6.6L Duramax Turbocharger Removal Procedures

Duramax Diesel GT3788VA VGT Turbo Removal Guide

The 2004.5 to 2016 Duramax diesel utilizes a Garrett GT3788VA variable geometry turbocharger (LLY, LBZ, LMM, LML engines). The turbocharger is mounted in the engine valley at the rear of the engine, thus there are significant spacial constraints to overcome in accessing the various components for removal. Removing the turbocharger on a Duramax is a cumbersome task, but the entire process is outlined in detail below. One of the most common reasons for removing the turbocharger is to disassembly and clean the turbine housing as the VGT system has a tendency to collect soot, eventually impeding movement of the unison ring and individual vanes.

Duramax VGT Turbocharger Install Parts List

The following parts list is a "bare minimum" list of gaskets, seals, and other parts required and/or recommended to be replaced once the turbocharger is removed. See comments section to identify which parts are required, recommended, and optional.

Description

Part Number

Comments/Notes

Oil filter

ACDelco PF2232F

REQUIRED - engine oil must be changed once turbocharger is reinstalled.

Engine coolant (OEM orange)

ACDelco DEX-Cool (GM 12346290)

OPTIONAL - Engine coolant must be drained to remove turbo. If collected in a clean container, it may be reused. Part number is for OEM DEX-Cool orange engine coolant.

Crankcase ventilation hose o-rings (CCV)

-113 Viton o-ring

RECOMMENDED - use common dash number 113 oil and heat resistant o-ring (such as Viton); (2) required.

Oil supply line crush washer

GM 97331137

REQUIRED - do not reuse crush washers and/or gaskets.

Oil drain tube gasket, upper

GM 97227012

Oil drain tube gasket, lower

GM 97208191

Coolant inlet/outlet line crush washer

GM 97373522

Up-pipe to turbocharger flange gasket

GM 97192618

Up-pipe to exhaust manifold flange gasket

GM 97188685

Up-pipe bolts

DMCO 201012

REQUIRED - Do not reuse bolts; material properties and strength characteristics degrade w/ age and repeated heat cycles. Reused bolts highly likely to break and very time consuming/expensive to remove. (12)

Oil supply line assembly

GM 97374369

OPTIONAL - Replace if damaged and/or leaking.

Oil drain tube assembly

GM 97303638

Coolant inlet hose

~ 3.5" of 3/8" ID heater hose/coolant line

OPTIONAL - Reuse hose if in good condition and removed w/ out damaging. Small diameter coolant hose @ driver side.

Coolant outlet hose

GM 97383472

OPTIONAL - Reuse hose if in good condition and removed w/ out damaging. Large diameter coolant hose w/ 90 deg bend @ passenger side.

How to Remove the Turbocharger on a Duramax Diesel

Click any thumbnail to view fullsize, detailed image

lower radiator hose

• Disconnect both negative battery cables.

• Remove the passenger and driver side inner fenders (series of plastic clips).

• Secure the front of the vehicle on appropriately rated jack stands and remove both front tires.

• Drain the radiator into a clean container so that it may be reused (easiest method is to pull the lower radiator hose through the passenger side inner fender).

intake tube

• Remove the section of intake tubing between the air filter box and the turbocharger compressor inlet mouthpiece.

intake resonator removed

• Remove the intake resonator.

• Loosen the clamp for the crankcase ventilation coupler (connects left and right CCV tubes to intake tubing at compressor inlet mouthpiece).

intercooler pipe removal through inner fender, Duramax diesel

• Remove the driver side intercooler tube (hot side). It will need to be maneuvered out through the driver side fender; be cautious not to snag any of the various electrical harness components. The intercooler boot clamps require an 11 mm deep socket.

CCV hose

• Trace the CCV hose to the passenger side valve cover. Remove the 8 mm bolt securing the hose retainer to the valve cover fitting. Gently rotate the hose left-to-right while pulling upwards to remove it from the valve cover fitting.

• Repeat for the driver side CCV hose (it is a mirror image of the passenger side, albeit with less room to work).

• Remove the CCV coupler from the intake tube at the turbocharger inlet and set the hose assembly aside.

turbocharger mouthpiece

• Remove the turbocharger intake mouthpiece (single Marmon clamp).

glow plug controller connectors

• Disconnect the glow plug controller connectors (driver side of turbocharger near firewall). The left connector has two knurled tabs 180 degrees apart; press the tabs, then pull out the connector. The right connector has a retainer that slides towards the driver side, then the connector can be pulled out.

• Remove the glow plug controller with a 10 mm socket (2 bolts).

glow plug controller removed

• Remove the glow plug controller heat shield. (4) bolts require a 12 mm socket and the single bolt at the fuel line requires a 10 mm socket.

glow plug controller bracket removal

• Remove the glow plug controller bracket with a 12 mm socket. There are (2) bolts at the front of the bracket and (1) hidden behind the foot of the bracket. The rear bolt will require a box end wrench as a socket will not fit.

turbo heatshield removal on 6.6L Duramax diesel

Remove the (3) bolts securing the heat shield to the top of the turbocharger with a 10 mm socket. Bend and/or cut the heat shield as necessary to remove it from the engine compartment. It CANNOT be removed without bending or cutting; it is common to cut the corner off the shield on the passenger side to allow for easy removal and installation.

• Disconnect the electrical connector for the vane position sensor and maneuver it through the wiring harness. Remove the protective heat shield by cutting the band clamp around the sensor. Finally, remove the vane position sensor (a special socket, such as Schley SCH12400, is required to remove the sensor).

transmission dipstick tube bracket

• Locate the transmission dipstick tube bracket behind the turbo downpipe. Loosen the (2) nuts with a 13 mm socket/wrench. Once loose, pull the bracket up and over the bolts so that the dipstick tube and bracket float freely. The bracket is slotted such that the nuts do not need to be removed entirely, just loosened.

