Tech Stuff

2011 Chevrolet Silverado 2500 LTZ Crew Cab
The engine oil filter is easily accessed from underneath (left side rear of the block). The diesel fuel filter is located on the right (passenger) side, under the air intake. The most common method of access is from the right front inner fender (requires inner fender liner removal). To make this easier, you can make a cutout on the plastic fender liner for filter access, and then install a cover panel over the cutout. You can make this panel, or they’re available from various aftermarket sources. This will make fuel filter changes easier, especially in the winter months when the need to change fuel filters increases in cold climates.

The engine’s oil-fill tube is a very heavy duty steel tube, with welded bracing (we can assume that during design development, this must have posed a stress area).

The turbo, as expected, is located behind the intake area. Intake plumbing is fully accessible, but (again, as you’d expect), intercooler plumbing is deeply buried. The engine bay is so busy that you can’t even see the valve covers, so be prepared to remove a bit of real estate to gain access. The turbo wastegate is tucked way back on the right side and down low, so you’ll need long arms to reach. The access issues I’m pointing out aren’t criticisms, but merely the nature of the beast. The front lower shroud/dust cover hides quite a bit, so access to the steering box, pulleys, etc. will be much improved after removing this cover. By the way, the Allison 6-speed transmission features its own external spin-on filter, which is a nice touch.

The Duramax engine features a “common rail” fuel feed system, with a fuel rail dedicated to each bank. The CP3 type fuel pump is located at the front and is gear-driven by the camshaft. Fuel pressure is controlled by the ECM via a pressure regulator. A fuel supply pump moves fuel from the tank to a separate high-pressure pump.

One of the reasons the Duramax is so quiet is due to the use of two types of fuel injection pulses. At engine speeds from idle up to about 2,500 rpm, a “pilot” injection occurs first, spraying a small amount of fuel to start the combustion process, immediately followed by main fuel injection. This basically allows combustion to occur in a sort of stepped process instead of popping the main charge in from the get-go.

Cold weather (we’re talking cold) has always plagued diesel-fueled engines, since the fuel likes to “gel” at freezing temperatures. The Duramax (like other diesels) features feature an intake air heater (IAH) and glow plugs (one per cylinder). The glow plugs heat the combustion chambers, inviting the fuel into a cozy warm environment, free to combust as intended. (diesel exhaust fluid)

Exhaust fluid?

No, that’s not a joke. Anyone who routinely works on diesel trucks is certainly familiar with diesel exhaust fluid (DEF) by now. If you’ve never heard of this before, DEF is one of the key elements involved in the SCR process (Selective Catalytic Reduction, a system enacted starting with all 2010 diesel trucks). It is a nontoxic solution of 67.5% water and 32.5% automotive grade urea (ammonia). Simply put, DEF helps to convert NOx into nitrogen gas and water vapor. DEF is stable, colorless and odorless, and helps diesel engines meet the 2010 tailpipe standard, and supposedly increase fuel economy as well.  Small quantities of DEF are injected into the exhaust stream (plumbed to the converter). As already mentioned, when mixed with NOx, the NOx converts to harmless nitrogen and water vapor. Commonly, DEF refills will coincide with engine oil change intervals. <I>If the DEF is allowed to deplete (not refilled when needed), engine performance may degrade and the engine may not start.</I>

The DEF fill neck on the 2011 Duramax-equipped Silverado is located on the right side of the firewall. The fill neck features a bright blue cap and a very convenient built-in funnel to reduce the chance of spillage.

A note of caution: Pay attention when topping off fluids. Until you’re familiar with this truck, READ the fluid fill caps. Don’t make the mistake of rushing and assuming that the blue-capped fill neck for the DEF is for the tranny, windshield solvent or anything else.  If you accidentally dump trans fluid into the DEF fill, you’re gonna have big problems, and you’ll probably kill the expensive converter.

Engine    Duramax 6.6L Turbo Diesel
Transmission    Allison 6-speed automatic & electronic shift transfer case
GVW rating    10,000 lbs.
Rear axle    3.73:1 ratio & locking rear differential
Front suspension    Independent, torsion bar
Rear suspension    Multi-leaf (Z85 handling/trailering)
Steering    Recirculating ball
Brakes    4-wheel disc ABS

MISC. FEATURES (this list does not include all vehicle features)
Diesel exhaust brake
Tire Pressure Monitoring System (does not apply to spare tire)
20-inch forged aluminum wheels
LT265/60R20 tires
Adjustable pedals
Stabilitrak stability control with trailer sway control and hill start assist
125-amp alternator
Cruise control
Rear vision camera system (in-mirror video)
Camper style heated/power adjustable door mirrors
Battery run-down protection
Oil life monitor system

PERFORMANCE SPECS
Horsepower    397 @ 3,000 rpm
Torque    765 ft.-lbs. @ 1,600 rpm
Max conventional tag towing    17,000 lbs.
Max 5th wheel towing    21,700 lbs.
Max payload    4,192 lbs.
Max front gross axle weight rating    6,000 lbs.

DURAMAX ENGINE SENSORS

MAF (Mass Air Flow)

IAT (Intake Air Temperature)

CKP (Crankshaft Position sensor). This is located on the front engine cover. 57X signal.

CMP (Camshaft position sensor). Also at the front engine cover. 3X signal.

ECT (Engine Coolant Temperature sensor)

BP (Boost Pressure sensor). Placed inside the intake manifold. Serves as a MAP sensor.

FRP (Fuel Rail Pressure sensor)

FT (Fuel Temperature sensor). This is mounted in the return line, providing info to the ECM.

Low oil level sensor/switch (located in the left wall of the oil pan sump)

PAGE: 
Post a comment
 

Comments (1)

 

Post a Comment

Submit
Subscribe Today

Subscribe to Auto Service Professional

Sign up for a FREE subscription to Auto Service Professional magazine

Subscribe