The 6.0 Powerstroke turbo have problems with the factory VGT turbo. The bearing housing and turbo housing commonly rust, which traps the VGT system unison ring. The rust will expand and make the nozzle ring difficult to move. When the unison ring stops moving the vehicle will be very difficult for it to make boost at lower rpm or higher rpm depending on the position that the nozzle ring is stuck in. This is an easy fix with the proper tools. I used a media blaster to remove all of the rust, there are also chemicals that are used to remove rust that work well. I use the media blaster and pressure was the bearing housing very well. There are a lot of oil passages on the 6.0 turbo so it is very important to clean the bearing housing very well if it is blasted. If you dont feel comfortable blasting turbo I suggest buying a new turbo here.
After I remove the rust, i paint the surface to prevent rust from coming back to cause problems. Rust is the cause of the problem, if you can prevent the bearing housing from rusting, the life of the turbo is dramatically increased. If the vehicle is continued to operated with the unison ring trapped, the VGT arm and the unison will wear out as a result causing the need for replacement. Here you can find a replacement unison ring.
