Rebuilt Turbo, now VGT's stuck between 0-40%

A

aiyoung97

New member
Feb 16, 2025
2
0
1
Charleston, WV
Hey everyone,

2007 Classic LBZ, rebuilt the turbo last fall and ever since rebuilding, my VGT's are not working properly. Took it to my buddy's shop who has a Tech 2, and the VGT's only show 0-40%, will not open any further. I did not have VGT issues prior to rebuild, turbo had some play in it so I took it apart to fix.

Here's what I did/did not do:

I did attempt to take apart the VGT portion of the turbo while I had it off, but did not have any luck. (I removed the VGT position sensor, and the snap ring/cover hiding the "rack" gear. I could not get the cover to come off to gain access to the spur gear, so I called it quits and moved on with the rebuild. Unison ring and vanes were fairly clean, cleaned everything up, made sure the vanes moved freely and reinstalled the unison ring. Put the turbo back together, and now we are here...

Where did I go wrong? is it possible to install the unison ring incorrectly? Could the rack gear have moved out of place while I was rebuilding and slid back in a few teeth off since I had the cover/snap ring off? If so, is it possible to take the cover back off with the turbo installed in the truck and realign?

If I have to pull the turbo, so be it, but want to gather what info I can before doing so.

Thanks everyone
 
diesel-max

diesel-max

Haisley Never heard of her
Oct 20, 2011
173
16
18
IN
You possibly have the half gear from the unison ring driveshaft off from the plunger portion it works off of. To remove the aluminum plug, remove that snap ring and if I remember correctly it’s a m8 bolt or a 6.0psd intake manifold bolt works great lol that will thread in and use a pair off needle nose pliers and bolt to pry it out.

There is a hole in that plunger you can use a pair of snap ring pliers to go in and expand out so you can slide it to check movement. Unless you have it apart though it would be hard to reset properly if it is off.

Make sure you do not have a bad VPS as well if it was changed at the same time as the rebuild or maybe a fluke thing.
 
SoCalMike

SoCalMike

Active member
Dec 12, 2010
851
79
28
California
I believe it is an m6x1.0 bolt that you can use to screw into that cover and remove it. I'm about to rebuild my turbo also.

It could be a couple of problems that the OP has and thats the reason I was saying to pull the turbo and go over it again. There are a couple of videos that can help him out to put et back together properly.


Sent from my SM-S928U using Tapatalk
 
A

aiyoung97

New member
Feb 16, 2025
2
0
1
Charleston, WV
Thanks for the response guys, I did not replace the VPS - put the factory one back on. While I had access to the tech 2, I did pull the VPS off and manually press in the plunger on it to check that it was reading correctly on the tech 2. It went 0-100% as it should. I guess its time to pull the turbo back off... Oh well, lesson learned. Thanks everyone
 
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