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Symptoms · Duramax LML (2011-2016)

Duramax LML (2011-2016): ticking, knocking, rattle or whine

2 documented failures on this engine list this among their signs. They are ordered from the most widespread down. Each one shows the signs in its record's own words, how to tell it from the others, the usual fix and any recall or bulletin.

1. VGT turbo vane carbon / actuator wear (Garrett VVT) Common
2. Cooling system wear: water pump, fan clutch, oil cooler (LML) Occasional

Not sure which engine you have, or want the recalls for your exact truck? Check your VIN: it names the engine and lists the campaigns for that model year. Whether a recall is still open on your VIN: nhtsa.gov/recalls.

1 VGT turbo vane carbon / actuator wear (Garrett VVT)

aggregated How widespread: Common

How it shows up

• underboost codes (P0299), limp mode under load, whistling/whoosh changes

Its other signs

• gradual power loss traced to stuck VGT vanes (carbon) or a worn actuator

How to tell it apart

• command the vane actuator through its travel with a bidirectional tool
• rule out boost leaks (charge-air pipes, clamps) before condemning the turbo

Usual fix

turbo service by diagnosis: actuator/VGT-vane service, charge-air leak repair, or turbo assembly replacement

Root cause, parts and sources →

2 Cooling system wear: water pump, fan clutch, oil cooler (LML)

aggregated How widespread: Occasional

How it shows up

• coolant seepage at the water pump weep hole; bearing growl

Its other signs

• overheating under tow traced to a locked/loose fan clutch
• oil-cooler service themes carried over from the earlier Duramax era

How to tell it apart

• pressure-test the system; verify thermostat and fan clutch operation under load before radiator replacement
• inspect the oil-cooler lines at service intervals

Usual fix

replace the failed cooling component; use the correct coolant spec on refill

Root cause, parts and sources →

Other symptoms on the Duramax LML (2011-2016)

Hard start, long crank or no-startLoss of power, limp mode or derateLosing coolantMisfire, rough idle, hesitation or surgingDEF, DPF and regeneration warnings

Everything on the Duramax LML (2011-2016)Its recalls and bulletins

Order: how widespread each failure is in its record (near-universal, very common, common, occasional, rare), then the number of NHTSA owner complaints that match its keywords. Complaint counts are keyword matches, not a manual review of each complaint. A symptom listed here means the failure is documented with that sign; it is not a diagnosis of your truck. Tiers: verified, aggregated, contested, data-gap. How we tier and source facts.