Engine Sounds Loud At Random Times

Normally, my engine sounds fine. At random times, it sounds louder than normal. It’s not a grinding noise. It sounds more like a muffler noise issue, but the issue is random. I would’ve thought a muffler issue would be more consistent. The car display isn’t showing any issues. No flashing red or yellow icons on the dash board. The rev looks reasonable. The noise remain even when I take my foot off the gas.
Then, it’ll just go away on its own. Any ideas? Thanks in advance.

It’s a V6 Accord 2011 Sedan with auto trans

Check the condition of the exhaust manifolds and the tightness of the bolts that are holding them on. Many years ago, I had the same problem with my Volvo, and it turned out to be a small crack in the manifold. Sometimes–probably depending on the temperature–it was fairly loud, but at other times it seemed near-normal.


Does it only happen when cold? Have a friend with that, turned out to be exhaust manifold problem.

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A cracked exhaust flex pipe can do that.



It’s been 30-40 outside. It’s colder in the morning but I’ve never heard it in the morning. I’ve gunned it on the highway and saw it hit 3 on the rpm for a sec but I jumped 60 to 80mph quickly. I don’t think it’s slipping. The acceleration seems reasonable. In the morning, I do mostly highway driving. In the afternoon, I take the back roads home. I still can’t completely rule out the transmission. Thanks for the help. I hope it’s the exhaust.

Hmm, exhaust first. But the comment about only reaching 3000 RPM when “gunning” it, seems low, but that should be setting a warning light.