Best Duramax Engine: What Are the Best & Worst Years? (2022)

If you want to know the best and worst year models of Duramax engines, then you have come to the right place. The joint venture between Isuzu and General Motors (officially known as DMAX) in Moraine, Ohio, brought about the Duramax diesel engines that consist of eight-, four-, and six-cylinder engines.

The Duramax engines came in both V and inline (I) configurations, with most of its application being in Chevrolet and GMC vehicles. The older models are simpler but come with lots of complications such as overheating, head gasket failure, weak tie rods, and water pump failures, just to mention a few. The new models improved upon their predecessors, but they are more complex.

We will look at the various year models of the prolific Duramax engines. Our focus will be to highlight their features to show you their weaknesses and strengths. Stick around to learn which Duramax engines to avoid and which ones to buy.

Best Duramax Engine: What Are the Best & Worst Years? (1)

Table of Contents

  • 1 Best Duramax Engine Year Models Safe To Buy
  • 2 Duramax Engine Year Models To Avoid
  • 3 Duramax Engine: All Year Models, Applications, and Common Problems
  • 4 Conclusion

Best Duramax Engine Year Models Safe To Buy

Newer engines will not trouble you as much as the old models. When looking for a reliable machine, the phrase ‘old but goody’ does not apply. The first Duramax models, from 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, and 2010 (apart from LGH) were faced with lots of issues that will cost you a lot in terms of repairs and maintenance.

Moreover, these year models are not safe to use as newer ones due to new features such as DEF and DPF systems implemented in the 2010 to 2021 Duramax engines. You will also find out that the efficiency of Duramax LGH to Duramax LM2 is higher due to the combination of efficient systems and computerized tunes.

Best Duramax Engine: What Are the Best & Worst Years? (2)

New emission regulations were also implemented in the Duramax engines starting from 2011. The improvements made the machines more complicated but safer and drivable for longer. Emissions systems were improved in the later models by using diesel exhaust fluid and urea injection features.

Another advantage of the new 2011 to 2021 models is using after-treatment systems that enable vehicle users to tune the fuel economy. With this system, you can increase your vehicle’s fuel economy by adjusting the exhaust after treatments.

The best Duramax diesel engine year models that are safe to buy include:

  1. 2010 – 2017 Duramax LGH
  2. 2011 – 2016 Duramax LML
  3. 2011 – 2021 Duramax XLD25
  4. 2012 – 2021 Duramax XLD28
  5. 2014 – 2021 Duramax LWN
  6. 2017 – 2021 Duramax L5P
  7. 2019 – 2021 Duramax LM2

Duramax Engine Year Models To Avoid

You should avoid buying Duramax engine models from 2001 to 2010. Engines from this era are full of mechanical issues as well as durability limitations based on their build quality, the material used, and available features.

Duramax engines such as the Duramax LB7 and Duramax LLY have frequent issues that involve the fuel lift pump, fuel injectors, water pumps, head gasket, tie rods, and turbo inlet manifold, just to mention a few. It will cost you a lot to repair and maintain these engines, and their lifespan is short even if you get one new.

Avoid Duramax engine year models from 2001 to 2010, including:

  1. 2001 – 2004 Duramax LB7
  2. 2004 – 2005 Duramax LLY
  3. 2006 – 2007 Duramax LBZ
  4. 2007 – 2012 Duramax LMM

Duramax Engine: All Year Models, Applications, and Common Problems

2001 – 2004 Duramax LB7

Best Duramax Engine: What Are the Best & Worst Years? (3)

The Duramax LB7 is a Regular Production Option (RPO) code for General Motors that denotes the Duramax engine produced between 2001 and 2004. The engine consisted of Bosch high-pressure common rail direct injection system incorporated into its 32-valve design.

Its block and head were made of cast iron and aluminum, respectively. The powerful 6.6L V-8 engine produced 300 horsepower with a torque of 520 lb. ft at 1,800 rpm. It is the least functional engine of the line-up, but a turbocharger and intercooler made them formidable.

Read more: GM 4.8 Vs 5.3 Vs 6.2 Engine (With Comparison Chart)

(Video) What Is The Worst Year Duramax Ever Made? EXPLAINED!


LB7 Duramax engines are used in the Chevrolet Silverado 2500 and 3500, GMC Sierra HD 2500 and 3500, Chevrolet Kodiak C4500 and C5500, and GMC Topkick C4500 and C500 till early 2004 when they got replaced by their successor, the LLY.

