🔥 Best Duramax Engines Ranked (With Years to Avoid)
By Randy Worner • ASE Certified Technician • March 2024
If you’re shopping for a used diesel truck or van with a Duramax engine, one of the most critical questions is: which Duramax engines are the most reliable, and which should you avoid?
Introduced in 2001 through a partnership between GM and Isuzu (under “DMAX”), the Duramax turbo-diesel lineup includes a variety of 6.6L V8s and smaller inline diesels. Some are legendary for torque and longevity (like the L5P), while others (like the LB7 and LLY) are infamous for head gasket issues and injector problems.
📊 Duramax Engine Specs Comparison Table
| Engine | Horsepower | Torque |
|---|---|---|
| LB7 | 300 hp @ 3100 rpm | 520 lb-ft @ 1800 rpm |
| LLY | 300–310 hp | 520–605 lb-ft |
| LBZ | 360 hp | 650 lb-ft |
| LMM | 365 hp | 660 lb-ft |
| LML | 397 hp | 765 lb-ft |
| L5P | 445 hp | 910 lb-ft |
| L5D | 350 hp | 700 lb-ft |
| XLD28 | 200 hp | 360 lb-ft |
| LM2 | 277 hp | 460 lb-ft |
✅ Best Duramax Diesel Engines You Can Buy
- 2010–2017: Duramax LGH – Used in vans and chassis cabs
- 2011–2016: Duramax LML – First DEF/DPF era with better emissions design
- 2014–Present: LWN – Found in Colorado/Canyon; compact and efficient
- 2017–Present: Duramax L5P – Best-in-class power; great longevity
- 2019–Present: Duramax LM2 – Inline-6 diesel in Silverado 1500
- No major issues: XLD25 and XLD28 (Global market Diesels)
💡 Pro Tip: The L5P is widely regarded as the most refined and powerful Duramax yet — nearly 100% redesigned from earlier generations.
⚠️ Duramax Engines to Avoid
The following early-generation Duramax models suffer from major problems like cracked pistons, injector failures, overheating, and head gasket issues:
- 2001–2004: LB7 – Injector failures, no lift pump
- 2004–2005: LLY – Overheating, EGR problems, head gaskets
- 2006–2007: LBZ – Pre-emissions but still prone to piston cracking
- 2007–2010: LMM – Early DPF issues, crankshaft failure
Although the LBZ remains highly desired for performance, it may not match modern engines in reliability or emissions compliance.
🛠 All Duramax Engines: Applications & Common Issues (Full Table)
| Engine | Year Range | Vehicle Applications | Common Problems |
|---|---|---|---|
| LB7 | 2001–2004 | Silverado/Sierra 2500HD/3500HD, Kodiak/Topkick | Injector failure, overheating, head gaskets, limp mode |
| LLY | 2004–2005 | Silverado/Sierra HD, Hummer H1, Kodiak/TopKick | Turbo, lift pump lack, EGR, overheating |
| LBZ | 2006–2007 | Silverado/Sierra HD, Express/Savana vans | Cracked pistons, plug failure, water pump |
| LMM | 2007–2010 | Silverado/Sierra HD, Express/Savana | DPF issues, oil dilution, crankshaft problems |
| LML | 2011–2016 | Silverado/Sierra 2500/3500HD | DEF pump/heater, CP4.2 injection pump failure |
| L5P | 2017–Present | Silverado/Sierra 2500/3500HD | MAP sensors, injector #4 failure (rare) |
| L5D | 2019–Present | Silverado 4500/5500/6500HD, Intl. CV | Air filter clogging |
| LM2 | 2019–Present | Silverado 1500, Tahoe, Sierra, Suburban | Weak tie rods (rare) |
💡 Quick Verdict: Which Duramax Engine is the Best?
- 🔥 Top Overall: L5P (2017–Present) – 910 lb-ft torque, most power, most refined
- 🚚 Best for Vans/Chassis Cab: LGH (2010–2017)
- 🧰 Most Reliable Compact Diesel: LWN/XLD28
- 🆕 Best New Inline-6: LM2 (2019–Present)
📽 Recommended Video Resources
🚨 Should You Buy a Used Duramax Engine?
✅ Yes, if:
- You’re buying 2011+ models with DEF/DPF systems (LML, L5P, LM2)
- You need a reliable workhorse with high torque
⚠️ Avoid, if:
- You’re considering 2001–2006 models without upgrades
- Previous owner has deleted emissions systems
📚 Read More:
- LB7 vs LBZ vs LML vs L5P: Which Is Best?
- Best Camshafts for 6.6 Duramax Diesels
- Gas vs. Diesel Trucks for Towing
Written by Randy Worner – 45 years experience, ASE Certified Instructor, Chevy Geek founder
