The Lemon Index
The 6.6 L V8 turbo diesel in the Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD, model years 2007–2010. Owners filed 385 complaints about trucks with it (matched by VIN); 8% name the engine, #9 of the 12 diesel truck engine generations we track (1 = the most).
Known issues, checked against owner complaints
None of the issues people usually talk about stands out in this engine's complaints to NHTSA.
Also often talked about, but not standing out in complaints to NHTSA: the DPF / regen system (1 of 385, 0.3%, peers 0.1%). That doesn't mean it never happens, only that owners rarely file it with the government.
What YouTube owners say Tone 0-100, higher = more praise than trouble.
Average owner tone 41/100 across 4 model years, from 106 videos about this engine and its cars.
Most-watched videos
- Duramax LB7, LLY, LBZ, LMM, LML, L5P Explained! 378,938 views
- Why I Downgraded to a LBZ Duramax from a LMM? 291,723 views
- Duramax LBZ & LMM - WHAT'S THE DIFFERENCE? by Duramaxtuner.COM 183,949 views
Counted from video titles and captions: praise words against trouble words, weighted by views. Videos only count when the title names this engine or a car that had only this engine in those years.
Owner complaints by model year
Counts of complaints filed so far. Older trucks have had longer to collect them, and popular years draw more because more were sold: no one reports sales by engine, so there's no per-truck rate. Compare the shares below instead.
What owners complain about
Share of this engine's complaints that name each area (one complaint can name several).
What owners write
| Complaints that | Count | Share | Median, other diesel truck engines |
|---|---|---|---|
| Say the engine stalled, shut off or lost power | 20 | 5.2% | 7.8% |
Counted from the owner's own words in each complaint (all of the truck, not only the engine). A share, not a failure rate.
When problems show up
Half of the owners who gave a mileage reported the problem between 28,517 and 102,000 miles; the middle report was at 60,000 miles (212 complaints with a mileage).
Recalls that name this engine 0
No NHTSA recall on these trucks names this engine.
NHTSA recalls on these trucks and years whose text names this engine (its size, or diesel / Cummins / Duramax / Power Stroke). The rest (brakes, air bags, wiring ...) are on each truck year's page.
Trucks with this engine
In owners' words
I keep going back to get the recall done and they keep telling me they don't have parts .This has gone on for years
2009 Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD owner · NHTSA complaint 11746826
Local dealer is not repairing my recall. I keep getting told parts are not available and this has gone on for years.
2009 Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD owner · NHTSA complaint 11678524
The contact owns a 2007 GMC Sierra 3500. The contact received notification of NHTSA Campaign Number: 15V324000 (Air Bags) and would like to be removed from the recall distribution list. The local dealer and manufacturer were not contacted.
2007 Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD owner · NHTSA complaint 11671977
Against the other diesel truck engine generations
| Engine | Years | Complaints | Name the engine | Name the fuel system | Stalled or lost power | Recalls naming it |
|---|---|---|---|---|---|---|
| 6.0 Power Stroke | 2003–07 | 1,708 | 34% | 16% | 31% | 2 |
| 6.4 Power Stroke | 2008–10 | 572 | 28% | 7% | 11% | 2 |
| Duramax L5P | 2017–26 | 1,229 | 16% | 10% | 14% | 2 |
| 7.3 Power Stroke | 1999–03 | 2,049 | 15% | 5% | 12% | 1 |
| Duramax LML | 2011–16 | 779 | 13% | 20% | 17% | 0 |
| 6.7 Cummins | 2007–26 | 7,667 | 11% | 8% | 6.4% | 9 |
| 6.7 Power Stroke | 2011–26 | 5,640 | 10% | 11% | 7.8% | 6 |
| Duramax LBZ | 2006–07 | 186 | 8% | 5% | 7.0% | 0 |
| Duramax LMM | 2007–10 | 385 | 8% | 6% | 5.2% | 0 |
| Duramax LB7 | 2001–04 | 592 | 7% | 17% | 5.4% | 1 |
| Duramax LLY | 2004–06 | 374 | 7% | 11% | 7.8% | 0 |
| 5.9 Cummins | 1999–07 | 3,245 | 4% | 7% | 5.0% | 0 |
Shares of each engine's own complaints, matched by VIN. They show what owners complain about, not how often trucks break. Every diesel truck engine compared
Quick answers
Is the Duramax LMM reliable?
No one reports sales by engine, so there's no per-truck score. Of the 385 complaints owners filed about trucks with it, 8% name the engine, #9 of 12 diesel truck engine generations we track (1 = the most).
What trucks have the Duramax LMM?
In our data: the Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD, model years 2007–2010, matched by the VIN in each owner complaint.
What are the most common Duramax LMM problems?
In owner complaints to the government: airbags, electrical, engine.
How many recalls name the Duramax LMM?
0 NHTSA recalls on these trucks name it.
Source: NHTSA owner complaints (FLAT_CMPL + COMPLAINTS_RECEIVED_2025-2026), received through 20261109; engines: NHTSA vPIC VIN decoder; NHTSA recalls API. Engine names and years: GM (RPO codes).