Common problems

The common problems in the LB7 are the most prevalent in the Duramax engines. Customers have reported issues with the fuel injector that goes bad quickly. There is no fuel lift pump in the LB7 engines, and the water pump leaks.

LB7s also experienced overheating and head gasket failures over a prolonged period of use. Other issues with the engine include:

  • Leaking O-rings on the fuel filter housing
  • Allison 1000 transmission limp mode
  • Broken or snapped tie rods
  • High horsepower applications

Is It Good Or Bad? Should I Buy It?

Despite its powerful output and sufficient application in GMC and Chevy vehicles, the LB7 is the least recommended engine in the group. You should not buy this engine lest you end up spending a lot of time at the mechanic shop.

2004 – 2005 Duramax LLY

The Duramax LLY engines took over the Duramax engine category fully by mid-2004. DMAX improved the injectors due to so many failures in the LB7. Valve covers were improved to allow access to the fuel injectors without removing the valve covers. This helped save a lot of labor charges if you were to replace the injectors.

It used the same 32-valve design as well as Bosch’s high-pressure common rail injection. The compression ratio remained at 17.5:1, improving horsepower (310 bhp) and torque (590 lb. ft).


Best Duramax Engine: What Are the Best & Worst Years? (4)

The 6,619-cc turbocharged engine finds its application in the 2004 to 2005 Chevrolet Silverado 2500 HD and 3500 HD. It was also implemented in GMC Sierra 2500 HD 3500 HD from 2004 to 2005.

Common problems

Like its predecessor, the LLY did not fall short of many issues. Despite the upgrades, the LLY engine still had head gasket failures, water pump malfunctions, overheating of the engine, and lacked a factory lift pump.

Other issues included:

  • Turbo inlet manifold failures.
  • Injector harness chafing.
  • Glow plug failure.
  • EGR valve problems.
  • Fuel pressure’s relief valve malfunctions.
  • Suspension and steering problems.
  • Bent rods.

Is It Good Or Bad? Should I Buy It?

LLY was an improvement on the LB7 but still retained a lot of issues that will make it a hard bargain for the current market. It would be best not to buy the LLY due to its many problems and the lack of essential features like the factory lift pump.

2006 – 2007 Duramax LLY/LBZ

Best Duramax Engine: What Are the Best & Worst Years? (5)

The 2006 to 2007 Duramax V-8 engines have two VIN codes due to delays in getting EPA certification. There is Vin 2 and VIN D; VIN 2 is identical to the VIN D but uses the tunings of the LLY. VIN D was the post-EPA certification model with a computer tune for more power and torque.

Improvements include an upgrade of the primary bearing material, which improved durability. The compression ratio was modified to 16.8: 1 from 17.5:1, and the connecting rod ‘I’ was made thicker for more strength.

The engine was made quieter by the introduction of air induction systems. LLY/LBZ saw the first use of the 32-bit E35 controller for regulating fuel flow to improve efficiency and reduce carbon emissions.

(Video) The Ultimate Duramax Engine Guide (And Why It's The Best)


The first LLY inspired model from late 2005 and early 2006 was used in the Chevrolet Silverado HD. Chevrolet Kodiak, GMC Sierra HD, Chevrolet Express, 2006 Hummer H1 Alpha, and the GMC Savana. The later LBZ was applied in the Chevrolet Silverado HD, GMC Sierra HD, GMC TopKick, and the Chevrolet Kodiak.

Common problems

LLY/LBZ engines had more strength and efficiency than any other Duramax engines at the time. The only common issues in these engines include: cracked pistons, glow plug failures, EGR problems, Allison 1000 transmission line leaks, and water pump failures.

Is It Good Or Bad? Should I Buy It?

LLY/LBZ from 2006 to 2007 is considered one of the most reliable and rugged engines from the pre-emission’s era. They are widely sought out for because of this and can be a great buy if you are looking for a Duramax engine of this time. Beware that they have more issues than recent Duramax engines from 2011 to 2021.

2007 – 2010 Duramax LMM

Best Duramax Engine: What Are the Best & Worst Years? (6)

The Diesel Particulate Filter (DPF) was first introduced in the 2007 LMM Duramax engine. The engine has a 6-speed Allison transmission and features the same compression ratio as its predecessor. It comes with a V-8 configuration housed in a cast grey iron block and cast aluminum head.

