Bulletin No.:

Service Bulletin

Date:

19-NA-180
September, 2019

INFORMATION
Subject:

Brand:

Chevrolet
GMC

Duramax® Diesel 3.0L New Engine Features

Model:

Model Year:
From:

Silverado
1500

To:

2020

Sierra 1500

Involved Countries

From:

To:

—

Engine:

Transmission:

Duramax®
Diesel, 3.0L,
Inline
6-Cylinder, CRI,
DOHC,
Turbocharged,
VGT,
Aluminum,
CSS50V —
RPO LM2

10L80,
10-Speed
Automatic,
ATSS, CPA,
GEN 2 —
RPO MQB

United States, Canada, Mexico, South America and Middle East

Overview
Bulletin Purpose
The purpose of this bulletin is to introduce the
Duramax® diesel 3.0L turbocharged engine. This
bulletin will help the Service Department Personnel
become familiar with the engine, components, fuel
system, engine oil requirements, exhaust
aftertreatment system and transmission.

Duramax® Diesel 3.0L L6 Turbocharged
Engine — RPO LM2
Overview
The Duramax® Diesel 3.0L will be paired with GM’s
10-speed automatic transmission — RPO MQB and will
produce approximately 282 horsepower (210.28 kW)
and 450 lb ft (610.11 Nm) of torque.

Copyright 2019 General Motors LLC. All Rights Reserved.

VIN:

Page 2

September, 2019

Bulletin No.: 19-NA-180

5336795

Left Front

Bulletin No.: 19-NA-180

September, 2019

Page 3

5336810

Right Front
Engine Specifications
•
•
•
•
•
•
•

Bore: 3.307-inches (84.0 mm)
Compression: 261 PSI (1800 kPa)
Compression Ratio: 15:1
Displacement: 3.0L
Firing Order: 1–5–3–6–2–4
Glow Plug Voltage: 5.4 V
Stroke: 3.543-inches (90.0 mm)

•

•

Engine Component Description
•
•

•

•

Camshaft: Two camshafts are used, one for all
intake valves, the other for all exhaust valves. The
camshafts are driven by two camshaft sprockets
which in turn are driven by the secondary timing
chain.
Compressor Air Intake Turbocharger: The
turbocharger is a variable nozzle design with an
electric vane actuator attached to the exhaust
manifold. The turbocharger supplies compressed
air from the turbine/impeller to the engine to
increase power. It also results in higher fuel
efficiency and lower CO2 emissions.
Crankshaft: The crankshaft is forged steel with
4 counterweights. It is supported by 7 main
journals with main bearings which have oil
clearance for lubricating. The thrust bearing is

•

•

located at the 6th main journal. A crankshaft pulley
is used to control torsional vibration. The sprocket
for the primary drive chain is machined directly on
the crankshaft. An oil pump sprocket is integrated
on to the crankshaft along with a timing
reluctor ring.
Cylinder Head: The cylinder head is dual
over-head camshaft (DOHC) with 4 valves per
cylinder. The cylinder head is made of cast
aluminum.
Engine Block: The engine block is cast
aluminum with 6 pressed in iron sleeves. The
block has 7 crankshaft main bearings with one
thrust bearing set.
Exhaust Manifold: The exhaust manifold is
located on the cylinder head. It is designed to
endure high pressure and high temperature. The
turbocharger is mounted on the exhaust manifold.
High Pressure Diesel Fuel Injection System:
The high pressure fuel pump supplies pressurized
fuel through the high pressure fuel lines to the fuel
rail and then through the fuel injector lines to the
fuel injectors. Excess fuel returns to the fuel tank
through the fuel return pipes.
Hydraulic Valve Lash Adjuster: The valve train
uses a valve rocker arm acted on by a hydraulic
valve lash adjuster which reduces friction and
noise.

Page 4
•

•

•
•

•

September, 2019

Intake Manifold: Intake air flow from the throttle
body passes through the intake manifold to the
cylinder combustion chambers. The intake
manifold is made of a composite material.
Lower Crankcase Extension: The lower
crankcase extension bolts to the engine block and
contains the oil pump. The oil pump is fastened
directly to the lower crankcase extension. The oil
pump is a variable vane pump driven by a wet
timing belt, which is driven by the oil pump
sprocket.
Lower Oil Pan: The lower oil pan is made of
dual-layer stamped aluminum and is attached at
the lower crankcase extension.
Positive Crankcase Ventilation System: The
positive crankcase ventilation (PCV) valve carries
blow-by gas to the turbocharger inlet of the intake
system. The amount of blow-by gas varies
according to engine conditions, driving conditions
and the pressure of the turbocharger. The PCV
valve is designed to control the amount of
blow-by gas.
Valves: There are 2 intake and 2 exhaust valves
per cylinder.

