Thumping in front end when accelerating

Tiny
SHANANAGANS75
  • MEMBER
  • 2004 PONTIAC GRAND PRIX
  • 3.8L
  • 6 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 211,444 MILES
For the last 2 weeks when I accelerate there's a loud thumping sound coming from my front end. It gets faster and louder as I accelerate and does not seem to do it when at a stop. Today I replaced my sway bar links I was told by a neighborhood mechanic that's what it could be and it wasn't. Any suggestions to what it may be?
Sunday, September 6th, 2020 AT 6:57 PM

6 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This sounds like a rotation noise which would be a bearing, wheel, or tire issue. Can you get a recording of it?

Also, I would suggest lifting the tire that it sounds like it is coming from and just spin the wheel by hand to see if you can hear it. If not we need to inspect the tires for wear.

https://www.2carpros.com/articles/how-car-tires-work

Try this and report back what you find. Thanks
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Sunday, September 6th, 2020 AT 7:05 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Does the sound seem to match how fast the tires are turning? Have you checked the condition of the tires for flat spots, belt separation, and so on?

If you did check tire condition, check to make sure there isn't a bad motor mount and nothing is loose as far as the CV joints are concerned. Also, if it is possible record the sound and upload it so I can hear it. Plus, let me know if you feel it in the steering wheel or more in the floor and seat of the vehicle.

Take a look through this link and see if anything mirrors what you experience.

https://www.2carpros.com/articles/symptoms-of-a-bad-cv-axle-joint

Let me know.

Joe
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Sunday, September 6th, 2020 AT 7:08 PM
Tiny
SHANANAGANS75
  • MEMBER
  • 3 POSTS
We have checked anything we could think of connected to the suspension and steering today. We found nothing was loose or even looked too terribly worn except for the driver side sway bar link. So I replaced that today but and I drove it after the repair the thumping was still there. And when I say something it literally sounds like someone is hammering my floorboard. I've looked at my tires and they don't look bad but I will check them again. And tomorrow when I can get to my car I will take a recording of the sound, maybe that will help narrow it down to what it might be. I just don't want to keep fixing things that aren't the problem.
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Sunday, September 6th, 2020 AT 7:32 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

I totally understand and respect what you said. If it isn't broke, don't fix it. LOL

If it is that bad, it shouldn't be too hard to find. Can you tell which side it's on? Also, do you hear it at all when you are parked or stopped at a light?

If not, it has something to do with the rotation of the tires. Suspect a tire, wheel bearing, or something that is turning when the vehicle is moving.

Let me know.

Joe
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Sunday, September 6th, 2020 AT 8:15 PM
Tiny
SHANANAGANS75
  • MEMBER
  • 3 POSTS
I have one more thing to add, it doesn't get louder or quieter when I turn the wheel right or left, or when I put pressure on the brakes. It completely stops and when I am at stop. It literally only make sound in motion.
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Saturday, September 12th, 2020 AT 12:52 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

Based on your last post, it sounds like it is a tire issue. Have you checked for a shifted belt? Also, have you been able to record the sound?

Let me know.
Joe
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Saturday, September 12th, 2020 AT 7:24 PM

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