duramaxperformanceblog.com – Everything You Need to Know about Duramax Diesel Engines

What are the most common LLY Duramax problems? In this post, we will be addressing this question and hopefully answer most, if not all, of your questions. The LLY Duramax 6600 liter of the year 2004 is a transitional engine. It is the stage where the engine evolved to meet the stricter modern carbon emissions controls established in the United States of America. Duramax maintained the engine’s competitiveness in the market. The 6.6-liter engine abandoned the LB7‘s fixed geometry waste gated turbocharger in favor of a variable geometry model. Is an LLY Duramax a Good Engine? The LLY is a good engine. The 6.6-litre engine is a good work truck that requires few modifications in order to enjoy undisturbed use for very long periods. Heavy-duty use of the engines in high-temperature areas requires the installation of secondary cooling systems. The Duramax engine has a maximum mileage of more than 200k. It is durable, reliable and high performing, therefore is built to last. This is why it is a favorite for tuners who love to get the best performance that they can out of it. To add to this, the engine was pretty efficient for its time in terms of emissions. If you get an older model, it won’t have stuff like EGR, which just makes the LLY more modern. How long will an LLY Duramax last? The Duramax engine is built to last. The LLY engine has been reported to have reached more than 300 000 miles of use. This is with little to no tune-ups. When religiously maintained and serviced the engines last longer. Upon reaching the 200 000 miles marker, older parts of the engine must be replaced such as the plugs and water pumps. What Are the Common Issues with the LLY Duramax? Restrictive turbo Mouthpiece The LLY engine is prone to problems which include a restrictive turbo mouthpiece. The 6.6-liter engine’s turbocharger creates a choke point just before the boosts enter the compressor section of the charger. The factory's two-piece intake Y-bridge hinders air intake and flow. Consequently, the turbocharger increases and maximizes input, increasing high operational heat. This reduces power; spool-up increases fuel use and contributes to high pressure and heat in the engine. Extremely High Temperatures The small radiator and cooling fans of the truck further contribute to the high temperatures of the engine. The turbocharger's power and airflow are restricted and this increases pressure and heat. The above issues culminate into the blow-up or going out of the head gasket in higher mileage trucks. It requires one to add a secondary cooling system to limit the chances of gasket problems. Head Gasket Issues The head gasket cannot be easily repaired since approximately 40 hours are required for servicing the gasket. 20 major engine components must be removed before the gasket can be accessed. Glow Plugs The light rods in the engine of the LLY pose a problem. Beyond 6000rwhp, the rods can bend. This is coupled with the glow plug issues which break when overloaded with electrical current during engine start. This often has bad repercussions. The engine has connection problems with the injector wire harness. The common-rail injection system has also been noted as a cause for concern for the engine in higher mileage trucks. The LLY was an improvement. The changes made increased horsepower and torque. The engine is technically identical to the LBZ. Its mechanical setup is maintained in its successor the LBZ. Bad MAF sensor A faulty Mass Airflow Sensor (MAF) can lead to a poor performance of the engine, particularly in the fuel economy department. Your LLY Duramax will consume more fuel than it should. If the MAF sensor isn’t the culprit, then you just may be behind on your tuning schedule. Faulty cam timing system Many have reported engine knocking problems in their LLY Duramax. The reason for this is a bad camshaft timing system. The indicator is when the knocking sound reduces as you drive on. Otherwise, the engine’s valves and cylinder components are the culprits. Fuel pressure relief valve The pressure relief valve on the engine’s fuel rail can go bad over time. This is due to excessive usage of its spring which reduces the pressure in the engine. This will decrease the truck’s performance. Bent rods Let’s say that you’ve added some heavier-than-usual mods to your LLY Duramax. Yes, you’ll get what you need – an increased level of power. However, this can cause the engine’s rods to bend and fail. https://youtu.be/WHPGQin13bM How LBZ Duramax Improved The changes made were guided towards increasing power and staying clear of the emissions controls. The variable geometry turbocharger is called the variable vane turbocharger (VVT). It increased throttle response. The VVT reduced turbo lag which resulted in an increase in horsepower and torque. The LLY is famed for having a larger turbocharger compared to any other Duramax engine with an 11-blade compressor wheel with exhaust vanes of 15mm. The VVT was such a success it was later used in the 2016 LML model. The 6.6 liter engine has improved serviceability through the new valve cover that exposes the fuel injectors. The LLY adopted the exhaust gas recirculation system (EGR), an endeavor to meet emissions control. The LLY succeeded the LB7 in 2004. The engine can be differentiated from its predecessor by checking the last digit of the vehicle identification number (VIN). The VIN is unique for every generation of Duramax engines. As such, the LLY of 2004 has the digit “2” instead of “1” which is the 8th digit for the LB7 Duramax engine of 2004. The successor to the LLY, the LBZ of 2006 is identified through the letter “D.” The LLY has achieved a peak horsepower of 310 in trucks with an automatic transmission system. The manual transmission system has a maximum of 300 horsepower. The Allison 1000 automatic transmission attained the 605lb-ft of torque and the ZF S6-650 manual transmission system achieved a peak torque rating of 520 lb-ft. Due to lower peak torque and horsepower ratings of the manual transmission system, manual ZF-equipped trucks are not widely sought after. The Duramax engine feels like a regression since the torque of 520 lb-ft and horsepower of 300 of the ZF manual transmission are identical to the LB7 engine models. The LB7 engine was phased out by the LLY engine in 2004. Conclusion The LLY Duramax engine is a relatively good engine that requires rigorous maintenance. It requires tune- ups when used in high-temperature areas with secondary cooling systems to account for the high temperatures produced by the engine. Compared to other models of the Duramax, the LBZ is the best engine.

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