Does anyone know if the unison ring on the Garrett GT3877VA Turbo is the same as the stock one? Getting high and low boost codes so its time to pull and clean the turbo. I just want to get a unison ring to have on standby just in case. The turbo is only 3 years old so I dont think the unison ring will need to be replaced but you never know. Thanks

 

I really doubt youll need a ring for it. You could go to gpopshop.com and get the info there. Or give them a call. Great people to work with.

 

it sounds like something is sticking, it's usually either the valve or the vanes.
I'd test the actuating valve first and see if it is working properly since this can be done without going through all the labor that goes with removing the turbo.

 

Thanks for the replies. @steelhead2 I doubt I need a ring either but I would hate to be caught with my pants down just in case. This is my daily driver so I cant afford to wait for parts. I will call gpopshop.

@ Benchwrench... Yeah I am hoping just a deep cleaning will take care of it. It broke down on the freeway in December and while waiting for AAA I got sideswiped so it was in the body shop for the last two months so I am pretty sure it is just gummed up from that. I should have told the body shop to drive it like they stole it a couple times while it was there. And yes I will definitely check the actuating valve first but I am pretty sure I need to pull and clean the turbo. I drive it hard and on a hot tune a lot.

 

the only reason why you would need a second unison ring is if the one in the turbo is cracked.
if it's not cycling properly usually you will have some type of symptoms such as lack of power, smoke- white or black, and surging due to coking deposits.
checking your codes will give you an idea where to start.
you can also peck around in the tech folder for more thorough info.

 

So I was throwing both overboost and underboost codes. My VGT% was cycling back and forth from 85% and 15% and I was having low power symptoms too so I pulled the turbo to clean it and the unison ring looked ok but there was a lot of carbon build up everywhere especially around the vanes. There were definitely spots that the vanes were hanging up. I wire wheeled it and I cleaned it up really good and put it all back together and success. Runs great now. The unison rings were exactly the same by the way for anyone who is looking for this answer. Thanks for the replies everyone.

 

" My VGT% was cycling back and forth from 85% and 15%"

Can you expand on this? Was it cycling randomly, or was it going from low to high as you would expect from computer commands as if the computer was requesting a normal setting for whatever condition the engine had at that time? VGT% is the requested percentage opening, so I wonder if the computer was continuing to request a "normal" opening, or if it went wild in some way?

Brian