unmuffled engine noise only in 1st gear

Hey yall, not sure if this is the right place for this, but I figured I’d give it a shot.

When I accelerate from a stop, I hear what sounds like unmuffled engine noise that sounds like it’s coming from near the front of the car. It’s not a complete roar like the muffler fell off but it’s way louder than I’m used to. After I hit 2nd gear (automatic) the noise essentially stops and it sounds normal again. The sound can’t be reproduced in neutral. I inspected what I could and the exhaust line is rusty but doesn’t appear to be broken. I also don’t see any issues with mileage.

Anyone have any ideas?

And if this isn’t the right place, can someone direct me to the right place?

Jeep Grand Cherokee 2012 Automatic V6

ironhydroxide,

My bet is: Motor mounts are weak, causing engine to rock excessively under load, rocking caused an exhaust donut to wear excessively, when under load the engine rocks enough to lift the donut from it’s sealing surface and leak.

Test: put the engine in drive, parking brake on, left foot hard on the brake. Press accelerator to load the engine. Does it leak? Try reverse (loading the engine in the opposite direction) if it still leaks it’s only load dependent not rocking dependent.

foofiepie,

My first thought was a manifold crack but thought I’d search your brand, and it led me to a page with numerous reasons. Nothing obviously specific for low gear, but I did skim read so may have missed it. Upshot is most of these things are ‘will get worse if you ignore it’. https://atvhelper.com/why-is-my-jeep-running-loud-common-causes-and-how-to-fix/

5oap10116,

Thanks for the response. It also doesn’t make the noise unless I hit the gas if that helps. I guess I’ll get it looked at given your tentative general prognosis.

foofiepie, (edited )

Is it only ever on acceleration regardless of gear?

Edit: I’ve found what might be an interesting thread. V6, 2012 mentioned. Could be as simple as the heat shield. Have a look (with an adblocker): https://www.wranglerforum.com/threads/rattling-sound-on-acceleration.190186/

5oap10116,

Only when accelerating in 1st gear. Once I get past that, it stops. If I stay in 1st gear and pump the gas, it only happens when I pump the gas. It does not happen when I Rev in neutral or when stopped at a light

foofiepie,

The thread mentions low rpm so it might be relevant.

Whoops why did my comment clone itself. Never mind.

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