The engine produces 365 horsepower at 3200 rpm and a torque of 660 lb. ft at 1600 rpm. The production of LMM brought about new engine control software and increased-capacity cooling systems.

Read more: L99 Vs LS3 Vs LS7 (With Comparison Chart)


LMM engines were used in 2007 Chevrolet Silverado 2500 HD, 2500 HD, 2007 GMC Sierra 2500 HD, 3500 HD, 2007 Chevrolet Express 2500, 3500, and 4500, as well as 2007 GMC Savana 2500, 3500, and 4500.

Common problems

The first common issue in LMM 6.6L engines is the new DPF system and active regeneration that continually malfunction. Other issues are:

  • Leaking transmission lines.
  • Fueling/low fuel pressure.
  • Piston and crankshaft failure.
  • Allison 1000 power limitations.

Is It Good Or Bad? Should I Buy It?

The introduction of the DPF system makes the LMM a compelling buy. However, it would help if you did not buy this year’s models due to the improvements and upgrades in the later models from 2011, like the LML.

2011 – 2016 Duramax LML

Best Duramax Engine: What Are the Best & Worst Years? (7)

The Duramax LML engines are also 6.6L V-8 engines with turbocharger and intercooler aspiration. These engines were made alongside the LGH and could produce 397 bhp at 3000 rpm with a torque of 765 lb. ft at 1600 rpm.


The V-8 engines were not used in many vehicles like most Duramax engines. LML was only put in the 2011-2016 Chevrolet Silverado 2500 HD, 3500 HD, and 2011 to 2016 GMC Sierra 2500 HD and 3500 HD.

Common problems

The recurrent issues of LML engines include:

  • DEF pump failure
  • DEF heater problems
  • CP4.2 injection pump failure and NOx sensor failure

Is It Good Or Bad? Should I Buy It?

LML is the first great buy among the Duramax engines we will recommend. Experts and frequent users attest to the reliability and efficiency of these engines due to the lack of previous Duramax engine issues like Allison 1000 power limitations and water pump failures.

(Video) Duramax LB7, LLY, LBZ, LMM, LML, L5P Explained!

2011 – 2016 Duramax LGH

The Duramax LGH came with a 6.6L displacement and was used before 2011, when its official production started. It can produce 335 bhp at 3100 rpm and 685 lb. ft at 1600 rpm. It also came with DPF and DEF systems to comply with the emissions standards in the country.


Best Duramax Engine: What Are the Best & Worst Years? (8)

LGH engines were put in vehicles between 2011 and 2016 and 2010 interim Chevrolet Express and GMC Savana vans. The list of vehicles includes:

  • 2011 -2016 Chevrolet Express 2500, 3500, 4500 vans
  • 2011-2016 GMC Savana 2500, 3500, 4500 vans
  • 2011-2012 Chevrolet Silverado 3500 HD chassis cab
  • 2011-2012 GMC Sierra 3500 HD chassis cab

Common problems

The only common issue with the Duramax LGH is the CP4.2 injection pump failure.

Is It Good Or Bad? Should I Buy It?

LGH engines are good engines considering they have one recurrent issue. Additionally, introducing DPF and DEF systems is great for us to recommend you buy them.

2017 – 2021 Duramax L5P

Best Duramax Engine: What Are the Best & Worst Years? (9)

The Duramax L5P marks the end of the 6.6L V-8 DMAX engines with 445 horsepower capabilities at 2800 rpm and 910 lb. ft torque at 1600 rpm.


L5P is placed in 2017 to current Chevrolet Silverado 2500 HD, 3500 HD, and 2017 to current GMC Sierra 2500 HD and 3500 HD.

Common problems

Oddly enough, the LGH has more recurrent issues than its predecessor. The issues include:

  • MAP sensor failure
  • Allison 1000 transmission limitations
  • Fuel injector failure, especially injector number 4

Is It Good Or Bad? Should I Buy It?

L5P is good, and an excellent buy for your GMC and Chevy needs.

2019 – 2021 Duramax L5D

The Duramax L5D may seem like a different engine, but it is a downgraded version of the predecessor, the L5P. The purpose was to increase its reliability while at the same time reducing the downtime. It can produce 350 horsepower at 2600 rpm and a torque of 700 lb. ft at 1600 rpm.


Best Duramax Engine: What Are the Best & Worst Years? (10)

The application includes the 2019 to current Chevrolet Silverado 4500 HD, 5500HD, 6500HD, and 2019 to current international CV series.

