loud tinkling rattle from engine at idle

[Left Coast Geek]

I chose to upgrade my 2016's Sync3 and Nav maps tonight after dark, when the temps cooled down from the 95F high today to a sane low 60s/upper 50s. The maps update required letting the truck idle in my driveway for nearly an hour. When I went back out there, there was quite a loud tinkling sort of rattle, seemingly from the front of the engine. I popped the hood and didn't see anything obvious, no leaks or anything. It did NOT sound like tappet noise, or cylinder pinging, engine temps were nominal, nor did I smell anything out of the ordinary. If anything, it sounded like a chain rattling.

It was too dark out there to see much, I'll give it a better eyeball tomorrow.

 

[Mr Big]

I chose to upgrade my 2016's Sync3 and Nav maps tonight after dark, when the temps cooled down from the 95F high today to a sane low 60s/upper 50s. The maps update required letting the truck idle in my driveway for nearly an hour. When I went back out there, there was quite a loud tinkling sort of rattle, seemingly from the front of the engine. I popped the hood and didn't see anything obvious, no leaks or anything. It did NOT sound like tappet noise, or cylinder pinging, engine temps were nominal, nor did I smell anything out of the ordinary. If anything, it sounded like a chain rattling.

It was too dark out there to see much, I'll give it a better eyeball tomorrow.

Could it be coming from the turbo?

 

[Left Coast Geek]

Dunno. Not sure I can even see the turbos on this thing without removing engine covers.

 

[Left Coast Geek]

I know videos don't really work well for diagnostics, but here's the rattle.

2024-07-06 2019 3.5L Ecoboost rattle

www.youtube.com

 

[Fastcar]

Grab a 2 foot extension, put one end on the turbo and the other against your ear. A poor mans stethoscope

 

[Left Coast Geek]

I tried a hardwood dowel, about 1/2" in diameter with a domed end, about 2 feet long... inconclusive. I note the pitch and speed of the rattle does NOT change with engine RPM, so now I'm really wondering wtf this is.

 

[apex96]

Sounds like the AC clutch/ idler pulley going south… turn the A/C on HI and then off and see if the noise stops.

 

[Left Coast Geek]

no AC vs Max AC, no change in the sound

 

[Left Coast Geek]

I tried putting it in drive with the brake on and a bit of gas, nada change. ditto in 4A and 4L, revving it to 2000 rpm or so (4L wouldn't go higher at a hard stop), no change other than the clack sound of the 4L engaging/disengaging (while in N, of course)

 

[DCaretaker]

There used to be a heat riser valve in the exhaust manifold that could produce that sound. Don't know if these high tech engines still have them.