Here’s What Owners Report Most Often

About two decades after the launch of the 6.6-liter Duramax V8, GM’s 3.0-liter Duramax inline-six turbodiesel arrived in 2019 with a promise to deliver “outstanding fuel economy, great horsepower, and responsive torque.” Those have been fulfilled so far, with the engine producing up to 305 horsepower and 495 pound-feet of torque. In its most efficient guise, the 3.0 Duramax averages a goodly 26 mpg, so it’s little surprise that it found its way into a handful of GM models, including the Chevrolet Silverado 1500, Suburban, Tahoe, GMC Sierra 1500, Yukon, and Cadillac Escalade. Later, it dropped the diesel ahead of the 2025 model year due to insufficient demand.

We found the oil burner to be perfectly pleasant when we drove a 2024 Silverado ZR2 with the 3.0-liter Duramax engine, as it suffered no turbo lag and convinced with its smooth power delivery and willingness to deliver plenty of low-end torque. Not to mention, the Duramax diesel engine can tow up to 13,300 pounds — it gets a maximum rating of 8,700 pounds when beneath the hood of the ZR2 — meaning it could be a very capable towing option if you’re looking to pull large boats or travel trailers. It’s a fine engine, but it can experience a number of problems, with some owners taking to discussion sites to complain about issues most commonly linked to the diesel exhaust fluid (DEF), oil leaks, and frustrating crank start issues.

According to a Silverado Sierra forum post from Smell-U-Later, the 3.0 Duramax diesel engine can experience long cranking times on start up — up to 10–20 seconds. Many drivers admit they had encountered this problem at least once, with their vehicles either taking a long time cranking before starting or refusing to start altogether. One owner of a 2021 Silverado 1500 RST 3.0 Duramax Turbo Diesel, Brian, while commenting on Car Complaints, noted that this problem is intermittent and can happen randomly at any time and at any mileage.

Faulty camshaft position exciter wheel is one of the most common reasons for the 3.0 Duramax engine long cranking time issue. Some factory-fit camshaft position exciter wheels in certain Chevy Silverado 1500, Tahoe, Suburban, GMC Sierra, Yukon, and Cadillac Escalade models are said to arrive bent or warped. In such state, they can disrupt the signals being relayed to the engine control unit (ECU), thus impacting the timing of fuel injection. Usually, fixing this issue requires replacing the camshaft trigger wheel, a job some owners have said takes 40 hours or more to complete, as it often involves taking the cab off to allow for proper access. 

Damaged camshaft position exciter wheel aside, the Duramax LM2 is known to have issues with bad wiring harness, loose or faulty fuse box, faulty actuators, and defective fuel pumps. All of which can also contribute to the extended cranking time trouble. In some cases, the issue is solved through an update or software refresh of the engine’s ECU. Another bit of good news is that this problem affects only the first generation LM2 Duramax 3.0, and not the second-gen LZ0 variants introduced in the 2023 Chevrolet Silverado half-ton truck.

Like nearly any combustion engine, the 3.0 Duramax inline-six has a rear main seal (RMS), a component that’s designed to stop engine oil leaking through around the crankshaft. However, some owners have reported that the 3.0 RMS is prone to failure, and that it often develops leaks as a symptom. Leaks can be slow or very fast, to the extent that engine oil levels get dangerously low before drivers have time to top up or visit a mechanic. A GM TSB claims this issue occurs primarily due to the rear main oil seal moving or severely shifting out of position in the timing chain lower cover, and thus recommends replacing the timing chain lower cover as a fix. Sadly, some have complained that the oil leak problems keep coming back even after repair.

Diesel exhaust fluid (DEF) system faults are something else that 3.0 Duramax owners commonly face. Drivers have complained about their vehicles suddenly developing DEF malfunction and displaying the “Service DEF System” message along with an engine warning light. In most cases, limp mode comes on immediately the message is displayed and limits power to avoid further damage to the engine. Some owners have found this to be a symptom of either bad def injector, loose DEF hose, or faulty DEF sensors, but in other cases, mechanics don’t find any issues with the engine, despite DEF warning suggesting possible faults.