Replaced muffler, new thump?

NIOZZIA

MEMBER
2012 NISSAN SENTRA
110,000 MILES

I recently had my muffler replaced due to hole/rust. I had an aftermarket muffler installed as it was the cheaper option. Well now when I start my car there is a single loud thump noise, when the engine catches. It doesn’t make noise when running, just as soon as it starts. I heard it as soon as I started it in the mechanics parking lot. I went back and asked him about it. He said it was due to the aftermarket muffler. Is that a possibility? Or should I go back to the mechanic and insist on getting it fixed. My car didn’t make the noise before getting the new muffler installed.

Saturday, September 19th, 2020 AT 9:02 PM

3 Replies

JACOBANDNICKOLAS

MECHANIC
110,133 POSTS

Hi,

Chances are something needs adjusted. When the engine is starting, it likely kicks a bit which can cause the exhaust to move. If the system was reinstalled too close to a component under the vehicle, it can hit.

Have a helper start the engine while you (safely) watch under the vehicle to identify where the noise is coming from. Watch near the muffler to see if you notice it moving.

Also, when the vehicle is cold, grab the exhaust at different points and shake it to see if you can recreate the sound.

Let me know if this helps. Also, if I installed it and there was a noise, I would fix it. I don't know what kind of relationship you have with the shop, but just because it's an aftermarket muffler doesn't mean it should hit under the vehicle. They really should readjust it to prevent it.

Let me know if you have other questions.

Take care,
Joe

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Saturday, September 19th, 2020 AT 9:23 PM

NIOZZIA

MEMBER
2 POSTS

Joe,

Thank you so much for your insight! I will try this week with my husband to see if we can identify where the noise is coming from. It doesn’t rattle when it drives though, just a thump when turning on.

We just moved to the area, so no relationship with this new mechanic. I went by good reviews. But I think I will for sure be going back there to get it adjusted.

Thank you so much for your response!

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Sunday, September 20th, 2020 AT 6:37 PM

JACOBANDNICKOLAS

MECHANIC
110,133 POSTS

Hi,

You are very welcome. Let me know what you find or if you have other questions. If I don't hear back from you, please feel free to come back anytime in the future if you have questions or need help.

Take care,

Joe

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Monday, September 21st, 2020 AT 5:59 PM