Cummins ISX CM871 Turbo problems

[hongo88]

Greetings Everyone,

I am having issues diagnosing a problem with a VGT. This is the story and I thank you in advance for any type of help: This truck had 2 camshafts, all valve guides and injector o rings replaced due to oil found at fuel and exhaust port. VGT was replaced as well because it was licking oil from seal and I opted to install a used one that I found for a good price locally. This used turbo was calibrated using insite and it passed both test. After installation a force regen was done to check if turbo was opening more that 80% to create enough heat to start regen and it did. After a successful regeneration, truck was put on the road and worked for about one and a half months and turbo stopped opening more than 50%, therefore, I took actuator out and check the end play of the leg and it was seized. I concluded and that was probably my mistake, that used turbo was bad from the beginning and that's why it gave up in such an early time and I didn't do any further testing :s. I ended up installing a re manufactured from a local dealer and again did all the same procedure and it worked like a charm, no complains from driver etc. Now 2 months later, same thing happens, turbo it only opens gate to 55% is not seized, but it don't open enough to make regeneration. What could be causing this problem?

Any help is good. Thank you in advance.