for you for replacing the mounts.

https://www.2carpros.com/articles/replace-motor-mounts

Roy

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Friday, April 12th, 2019 AT 3:26 PM
Tiny
ZACKARY MERCER
  • MEMBER
  • 5 POSTS
I went ahead and replaced them. But I don’t think it helped with the vibration. But at least I won’t ever have to replace them again because it probably still needed it. I went ahead and checked transmission fluid and it was at a good level but very dirty.
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Saturday, April 13th, 2019 AT 4:18 PM
Tiny
ASEMASTER6371
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Are these the mounts you changed? The upper mounts have a left and right.

Roy
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Saturday, April 13th, 2019 AT 4:25 PM

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