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Discussion Starter · #1 ·
Wasn't sure if I was going to post this here or not but my oil cooler thread seemed to be quite popular so maybe this will help others who are looking to rebuild their Garrett VGT turbo on their Duramax.

I can only seem to post 10-pictures at a time so this will be a multi-post thread.

I had experienced an intermittent P2563 code and after determining my wiring, connectors and everything else was in proper order, I figured I had either vanes hanging up OR a seized unison ring in the turbo, however I was not experiencing the P003A code nor the reduced power or driveability issues that most people seem in conjunction with a P2563 code.

I purchased a rebuild kit with the 360-degree thrust washer as well as a stainless steel unison ring from KC Turbo. I have no relationship with them and feel the kit is similar to many others I found online.

While I was ordering parts I purchased a new GM hydraulic actuator solenoid as well as GM gaskets/seals and all new ARP exhaust fasteners. I try not to reuse exhaust fasteners when at all possible and I have had great results with ARP fasteners over the past 30+ years of using them in many stock and race applications.

Here the truck is racked with the passenger's front tire/wheel removed and inner fender for access.
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A little tip or trick when removing barbed style connectors is using a small socket that is about the same size as the hole in the bracket, place the socket over the barb and push. It will push the barb right out of the bracket undamaged. One of my pet peeves is popping the hood on something and seeing damaged or destroyed barbs on connectors.
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Once you push the socket over the barb simply push the connector off the bracket and there's no damage. This was the vane position sensor being removed using a 1/4" drive 1/4" shallow socket.
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Progressing along by removing the serpentine belt and moving the A/C compressor over out of the way near the passenger side battery tray.
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The next item seems to be controversial, the turbo heat shield. It will not come out in one piece with the cab in place. It is common practice among many to toss it in the garbage but I am not a fan of that option. I used my small pneumatic saw to cut through the narrowest section and in a straight line then remove in two pieces.
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Easy peezy.
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At this point go ahead and start removing the downpipe heat shield and downpipe. Then soak the exhaust fasteners with your favorite flavor of penetrant. I'm a Kroil fan so I soaked the exhaust fasteners before calling it a night.
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Next using a 12-point 12mm socket start removing all of the fasteners for the passenger's side up-pipe. I then removed the upper and lower bolts on the driver's side up-pipe. Many people won't remove the entire driver's up-pipe but it's only three more fasteners and it makes the oil drain line access SO much easier for removal and especially for reassembly.
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With both up-pipes removed it's time to unbolt the pedestal bolts at the turbo. Two are not to bad to get to but the driver's side front one is a bit more cumbersome and will require a 17mm swivel socket and extension reaching down between the center section and turbine housing.
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More pictures to follow.....
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Discussion Starter · #2 ·
Continuing on....

Before continuing I took a little time to modify the OEM turbo heat shield to be reinstalled back into the engine bay by making some tabs and welding them to the larger half of the shield.
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The heat shield being two thin pieces of material with heat absorbing fibrous material sandwiched in between them, I opted to fold over a piece of 18-gauge sheet metal in two areas that will not interfere with the turbo casting.
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Once pressed over the shield, I cut two small tabs and drilled/tapped them to the same 6mmx1.0 to match the OEM heat shield fasteners.
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Tabs were then TIG welded to the sandwiched pieces and the smaller piece of heat shield was clearanced to match.
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Test fit on the turbo.
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Turbo apart and issue found. The unison ring was seized onto the center support. Vanes were not terrible but will get a good cleaning as well. The turbine impeller shaft had evidence of oil so I am glad a new oil control ring was included in the kit. Be careful cleaning the turbine wheel and impeller if you will be reusing as they are very fragile. Also worth noting is that the impeller is left hand thread requiring a 17mm socket while the turbine side of the shaft requires a 7/8" socket to hold.
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Center support as well as turbine shaft and impeller soaking to clean as much off chemically vs. having to clean mechanically.
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They came out of the solvent tank very nicely cleaned. Even the unison ring looked good although I have a new one that will be going back in.
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This part seems to be often skipped but I feel if you're this far into it you may as well go all the way. I drove the small roll pin out and removed the unison ring pivot shaft and gearset. After removing I cleaned the carbon off of it as well and prepped for reassembly.
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The piston for the hydraulic actuator is not available through Garrett or GM that I know of so I measure and sourced them through McMaster Carr as well as the 3mmx26mm spiral wound spring pins. I prefer the spiral wound spring pins to the single split roll pins in highly critical applications. Here are the McMaster Carr part #'s.
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More posts to follow shortly.....

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Discussion Starter · #3 ·
Continuing on with the turbo rebuild.

The casting flash was terrible and ultimately what caused the unison ring to seize up. I was surprised when I disassembled the turbo that the mating surface of the center section where the unison ring rides wasn't a machined surface. I would have expected it to have gone through a last machining process prior to assembly but they simply threw the unison ring down directly onto the rough casting and barely enough clearance when cold, let alone when this things gets hot. 🤔

