2004 6.0 VGT Unison Ring Actuator Cam - Diesel Forum - TheDieselStop.com
6.0L Power Stroke Engine and Drivetrain Discussion of the 6.0L Power Stroke diesel engine and drivetrain in the 2003-Up Super Duties and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.0L Power Stroke engine.

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post #1 of 3 (permalink) Old 01-10-2019, 06:28 PM Thread Starter
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2004 6.0 VGT Unison Ring Actuator Cam

Hello everyone. 3 months ago I pulled/cleaned my turbo from 2004 F350. I couldn’t verify VGT vanes we’re stuck once opened but everything pointed towards that. Reinstalled turbo after cleaning and truck ran great for 3 months. After a week of sitting, drove truck and same condition occurred. Lost all power and tons of black smoke. Pulled EGR, cleaned it. It was still clean from 3 months earlier. So I just pulled turbo again, other than some common black soot, everything is pretty clean. I noticed the pin/cam that actuates the VGT piston if rotated to far to the left (vane closed) position, it seems to get stuck and won’t rotate back to the right without some effort when using the unison ring to rotate it. If I just cycle the pin/cam, it is pretty smooth. I pulled the piston out to see if it was getting jammed and the no change. I noticed the actuator piston was missing both seals. This is the second turbo Ford installed and it says remanufactured. If I use a magnet to push piston back and forth, unison ring is smooth. Watching videos I see the unison ring rotating back and forth without any hang ups and trying to determine if this may be my problem. Unable to find replacement seals and hesitant to reinstall turbo without finding anything wrong. Anyone else experience this problem? Sorry for long post.
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post #2 of 3 (permalink) Old 01-12-2019, 10:28 AM
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Did you start the gear engagement on the first tooth of the sliding rack? As long as it doesn't get hung up in the range of motion of the the sliding rack (plunger?) allows it should be ok, even though if you can rotate the ring past the action of the actuation arm. The seals, I don't know, never saw them offered.
There could be a "notch" or wear spot, in the ring's slot where the actuating arm runs causing a hang up but you would think a just "factory" re-built turo would not have that issue. Another thought is the lack of seals causes the piston to lose pressure making the actaution pressure marginal and now the least thing, like sitting up for awhile, can allow a stick.
Thinking aabout those seals, I am not sure, even if you can find them, you can install them. It may not be straight forward as they are hard and don't look very flexible and therefore not easy to strecth and then shrink back to fit in the groves. I would try to find a new rod and piston or a used one.
If it were me, I'd order a build kit that has all the seals ( it won't have the ones on the plunger) and maybe, just to be sure include a new unision ring. and a new or used plunger. The seal kit is usually less than $50 and the ring and vanes might be another 100 or so.

Last edited by hammer30; 01-12-2019 at 10:33 AM.
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post #3 of 3 (permalink) Old 01-14-2019, 06:51 PM Thread Starter
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Thanks for feedback Hammer30. Yes, I made sure the 1st tooth was engaged. The range of motion looks good. I have looked everywhere for those seals with no luck. My concern was same as yours, possibly not getting enough oil pressure to actuate the vanes. But it’s pretty clear that the seals were never installed and I am starting to notice with other online videos that possibly the seals are not being installed on refurbished models. This turbo was installed by Ford almost 3 years ago and up until recently, no major issues with it. Although I was concerned about the unison ring locking up when I rotated it by hand over center, I realized that when exercising the piston with a magnet, (simulating oil pressure) it operates smooth and doesn’t hang up at all.
I will definitely start looking for a replacement piston, the seals would be nice, just not available anywhere that I could find.
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  Diesel Forum - TheDieselStop.com > 1999-2007 Ford Super Duties > 6.0L Power Stroke Engine and Drivetrain

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