2018 2.7 rattle from what sounds like turbos/wastegates.
I’ve searched and found similar rattle, but no one seems to have the answer.
Seems that once it warms up, it goes away.
Any ideas?

 

check heat shields under the cats and muffs,
I had to add a hose clamp to where a tack weld broke to silence mine

 

Was able to use stethoscope, it’s transmission. Sounds like tranny fluid pump is grinding.

 

That sucks. Good news, it should be under the powertrain warranty.

 

It sure does.
I hope dealer gets me sorted.

 

Wow that's super interesting. I posted a while back about a similar sound and everyone who responded said look at the exhaust etc. I can tell mine is mechanical in nature. It only happens when driving under a slight load though, never at idle. Usually hwy speeds.
Is this what you experience as well?
Sounds like mine, lasts 2 to 4 seconds then immediately stops with a metallic clank.

 

Not an exhaust noise. 99% sure it’s the mechanical transmission fluid pump. It happens in cold start up and also when up shifting when cold.. once warm, it still happens just not as loud

 

Update:
Took the truck to dealer, was able to replicate noise, says normal, charged me $288 to ‘diagnose’ transmission and sent me on my way.
Fast forward a few weeks, and noise got progressively worse. It sounded like steering pump starving for fluid. Also was driving on highway and it exhibited super rough shifts, 1-3 shift felt like getting rear ended.
Called dealer back, brought the truck in again. They told me they’re dropping tranny pan.
Called me again, they’re replacing valve body, filter, gasket and other misc parts associated with valve body replacement.
Im glad dealer was able to find the problem, i thought it was the fluid pump in the transmission, because it sounded exactly like power steering pump starving.
Full disclosure, I don’t know for sure it’s the fix as I don’t yet have the truck. I’m told it’ll be either ready by tomorrow or Monday, will update then as well.

 

Good luck, hopefully it fixes it. I certainly would take my $288 receipt in, insisting on a refund, that's BS.

 

Thanks.

My thoughts exactly, but not holding my breath on the refund. Honestly, I’m just glad they did something at this point, because there were no codes, and it drove fine most of the time.
I’ll bring it up, but as said before, will not actively pursue refund, not worth my time. As is I’ve wasted too much time with back and forth calls and driving.