I have a 2014 E350 that is making this deep gurgling/bubbling sound while the engine is idling. That’s the best way I can describe it. I’m not sure if it had always been like that but I’ve just now noticed it. Doesn’t sound right..
Car seems fine and everything is normal.

Any ideas what to check? It sounds like there’s a giant soup boiling under my hood lol

Can you record and post?

I tried with my iPhone and just couldn’t hear it due to the poor mic or it just wasn’t obvious with all the other engine noise.
Anyway, I found the root cause of the issue. My dip stick popped up again, about 3 inches. Sound goes away once the dipstick is capped.
I know another member had an issue with his dipstick popping up too.. I guess I have the issue as well.