Common problems

Duramax L5D is very reliable and efficient, with the only common issue being the air filter failure.

Is It Good Or Bad? Should I Buy It?

Duramax L5D is a great engine which is an excellent buy in the current market. It has the latest specifications and a broad application base.

2011 – 2021 Duramax XLD25

The Duramax XLD25 is the first non 6.6L engine from DMAX. This Inline I-4 engine has a 2.5L displacement, making it smaller than any previous Duramax engine. The engines feature DOHC, four valves per cylinder, and a compression ratio of 16.5:1.


Duramax XLD25 was designed to use in:

  • Chevrolet Colorado S-10
  • Chevrolet Trailblazer for international markets
  • Mid-size pickup trucks
  • SUVs

Common problems

Vehicle owners have not reported any significant issues with the XLD25 engines.

(Video) Worst Diesel Engine Ever - What is the Best Diesel Truck out There? | Ford Dodge Chevy

Is It Good Or Bad? Should I Buy It?

Duramax XLD25 are relatively new engines with minor recurrent issues. They are worth a buy due to their extensive features and durability.

Read more: Chevy 350 (SBC and BBC) Firing Order [With Diagram]

2012 – 2021 Duramax XLD28

The Duramax XLD28 is similar to the XLD25. However, they produce more power than their predecessor, with a power output of 200 hp at 3600 rpm compared to the 163 hp at 3600 rpm of the XLD25. The bore and stroke also vary from 3.62 by 3.7 inches in the XLD25 to 3.7 by 3.9 inches in the XLD28.


You can find Duramax XLD28 in:

  • 2012 to current Chevrolet Colorado
  • 2012 to current GMC Canyon
  • 2012 to current Chevrolet Express
  • 2012 to current GMC Savana vans

Common problems

Like XLD25 engines, the XLD28 have minor issues that may cause concern in terms of their durability and efficiency.

Is It Good Or Bad? Should I Buy It?

You should buy the XLD28 engines if you want a reliable and efficient engine for your Chevy or GMC vehicle.

Read more: TH350 vs. TH400 vs. 4L60E vs. 700R4

2014 – 2021 Duramax LWN

The Duramax LWN engines use the same 2.8L displacement as the XLD28 and have a similar inline configuration with four cylinders. The compression ratio is 16.5: 1 with a power output of 181 hp at 3400 rpm and 360 lb. ft torque at 2000 rpm.


Duramax LWN can be found in:

  • 2016 to current Chevrolet Colorado
  • 2016 to current GMC Canyon
  • 2017 to current Chevrolet Express 2500, 3500
  • 2017 to current GMC Savana 2500, 3500

Common problems

Like most current Duramax engines, the LWN are relatively new and haven’t been thoroughly tested to figure out their everyday issues. The only reported problems include DEF pump failures with the heater and turbo malfunctions. Apart from that, the engines are highly reliable.

Is It Good Or Bad? Should I Buy It?

LWN engines are good and a great buy in the current Duramax line-up. There are no major issues, and the typical issues are easily fixable.

2019 – 2021 Duramax LM2

Best Duramax Engine: What Are the Best & Worst Years? (11)

The Duramax LM2is the latest addition to the Duramax engine line-up with its 3.0L displacement and unique inline I-6 layout.


You may find Duramax LM2 in:

  • 2020 to current Chevrolet Silverado 1500
  • 2020 to current GMC Sierra 1500
  • 2021 to current Cadillac Escalade
  • 2021 to current Chevrolet Tahoe
  • 2021 to current Chevrolet Suburban
  • 2021 to current GMC Yukon

Common problems

Since it’s the newest Duramax model, the issues are not as common as you may detect in old models. The only problem you may find is weak tie rods, but it is unlikely most of the time. So far, the LM2 is considered the best 3L inline engine from DMAX.

Is It Good Or Bad? Should I Buy It?

You should buy the LM2 Duramax engine if you are in the market for a newly built 3L engine with DOHC, four valves per cylinder.

(Video) THE BEST DURAMAX EVER!? || LBZ Duramax


The extensive list mentioned above shows the best and the worst model years of the Duramax engines. You will get the most out of your money with the 2010 – 2017 Duramax LGH, 2011 – 2016 Duramax LML, 2011 – 2021 Duramax XLD25, 2012 – 2021 Duramax XLD28, 2014 – 2021 Duramax LWN, 2017 – 2021 Duramax L5P, and 2019 – 2021 Duramax LM2.