So this is after some time with a fine rotary bit running around the two planes of the mating surface of the unison ring to open up the clearances a bit. Also I have reassembled the gearset and unison pivot shaft using a new spiral wound spring pin shown above.
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Test fitment of the unison ring to ensure it moves smoothly.
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Next was to prep the turbine housing by hitting the casting flash with the same rotary bit to smooth things out and ease reassembly. I used a 1" diameter Roloc disc to smooth the flat area where the vanes reside as well.
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Final assembly with some nickel anti-seize on the vane pivot pins as well as the flat mating surface of the vanes. Before mating with the center section I applied a small amount of nickel anti-seize to the center section where I removed casting to mate with the unison ring.
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Turbine shaft installed with new bearings, 360-degree thrust washer, oil control ring and O-rings. Impeller is torqued onto the turbine shaft using left hand rotation to 10 ft/lbs. then the compressor housing O-ring can be installed and finally the outer compressor housing can be installed and torqued to 12 ft/lbs.
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Turbo completely rebuilt and awaiting installation into the engine bay.
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Turbo in place and making sure everything is properly aligned before installing fasteners.
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This is the main reason I removed the driver's side up-pipe, so that the oil drain tube can easily sit down on the studs without having to twist and manhandle the components around. It was well worth removing the 3 remaining fasteners on the driver's up-pipe to ease the oil drain line fitment. I put the gasket over the studs before placing the turbo in place then the oil drain tube fell right into place.
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Now final step to install the turbo can be tackled. Just the reverse of previous steps. Torque the pedestal bolts to 80 ft/lbs.
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Don't forget to secure the oil drain line and torque to 15 ft/lbs. It's tight but a torque wrench will fit up between the cab and passenger head.
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More pics to follow.....
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Discussion Starter · #4 ·
Continuing on...

While the turbo was on the bench being rebuilt and before I assembled it I took a few minutes to chase the threads for all of the fasteners on the turbine housing, then I also chased the threads in the exhaust manifolds to accept the new ARP fasteners. Taking a few minutes to do this will greatly ease the assembly by having the ability to fully thread the fasteners in by hand before torqueing.

Here I am just using my Lisle tap sockets and a stubby flex ratchet to chase the threads in the driver's exhaust manifold.
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Prepping the new ARP fasteners with nickel anti-seize (2400-degree) along with the new GM exhaust gaskets at the ready.
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Driver's up-pipe fasteners started and run in by hand.
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With the up-pipe to turbo gasket in place and fasteners installed these get torqued to 39 ft/lbs.
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Up-pipe to exhaust manifold fasteners also get torqued to 39 ft/lbs.
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With the up-pipes installed and torqued to spec. along with the heat shields it was time to go top-side. Once the glow plug relay bracket and module are secured back in place I installed my slightly modified turbo heat shield. I highly recommend putting the heat shield back in place. Not only does it cut down on underhood heat but it keeps the heat in the turbo which is needed for efficient turbo operation. Trust me the manufacturers don't spend a dime more than they don't have to and if they didn't think the heat shield was needed they wouldn't have installed one from the factory. That's just my opinion so take it for what it's worth.
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While I had the cooling system empty I opted to replace the thermostats with new GM ones as it has been quite a while since they were replaced.
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Old thermostats out and new ones installed.
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Torque the thermostat housing to 15 ft/lbs. when reassembling.
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Before I finished the assembly to the top of the engine I pulled a vacuum on the cooling system. I like to confirm there are no issues with any of the cooling system components that were disconnected and if so, I'd rather find out before everything is buried. I replaced both coolant hoses on the turbo with new as well as had the thermostat housing off and the lower radiator hose was disconnected to drain the coolant. The system pulled down well and I valved it off and walked away for a while to ensure there were no leaks. I generally give it about 20 minutes or so but I got doing other things and ended up letting it sit for about an hour. It held perfectly so no leaks.
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More to follow....
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Discussion Starter · #5 ·
Continuing on.

This step is not necessary but I felt it was needed. My battery trays had seen better days so I took some time to bead blast and paint them before reinstallation.

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They bead blasted very nicely.
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I also bead blasted the tray mounting fasteners so I could paint them.
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The battery trays after a thorough application of POR-15. I hung them to let them cure overnight.
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The mounting fasteners received several coats of E-coat primer.
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The POR-15 is thick and nasty and to aid in reassembly I chased the threads for the mounting blocks.
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Everything was cleaned with Power House prior to reassembly. Here are the glow plug module and mounting bracket before installation.
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While I had the air box out I took some time to clean the area using Zep Power House. It cleaned up very well. No one will ever see these areas but I'll know they're clean.
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Final pictures to follow...
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Discussion Starter · #6 ·
On to the final pictures of the process.

I also like to verify there are no leaks in the intercooler system as it's going back together. I connected my Kent Moore pressure tester to confirm all is good with no leaks.
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The airbox also got a thorough cleaning before installation.
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The duct work after cleaning.
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Intake system completed and cooling system still holding vacuum. I then hooked up the pickup tube for the vacuum manifold and pulled a full charge of coolant into the cooling system.
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Everything back together less the resonator. I also broke off my small 1/8" nylon line feeding the dash mounted boost gauge so I took a few minutes to repair that while pressure testing the intercooler system.
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Prepping for first start.
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While the inner fender was removed and fuel filter readily available it got replaced at this time as well.
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As did the spin-on transmission filter.
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Completed and after a test run. Purrs like a kitten again and no leaks.
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Passenger's inner fender reinstalled and all tires rotated and torqued back on.
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That concludes the turbo removal, rebuild and reinstallation on our 2006 2500 HD Silverado.

Thank you for looking.


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AWESOME how to thread! 👊👍

So when can I drop my LBZ off for the same treatment?
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Discussion Starter · #15 ·
Great write-up and thank you for sharing on the forum. It will definitely help other members if they want to take on the challenge!
Thank you and that was the reason for sharing here, to help others if they wish to tackle this job. I hope others find it helpful.


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Discussion Starter · #16 ·
If anyone is interested I posted a couple of videos to my YouTube channel that I hope will be helpful to anyone either going through an R&R of a turbo or a full rebuild.

Here is the Removal and Reinstallation of the turbo into our 2006 Duramax truck.

And here is the full rebuild of the turbo once it was out and on the workbench.

Thank you and I hope these are helpful.

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