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6.6L Duramax Clogged VGT Turbo Cleaning Procedures (Garrett GT3788VA)

Time:2018-11-07 14:07Turbochargers information Click:

stuck turbo Dura clogged turbo

6.6L Duramax Turbo Removal Guide (2004-2016, LLY, LBZ, LMM, LML)

Duramax Turbocharger Disassembly & Rebuild Procedures

VGT Actuator/Piston Gear Indexing, 6.6L Duramax Diesel (Garrett GT3788VA)

6.6L Duramax VGT Solenoid Replacement (VGT Actuator)

6.6L Duramax Vane Position Sensor Replacement

When a turbocharger's VGT system becomes mechanically stuck, the corresponding effects on performance depend on the position in which the vanes stick - fully open vanes will cause the turbocharger to build pressure slowly, hindering low end performance. Vanes that stick in the fully closed position would provide good spooling characteristics off-idle, but with a loss of airflow at higher engine speeds and the potential for an overboost/overspeed condition. In reality, the vanes tend to freeze somewhere in-between the open and closed positions, causing poor overall performance characteristics, excessive turbo lag, and noticeable exhaust smoke under load. Since the turbocharger is coming apart, we recommend new bearings and seals in addition to a thorough cleaning and reassembly with anti-seize; see: 6.6L Duramax GT3788VA turbo rebuild procedures

Note - the VGT vanes and unison ring can be cleaned and reused. However, any component that is damaged (bent, excessively marred, or otherwise out-of-shape) must be replaced. Part numbers are posted above for your convenience.

Duramax GT3788VA VGT Turbocharger Cleaning (Freeing Stuck Vanes/Unison Ring)

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bearing housing

• It is highly recommended that a conditioning disc (3M Roloc 07480 has become the industry standard) be used in lieu of sand paper or other harsh abrasives. The Roloc discs will remove soot, oil, and other buildup without damaging the base material.

• Use conditioning discs to thoroughly clean the face of the bearing housing (turbine side), removing all buildup from the mating surfaces. Pay careful attention to the contact area between the unison ring and the housing as this is commonly where the unison ring becomes stuck.

turbine housing

• Use conditioning discs to thoroughly clean the contact area between the turbine housing and the individual VGT vanes. This area should be clean and smooth when finished so that the vanes move free of obstruction.

• Clean the flange where the bearing housing attaches to the turbine housing so that the two components mate easily during reassembly.

VGT vane that has been cleaned

• Thoroughly clean each individual VGT vane with conditioning discs. 3M Roloc conditioning disc and cleaned VGT vane pictured.

• Thoroughly clean the unison ring.

using bur tool on bearing housing

• Once all components have been cleaned with a conditioning disc, you may need to deburr the unison ring contact surface. The most common cause of a malfunctioning VGT system is the unison ring becoming stuck at this surface.

deburring bearing housing

• A common bur tool can be used to finish cleaning the contact ring.

cleaned bearing housing surface for unison ring

• Deburr/grind/condition the contact area (vertical and horizontal surfaces) until the unison ring rotates freely when installed in the bearing housing.

Duramax Turbocharger Unison Ring, VGT Vane Indexing & Installation

turbine housing coated in anti-seize

• Apply a liberal coating of high temperature anti-seize to the turbine housing where the VGT vanes sit.

Note - A high temperature, nickel based anti-seize must be used. Permatex 77124, Loctite LB 8009, and Motorcraft XL-2 are all suitable and can withstand temperatures up to 2,400 degrees F. Do NOT use a standard, non-heat rated anti-seize on any turbocharger components.

VGT vanes installed

• Install all VGT vanes on their respective pins in the turbine housing.

indexing unison ring in turbine housing

• Now it's time to index the unison ring (find and mark its proper location within the turbine housing).

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