Why does nobody talk about the weird hum a 6.7 Powerstroke makes when the EGR cooler is about to go?

Had a truck in the bay yesterday from a farm outside Spokane, owner said it just felt 'off'. No codes, no smoke, but there was this low hum around 1800 RPM that sounded like a bad bearing. Spent three hours checking everything before I pulled the EGR valve and found the cooler fins were almost completely clogged with soot. The hum was exhaust gas trying to squeeze through a pinhole. Has anyone else heard that specific noise before a failure, or was this just a weird one-off?

2 comments

2 Comments

the_joel17d ago

We had a similar hum on a 6.4 last month that turned out to be the turbo unison ring sticking. It's wild how these motors develop their own little warning sounds before something lets go. Makes you listen to every little noise in the shop now.

graywright17d ago

Yeah that part about motors having their own warning sounds is so true. It's like they're trying to tell you a secret before they blow up. @the_joel, after your 6.4 story, I bet you jump every time a toolbox closes too loud now. You start hearing phantom hums in your sleep. These trucks turn us all into paranoid mechanics listening for the next expensive tick or buzz.