Bulletin No.: 19-NA-180

Cooling System
Overview
The Duramax® 3.0L utilizes GM’s advanced cooling
system strategy known as Active Thermal Management
(ATM). ATM distributes coolant through the engine in a
targeted manner, sending heat where it’s needed to
warm up the engine, thereby reducing friction. It
promotes quicker heating of the passenger
compartment as needed and engine cooling when
needed during high power operation. The system uses
a conventional engine-driven coolant pump. The ECM
controls the complete ATM system using feedback from
various sensors.
The engine has numerous engine coolant temperature
(ECT) sensors placed at specific locations throughout
the cooling system as follows:
– Engine Block Coolant Temperature Sensor
– Engine Cylinder Head Coolant Temperature Sensor
– Engine Inlet Coolant Temperature Sensor
– Engine Outlet Coolant Temperature Sensor
– Radiator Outlet Coolant Temperature Sensor
– Heater Core Inlet Coolant Temperature Sensor
– Heater Core Outlet Coolant Temperature Sensor
Additional sensors used by the ECM to control the ATM
system are:
– Engine Oil Temperature Sensor 1 and Sensor 2
– Transmission Oil Temperature Sensor
– Control Valve Sensors

Bulletin No.: 19-NA-180

September, 2019

Page 5

Engine Coolant Flow Control Valve

5340159

The Engine Coolant Flow Control Valve assembly is
attached to the engine under the intake manifold. The
engine coolant flow control valve is comprised of two
actuators, the Block Rotary Valve (BRV) (1) and the
Main Rotary Valve (MRV) (2). The engine coolant flow
control valve consists of two chambers. The first
chamber controls the coolant flow rate across the
radiator and bypass. The second chamber controls the
flow to the transmission and engine oil cooler, providing
heated coolant from the EGR/Turbocharger return
circuit or cold coolant directly from the pump outlet, as
required based on feedback from the various coolant
temperature sensors. The engine coolant flow control
valve also has an integrated Flow Control Valve (FCV)
(3) that limits engine coolant flow from the mechanical
water pump when full output is not needed. The
Exhaust Gas Recirculation (EGR) feed port is
always open.

Engine Coolant Flow Control Valve Reverse View

5354588

1. Block Port
2. Head Port

Page 6

September, 2019

Bulletin No.: 19-NA-180

Exhaust Aftertreatment System

Auxiliary Electric Engine Coolant Pump

Overview
The exhaust aftertreatment system is designed to
reduce the levels of hydrocarbons (HC), carbon
monoxide (CO), oxides of nitrogen (NOx), and
particulate matter (PM) pollutants remaining in the
engines’s exhaust gases before they exit via the
vehicle’s exhaust tailpipe.
Typically NOx and PM are controlled by separate
aftertreatment components. NOx is controlled by a
Selective Catalytic Reduction (SCR) converter
combined with precise injections of Diesel Exhaust
Fluid (DEF), while PM is controlled by a diesel
particulate filter (DPF). Combining aftertreatment
system components can reduce packaging volume and
manufacturing cost. One way of doing this is to coat the
SCR catalyst on the DPF to form an SCR coated DPF
also known as a Selective Catalytic Reduction on Filter
(SCRoF).
5340434

When the Stop/Start System has shut down the engine,
and the ambient temperature is colder than 59°F
(15°C), the ECM will activate the Stop/Start relay for the
auxiliary electric engine coolant pump motor (1) to turn
it ON. This will continually circulate engine coolant
through the heater core while the engine is OFF. This is
to ensure the passenger compartment temperature is
maintained while the engine is OFF. Once the Stop/
Start System has restarted the engine, the ECM will
deactivate the relay to turn OFF the auxiliary electric
coolant pump motor, allowing the engine driven coolant
pump to circulate the engine coolant.