Engines before these are less reliable and plagued with major mechanical and structural issues and missing components. All in all, the latest Duramax engines are powerful and well-tuned to fit your GM and Chevy needs.

Read more: LS vs. LT vs. LTZ: What Do They Mean On A Chevy?


What are the best years of Duramax? ›

2006-2007 2500 & 3500. Perhaps the most desired of all Duramax models are the '06-'07 Classic body style trucks.

What's the most reliable Duramax? ›

LBZ: 2006 – 2007

It has the best potential for performance and horsepower additions through various Duramax parts mods and tuning. Built stronger and more durable than previous engines, the LBZ is reliable and powerful. The only weakness is that the pistons are known to crack if you get over 600 horsepower output.

What is the strongest Duramax engine? ›

L5P. The L5P duramax is the latest version of the Duramax V8 diesel engine. (engine code Y) Introduced in the 2017 model year it is the most powerful diesel pickup truck engine GM has produced with 445 hp (332 kW) at 2,800 rpm and 910 lb⋅ft (1,234 N⋅m) at 1,600 rpm.

What year Duramax has injector problems? ›

What year Duramax has injector problems? The LB7 Duramax built from 2001 – 2004.5 is known for injector failure. The good news is the replacement injectors you purchase from us incorporate several updates to help prevent repeat failures.

What year Duramax has the least problems? ›

L5P: 2017 To Present

The L5P is largely considered to be the best post-emissions Duramax engine. All the previous problems that plagued the injector pump and emissions system have largely been fixed. Mechanically, this engine is quite stout, and owners have reported very few problems.

What year Duramax gets the best mpg? ›

#1 – Chevrolet Silverado 2500HD
YearAverage Miles Per Gallon
201414.3 MPG
201614.3 MPG
201813.8 MPG
202013.1 MPG
6 more rows
Oct 25, 2021

Which is better Cummins or Duramax? ›

The Duramax leads with horsepower, but the Cummins is the king of torque with numbers up to 1,000 ft-lbs depending on the truck.

What's better LBZ or LB7? ›

The LB7 - stronger internals, injector issues, and 5 speed trans. The LLY - stronger internals, headgasket/overheating issues, but no injector issues, and 5 speed trans. The LBZ - weaker internals (pistons are weaker), but no injector/overheating/headgasket issues. Also get the 6 speed.

What is considered high mileage for a Duramax? ›

As for what's considered high mileage for specific diesel engines? According to Prosource Diesel, anything over 350,000-miles is considered high mileage for a used diesel pickup with a Cummins or Duramax engine under its hood. Anything over 350,000-miles is also regarded as high mileage for a Powerstroke diesel engine.

Is powerstroke better than Duramax? ›

Both the Ram's Cummins (seen above) and Ford's Power Stroke can pull over that amount, but the Duramax lags with a total towing capacity of 23,300. The Power Stroke wins here again with a total towing amount of 34,000 pounds versus Ram's 31,210 pounds.

What problems does the LML Duramax have? ›

The 4 Most Common Duramax LML Engine Problems
  • CP4.2 Injection Pump Failure.
  • DEF Heater Problems.
  • NOx Sensor Failure.
  • DEF Pump Failure.
Jan 9, 2021

Which is the best diesel engine? ›

What Are the 5 Best Diesel Truck Engines?
  1. Chrysler 3.0L EcoDiesel I-6. Diesel goes light-duty, but this small-but-mighty EcoDiesel is the industry's lone light-duty diesel engine: ...
  2. High Output 6.7L Cummins V8. ...
  3. Duramax 6.6L LBZ V8. ...
  4. Navistar/Ford 7.3L Power Stroke. ...
  5. Ford 6.7L Power Stroke V8.

Why is the LBZ Duramax so good? ›

The LBZ employed a thicker engine block casting, meatier connecting rods, and a higher pressure common-rail fuel system. This gave it more power and reliability versus any other Duramax to that point.

Which is better Cummins or Duramax? ›

The Duramax leads with horsepower, but the Cummins is the king of torque with numbers up to 1,000 ft-lbs depending on the truck.

Is the LML the best Duramax? ›

Beyond emissions systems and the injection pump, the LML is the strongest Duramax engine built to date.

How many miles should a Duramax last? ›

Overall, a properly cared for Duramax engine should last over 300,000 miles. However, consumers report having Duramax's lasting in the 500,000-mile range!


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