Why did my turbocharger seize on a Freightliner in the middle of Nevada?

I was about 60 miles outside of Winnemucca last Friday when my rig lost all power going up a steep grade. Oil pressure was fine but I could smell burnt metal as I pulled over on the shoulder. Has anyone here had a variable geometry turbo fail from carbon buildup on the unison ring?

3 comments

3 Comments

holly_reed551mo ago

From my experience working on Detroit DD15s and Volvo D13s, it's actually more likely that the variable geometry vanes stuck from soot instead of the unison ring itself. The unison ring gets blamed a lot but the real culprit is usually the vanes not moving freely because of carbon buildup from short hauls or excessive idling. I had a 2018 Cascadia last year with the same symptoms and the shop found the actuator arm was seizing too, not just the ring. You might want to check the turbo actuator before pulling the whole unit off, because on those newer Freightliners the actuator goes out and throws the vane position out of whack. Just a thought based on what I've seen on the road.

paige3311mo ago

Oh man, that's so true about the actuator! My buddy runs a fleet of Cascadias and he had one that was doing the same thing, throwing codes and losing power on hills. He spent a whole weekend fighting with the unison ring, cleaned everything up real good, put it all back together, and it still acted up. Finally he gave up and took it to the dealer and they found the actuator was shot - like, dead on arrival. Cost him way less than the new turbo he was about to order. I swear those newer Freightliners have some weird turbo gremlins that aren't always obvious unless you dig into the data.

reed.skyler1mo ago

Ha! So the moral of the story is, sometimes throwing parts at it just makes your wallet lighter and your weekend longer. "Dead on arrival" actuator, love it, that's a classic truckin' tax right there.