• Remove the (3) bolts securing the downpipe heat shield using a 10 mm socket. Pull the heat shield out from behind the turbocharger; it will not fit past the framerail if you attempt to remove through the fender.

6.6L Duramax diesel downpipe removal

• Loosen, then remove the Marman clamp securing the downpipe to the turbocharger turbine outlet with a 12 mm deep socket. Using a 11 mm deep socket, remove the Marman clamp securing the downpipe to the exhaust pipe.

• Remove the clamp securing the downpipe to the passenger side exhaust manifold using a 14 mm socket.

• Remove the downpipe, maneuvering it through the hood (it will not fit through the fender opening). These tend to be stubborn; rotate the downpipe up and down to free it from the turbine outlet. Have patience, it will come out from behind the turbo.

up-pipe heat shield

• Remove the driver side up-pipe heat shield; it is secured with (4) bolts requiring a 10 mm socket. You will need to feel for the bolts as space is limited and you will not physically be able to "see" all of them.

• Remove the driver and passenger side up-pipes from the turbocharger turbine housing inlet. There are (3) bolts per up-pipe, all requiring a 12 point, 12 mm socket. The head of the bolts is only accessible with a 12 point socket.

These bolts are extremely stubborn. The best method of accessing them is through the passenger side inner fender. Use a large breaker bar to break them loose while a helper holds the socket on the bolt. Do not be surprised if 1 or more of the bolts breaks. You may find it useful to soak the bolts in penetrating oil overnight before attempting.

6.6L Duramax up-pipe removal

• Remove the driver side up-pipe from the exhaust manifold using a 12 point, 12 mm socket. Again, this is easier with two people as space is limited and you do NOT want to strip the head of one of these bolts as they are difficult to extract. Let the up-pipe float in place, it only needs to be moved to access the oil drain line.

• Remove the (2) bolts securing the oil drain tube to the engine block with a 12 mm socket.

turbo oil feed line banjo bolt

• Remove the oil feed line banjo bolt and sealing washers from the top of the turbocharger using a 14 mm socket.

• Remove the VGT solenoid (actuator) using a 12 point, 8 mm socket. The bolt is located at the bottom of the bracket.

turbo pedestal bolt, passenger side

• The turbocharger pedestal is secured to the engine block using (3) bolts, all requiring a 17 mm socket. The bolt on the passenger side is easily accessible.

turbo pedestal bolt, rear

• The rear pedestal bolt on the driver side of the turbocharger is also easy to access.

turbo pedestal bolt, driver side

• The front most pedestal bolt on the driver side is extremely difficult to see, let alone reach. You will need to use a swivel socket or universal swivel joint and a series of extensions to reach the bolt. See fullsize image for bolt location details.

The pedestal bolts can be stubborn and you may need a breaker bar to apply enough force to break them loose.

AC compressor

• Use a 1/2 drive belt tensioner tool to relieve the belt tensioner, then slide the serpentine belt off of the AC compressor; it does not need to be moved entirely.

• Disconnect the (2) electrical connectors from the AC compressor.

• Remove the (4) bolts securing the AC compressor to its bracket using a 15 mm socket/wrench.

AC compressor moved out of the way

• Carefully move the AC compressor out of the way, letting it rest between the alternator and the air filter box. Do NOT kink the AC lines; refer to image for clarification.

turbo coolant drain line

• Disconnect the turbo coolant outlet line (90 degree hose towards passenger side of compressor housing). This line is typically brittle and may be difficult to remove; it can be cut and replaced.

turbo coolant feed line

• Disconnect the turbo coolant inlet line (driver side of compressor housing). This line is typically brittle and may be difficult to remove; it can be cut and replaced.

• Maneuver the turbocharger out of the vehicle. This is much easier with two people, as one person can monitor the oil drain tube to ensure it does not become entangled with another component. While it is a tight squeeze, it WILL come out!

turbocharger oil feed line

• With the turbocharger removed from the engine, remove the oil feed line with a 14 mm socket so that the sealing washer can be replaced prior to reinstallation.

Turbocharger Installation

Reinstallation of the turbocharger is precisely reverse of removal. Be sure to replace the oil feed sealing washer and clean the gasket mounting surface for the oil drain tube at the rear of the engine. Do not reuse any gaskets; see parts list above for applicable gasket/seal part numbers. Torque specifications are listed below; note that exhaust components may need to be re-torqued after completing several drive cycles. Once the turbocharger has been reinstalled, the bearings must be prelubed before attaching the oil feed line. To do so, pour a 1/2 to 1 cup of new, clean motor oil into the oil feed hole at the top of the bearing housing while rotating the compressor wheel.

Duramax Turbocharger Torque Specs

Component

Torque Spec (in-lbs)

Torque Spec (ft-lbs)

AC compressor

---

37 ft-lbs

Turbocharger oil feed banjo bolts

---

19 ft-lbs

Turbocharger oil drain tube nuts

89 in-lbs

---

Up-pipe to exhaust manifold flange bolts

---

39 ft-lbs

Up-pipe to turbocharger flange bolts

---

39 ft-lbs

Turbocharger pedestal bolts

---

80 ft-lbs

Turbocharger heat shield

89 in-lbs

---

Turbo coolant line banjo bolts

---

19 ft-lbs

Intercooler boots

71 in-lbs

---

Glow plug controller

89 in-lbs

---

Glow plug controller bracket

89 in-lbs

---

Downpipe bracket nut

---

39 ft-lbs

Downpipe clamp

---

11 ft-lbs

Downpipe to exhaust system clamp

---

11 ft-lbs

PCV tube bolts

35 in-lbs

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