Bulletin No.: 19-NA-180

September, 2019

Page 7

Component Location and Description

5336000

Tip: A exhaust mounting boss is an internally threaded
protruding feature on a work piece or component,
typically used to mount various exhaust sensors. In the
diagrams the boss is used to identify certain
component mounting locations.
1. Nitrogen Oxides (NOx) Sensor - Position 1 (Boss).
2. Emission Reduction Fluid/Diesel Exhaust Fluid
(DEF) Injector Mounting Flange.
Note: This catalyst is located in the close coupled
position.
3. Nitrogen Oxides Catalytic Converter (LM2 With
Filter) assembly. The arrow points to the Diesel
Particulate Filter (DPF) section of the assembly
(rear gray section), that contains the SCR on Filter
(SCRoF).
4. Exhaust Back Pressure Valve. The valve disc is
internal to the assembly and the valve actuator is
mounted on the exterior cover.
5. Nitrogen Oxides (NOx) Sensor - Position 3 (Boss).

Note: This catalyst is located in the underfloor
position.
6. Nitrogen Oxides Catalytic Converter (LM2 Without
Filter) assembly. The front section of the assembly
is an SCR. The rear section of the assembly is an
Ammonia Oxidation Catalyst.
7. Nitrogen Oxides (NOx) Sensor - Position 2 (Boss).
8. Diesel Oxidation Catalyst (DOC), part of the
Nitrogen Oxides Catalytic Converter (LM2 With
Filter) assembly. The arrow points to the Diesel
Oxidation Catalyst section of the assembly (front
green section).

Page 8

September, 2019

Bulletin No.: 19-NA-180

Component Location and Description
(Reverse View)

5336140

1. Exhaust Temperature Sensor - Position 1 (Boss).
2. Emission Reduction Fluid/Diesel Exhaust Fluid
(DEF) Injector Mounting Flange.
3. Exhaust Pressure Differential Sensor Pipe.
4. Exhaust Pressure Differential Sensor Pipe.
5. Exhaust Gas Recirculation (EGR) Flange.
Note: This catalyst is located in the underfloor
position.
6. Nitrogen Oxides Catalytic Converter (LM2 Without
Filter) assembly. The front section of the assembly
is an SCR. The rear section of the assembly is an
Ammonia Oxidation Catalyst. The arrow points to
the SCR section of the assembly.
7. Particulate Matter (PM) (Boss).
8. Exhaust Back Pressure Valve. The valve disc is
internal to the assembly and the valve actuator is
mounted on the exterior cover.
Diesel Oxidation Catalyst (DOC) Operation
The DOC is the front section of the Nitrogen Oxides
Catalytic Converter (LM2 With Filter) assembly. The
close coupled DOC removes exhaust HC and CO
through an oxidation process. The DOC functions much
like the catalytic converter used with gasoline fueled
engines. As with all catalytic converters, the DOC must
be hot in order to effectively convert the exhaust HC
and CO into CO2 and H2O. On cold starts, the exhaust
gases are not hot enough to create temperatures within

the DOC that are hot enough to support full HC and CO
conversion. Proper DOC function requires the use of
ultra-low sulfur diesel (ULSD) fuel containing less than
15 parts-per-million (ppm) sulfur. Levels above 15 ppm
will reduce catalyst efficiency and eventually result in
poor driveability and one or more DTCs may be set.
Selective Catalyst Reduction (SCR) — SCR on Filter
(SCRoF)
The close coupled DOC along with the SCR on Filter
(SCRoF) are integrated into one assembly. The
combined SCR and DPF make up the second section
of the Nitrogen Oxides Catalytic Converter (LM2 With
Filter) assembly. In the DPF, particulate matter
consisting of extremely small particles of carbon
remaining after combustion are removed from the
exhaust gas by the large surface area of the DPF. DEF
is injected into the exhaust gases prior to entering the
SCRoF stage. Within the SCRoF, NOx is converted to
nitrogen (N2), carbon dioxide (CO2) , and water
vapor (H20) through a catalytic reduction fueled by the
injected DEF.

