06 Civic, occasional pop on start and accelerate, please help

Hi, I have a 2006 Civic LX Sedan, 188,000 miles. A few weeks ago I had to have my muffler replaced. Since then, I've heard an occasional pop, or maybe thunk sound. Just a single sound, not continuous or repeating. I don't know if it's related to the muffler or not, but I never noticed it before that, and I've heard it almost every day since then.

It sometimes happens right after I turn the ignition, while the car is still stationary. It also sometimes happens when accelerating from a stop, or as I complete a turn on a city street. I haven't ever heard it when already going a moderate speed.

I took it to a shop couple days ago but they weren't able to hear the sound. It doesn't happen consistently.

I thought it was coming from the muffler, but I'm starting to doubt myself now. Maybe it is from under the hood. I've tried to look for youtube videos that sound similar, but nothing has matched.

If anyone has any suggestions of what this might be, what to look for, etc., I would really appreciate it.

Thank you very much!


Registered VIP
What was the reason for replacing the muffler? Give some background. Was just the muffler replaced?

You may want to inspect the motor/transmission mounts and the front motor torque mounts.
Well, 6-7 weeks ago while my wife was out with the car it started making terrible noises under the hood. Not knowing what was wrong, we had the car towed to a nearby shop rather than drive it even a little further. They determined that the water pump and belt tensioner needed replacing, which they did. The engine sounded fine after that, but apparently the towing caused the tailpipe to detach from the muffler, which was pretty rusted. So back at our home shop, we had the muffler replaced. Since then, I've had the issue described in my original message.

Does that give anyone any more ideas of what might be happening?

I'll mention to my mechanic your idea of the motor/transmission mounts and front motor torque mounts. Thank you for that!

I'm also going to start recording each time I drive the car, in the hopes of catching a recording of the pop to play for my mechanic.

But yes, any further ideas would be very helpful. Thank you!


Registered VIP
Did the engine overheat due to the failed water pump?

The noise problem is more likely linked to replacement of the water pump/tensioner not the muffler. Hopefully, the mechanic was smart enough to replace the timing belt during the job to save on labor costs.

To do the timing belt/water pump job, the front right motor mount must be disconnected. My guess is that the noise is due to one or more damaged mounts or the front right mount was not tightened properly. If the latter mount is damaged, the mechanic should have alerted you to the problem during the course of water pump work and asked whether you wanted it replaced to save on labor costs.


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