VNT turbo disassembly, replacement, or how to repair stuck turbo vanes

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This article shows how to disassemble the VNT mechanism for cleaning on a VW Jetta TDI.

Note - turbo housing removal and VNT disassembly requires at least basic mechanical experience and tools.  You are not disassembling the turbo CHRA so you don't need to index the wheels or balance them.  Basic definitions: CHRA - center housing rotating assembly - this part holds the oil fittings, bearings, and turbo wheels.  Turbine/intake side is the aluminum side.  Compressor/exhaust side is the cast iron side.  For more details on how a turbo works and parts, see 1000q: turbocharging FAQ.

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The VNT lever on the outside is welded to a lever inside the turbo housing.  This lever rotates the ring inside the turbo and moves the VNT vanes.  See the below videos to see how smooth and free the lever should move.  It should not stick or bind at all.  Vacuum is being applied to the can, not pressure.

Here is how the lever and ring move the vanes.

Sometimes the lever can wear down into the ring and cause it to get stuck or not respond correctly.

In these pictures you can see the extra play between the lever and the ring.  The ring repair procedure is shown below.

Innotec turbo cleaning kit or Easy Off oven cleaner method to clean a stuck TDI turbo

In some cases, oven cleaner or the innotec turbo cleaning kit will successfully free the turbo vanes. While it could be applied to the exhaust side on a cold and non-running turbo, it's better to remove the turbo from the car to ensure that all of the cleaner is removed (rinse with water), clear the oil lines of any cleaner that got into the bearings, and inspect operation of the turbo afterwards. Sodum Hydroxide (Lye) is the active ingredient in oven cleaners - refer to your product's MSDS for safey precautions. Lye pits and stains aluminum so only use the cleaner on the exhaust side to free up the vanes. You don't want to get any of it on your skin or have it splashing around while you work underneath the car. NaOH (Lye) contact can cause chemical burns to exposed skin or blindness if it gets in your eyes. See the TOS Agreement for the full legal disclaimer. If it gets on you, rinse with water and contact a medical professional.

Removal Procedure

Remove the turbo and cover the oil feed and drain lines.  I also suggest covering the compressor side openings with tape and cleaning the exterior of the turbo.

Remove the actuator (2x 10mm) bolts and remove the circlip holding the VNT lever to actuator rod.  I suggest getting a spare clip since these can fly off during installation.

The turbo housing will be rusted to the CHRA so soak the exterior of the turbine side in PB Blaster or liquid wrench.  Tilt the turbo and fill the inside of the turbine side with PB Blaster too.  This will penetrate the joint from the inside and preclean/loosen a lot of the soot buildup inside.  Let it soak for a while and tap it to help the lubricant penetrate.  If it's really stuck then let it soak overnight.

Once it's soaked and penetrated, you may notice that the VNT lever may move freely.  Don't be fooled into thinking "problem solved" because the ring inside sticks and it's range of movement won't clean the area where it sticks - you'll still need to disassemble the turbo to clean it.  Remove the 5x 10mm bolts holding the housing to the CHRA.  The two bolts without washers hold the actuator bracket.

Now separate the turbine housing/exhaust manifold from the CHRA.  The joint is highlighted with a dash red line below....

....the rest of the labeled pictures and detailed notes are for premium forum members only!  Please join our community and upgrade your account here for $2: . The exact forum post where this procedure is continued is here.  

Have more questions or have some tips about the turbo on your Volkswagen TDI?  Post your comments in the VW TDI forums.