This post will list the pros and cons of the LLY Duramax engine. The LLY was an update to the LB7 and created some buzz in the diesel aftermarket. Now you could always find a list of Cons on the internet, but this article is going to focus on both positives and negatives. So without further adieu, here are the LLY Duramax engine pros and cons.
What is LLY Duramax?
The ILLY DURAMAX is a turbocharged diesel engine. It was first introduced in 2004. The “DURAMAX” name is taken from the Duramax line of engines that were used in GM’s trucks, which are petroleum-based engines.
The Duramax LLY, as it is known, has a displacement of 6,664 cc (403.9 cu in) and produces about 310 hp @ 3,000 rpm. The engine uses a variable geometry turbocharger to reduce lag and improve engine response at low speeds.
It has common rail fuel injection and an electronically controlled unit injector pump with a solenoid injector to deliver fuel directly into each cylinder’s combustion chamber.
This type of injection allows precise delivery of fuel at high pressures and temperatures without using conventional port injection systems. The Duramax LLY is rated at 380 lb·ft (515 N·m) at 1600 rpm with an exhaust gas temperature of 2300°F (1260°C).
What is lly Duramax? The lly Duramax is a turbocharged, intercooler, inline-6 diesel engine manufactured by General Motors (GM) and marketed under the Duramax nameplate. It is used in light trucks, vans, and SUVs. The lly Duramax was introduced in 2001 for use in the Chevrolet Colorado/GMC Canyon mid-size pickup trucks.
The 6.6 L version of the engine was first used in 2004 as an option on the full-size Chevrolet Silverado 2500/3500 pickups and has been available in that vehicle since 2005.
Are LLY Duramax Reliable?
The LLY engine can last 150,000 to 200,000 miles before needing any major repairs or replacement parts. The only problem with these engines is injector harness issues and they have a high oil consumption rate which means that they will use a lot of oil while driving around town or on long trips.
This is not really an issue though because the oil consumption rate is less than 1 quart every 1000 miles which are actually very good for an automotive diesel engine. Generally, they are pretty reliable.
In fact, a lot of people have made it past 200K miles on them with no problems. The first thing you need to do is make sure that you service your truck when it is due.
LLY Duramax Pros
The LLY Duramax engine is one of the most reliable diesel engines made by GM. It has been proven to last over 150,000 miles without major problems.
The LLY Duramax has 310 horsepower and a whopping 605 lb/ft of torque at 1,600 RPM. This means that you can tow almost anything with this engine. Even more impressive is how it gets that power to the ground: with a 6-speed Allison transmission that shifts smoothly and quickly.
The LLY Duramax has some minor issues but they are mostly related to things like fuel injectors or head gasket. These are easily fixable at home or by an auto shop if you have access to one nearby.
The LLY was designed to meet the stringent emissions standards of California and other states that required diesel vehicles to meet Ultra-Low Emissions Vehicle (ULEV) standards.
The LLY had an exhaust brake and a “regenerative braking” feature that could recharge the battery when coasting or braking.
The LLY Duramax is a great engine for the money. While it’s not as powerful as the L5p or newer engines, it still has plenty of torque and power to tow anything you’ll ever need.
LLY Duramax Cons
The injector harness is one of the most common problems that you will see on the LLY Duramax. The injector harness is made up of wires and connectors that allow the PCM to communicate with the injectors.
The problem with these harnesses is that they are not very durable and over time they will start to break down. This can cause a no-start condition or other driveability issues because the PCM cannot communicate with the injectors.
Another common issue with these trucks is an overheating issue when it comes time to tow something heavy. This can be from a variety of different things such as an intake manifold gasket leak, head gasket leak or even an oil cooler line leaking down low.
If you are having trouble with your truck overheating when you tow makes sure you check all these things first before replacing expensive parts like heads or intake manifolds!
Another setback is the fact that most LLY has a hard time towing over 9000 lbs This is probably one of the biggest cons about these trucks is that they have a hard time towing over 9000 lbs which means if you have a fifth-wheel camper (over 9000 lb) as we do then you’re going to have a hard time towing it, this varies greatly based on the condition of the truck.
Thomas is a retired Chevy Auto Technician, Father to two incredible daughters. He enjoys using his knowledge and experience to help you solve and find reliable information on Chevrolet vehicles.