Bulletin No.: 19-NA-180

September, 2019

Emission Reduction Fluid — Diesel Exhaust
Fluid (DEF)
Note: Depending on the Service Information or
Parts Information that is being referenced,
Emission Reduction Fluid is also identified as
Diesel Exhaust Fluid (DEF) and/or Reductant.
Diesel Exhaust Fluid (DEF) is a mixture of a carefully
blended aqueous urea solution of 32.5% high purity
urea (Pharmaceutical Grade Urea) and 67.5%
deionized water. The ECM energizes the DEF injector
to dispense a precise amount of reductant upstream of
the SCRoF in response to changes in exhaust NOx
levels. Within the SCRoF, exhaust heat converts the
urea into ammonia (NH3) that reacts with NOx to form
nitrogen, CO2, and water vapor. Optimum NOx
reduction occurs at SCRoF temperatures of more than
480°F (250°C). At lower temperatures, NH3 and NOx
may react to form Ammonium Nitrate (NH4NO3) which
can lead to temporary deactivation of the SCRoF
catalyst. To prevent this, the ECM will suspend DEF
injection when the exhaust temperature is less than a
calibrated minimum.
A 32.5% solution of urea with 67.5% deionized water
will begin to crystallize and freeze at 12°F (−11°C). At
this ratio, both the urea and water will freeze at the
same rate, ensuring that as it thaws, the fluid does not
become diluted, or over concentrated. The freezing and
thawing of DEF will not cause degradation of the
product. DEF should be stored in a cool, dry,
well-ventilated area, out of direct sunlight.
Exhaust Gas Temperature (EGT) Sensor
The engine uses exhaust gas temperature (EGT)
management to maintain the SCRoF catalyst within
the optimum NOx conversion temperature range of
390–750°F (200–400°C). The ECM monitors the EGT
sensors located upstream and downstream of the
SCRoF in order to determine if the SCRoF catalyst is
within the temperature range where maximum NOx
conversion occurs.
Exhaust Pressure Differential Sensor
Pressure connections, provided by pipes/hoses at the
DPF inlet and outlet allow the sensor to measure the
pressure drop across the DPF. This pressure drop
increases as trapped soot (Particulate Matter) collects
in the cells of the DPF during vehicle operation. The
rate at which soot collects varies with the power
demands placed on the engine. If left unchecked, the
increasing back pressure will eventually result in a
driveability problem. There are two sensing elements in
the sensor; one for the upstream side of the DPF, and
the other for the downstream side. Pressure from each
side of the DPF is applied to the bottom side of a silicon
diaphragm in each sensing element while atmospheric
pressure is applied to the top side of each diaphragm.
Relative pressure differences in each sensing element
is converted to a voltage (V1 & V2). The difference in
these voltages is monitored by the ECM. As the DPF
becomes restricted, the pressure on the upstream side
increases because of back pressure due to the
restriction of the exhaust gas flow exiting the DPF.

Page 9

Nitrogen Oxides (NOx) Sensor
The ECM uses three smart NOx sensors to control
exhaust NOx levels. The first NOx sensor is located in
the inlet pipe of the close coupled catalyst, near the
turbocharger outlet and monitors the engine out NOx.
The second NOx sensor is located in the exhaust pipe
downstream of the SCRoF and monitors NOx levels
exiting the close coupled SCRoF. The third NOx sensor
is located on the Nitrogen Oxides Catalytic Converter
(LM2 Without Filter) assembly and monitors NOx levels
exiting the aftertreatment system.
The smart NOx sensors consist of two components, the
NOx module and the NOx sensor element that are
serviced as a unit. The NOx sensors incorporate an
electric heater that is controlled by the NOx module to
quickly bring the sensors to operating temperature. As
moisture remaining in the exhaust pipe could interfere
with sensor operation, there is a delay turning ON the
heaters until the exhaust temperature exceeds a
calibrated value. This allows any moisture remaining in
the exhaust pipe to boil off before it can effect NOx
sensor operation.
Particulate Matter (PM) Sensor
The PM sensor monitors the amount of particulates
(soot) in the exhaust gas exiting the tailpipe. The PM
sensor is similar to a heated oxygen sensor with a
ceramic element but also includes an individually
calibrated control unit. The PM sensor sensing element
includes two comb-shaped inter-digital electrodes, a
heater and a positive temperature coefficient (PTC)
resistor used for temperature measurement.
The operation of the PM sensor is based on the
electrical conductivity characteristic of the soot. As the
exhaust gas flows over the sensing element, soot is
absorbed in the combs between the electrodes,
eventually creating a conductive path. When the path is
formed, it generates a current based on the voltage
being applied to the element. The measurement
process continues until a preset current value is
reached. To avoid misleading readings, the sensor
operates on a “regenerative” principle, where the soot
is cleaned off by heating up the element to burn off the