GMC Sierra 1500 K2XX

4.3L V6, iron block, direct injection only — GM's quiet workhorse. AFM deactivates 2 of 6 cylinders, same lifter design as the V8 but statistically far less failure-prone. Valves coke from 80k miles without port injection. Pulls 285 hp, enough for an empty bed, not enough for a loaded trailer on a grade. Runs 250k+ miles with 5,000-mile oil changes.

• !! Timing Chain Wear from 160,000 km

  Cold start rattle from chain tensioner/guide wear.

  Symptoms: Cold start rattle, P0008/P0016 codes
  800–1,800 $
  Ad 12632728 GM timing chain tensioner LV3 4.312686368 GM timing chain guide LV3 4.3
• !! AFM Lifter Tick from 120,000 km

  Cylinder deactivation wears lifters — same issue as 5.3L, but less frequent.

  Symptoms: Ticking/knocking, misfires, check engine light
  1,500–4,000 $
  Ad 12645725 GM AFM valve lifter LV3 4.312499225 non-AFM lifter LV3
• !! High-pressure fuel pump (HPFP) failure from 100,000 km

  High-pressure fuel pump can fail — bad fuel or clogged filters accelerate wear.

  Symptoms: Hard cold start, stalling, power loss, engine hesitation
  600–1,500 $
  Ad high pressure fuel pump 4.3 LV3HPFP LV3 EcoTec3 12668040

+ 1 more engine weaknesses + vehicle weaknesses

5.3L V8, iron block, the most-produced truck engine in North America. DFM shuts down up to 15 of 16 firing patterns — and that's the problem. Lifter needle bearings starve for oil in deactivated cylinders, skid across cam lobes, send metal through the engine. Two class actions pending. A $200 Range disabler buys time; a $2,500 mechanical delete with DOD-delete cam is the permanent fix. Run 0W-20 Dexos, change at 5,000 miles maximum.

• !! AFM/DFM Lifter Failure — Class Action from 100,000 km

  THE GM truck problem: deactivated cylinder lifters wear from oil starvation. Needle bearing skids on cam lobe, metal debris in oil. Two class actions pending. $3,500-8,500 repair. AFM/DFM delete kit as permanent fix.

  Symptoms: Loud ticking/knocking, misfires, rough running, check engine, sometimes from just 25k miles
  3,500–8,500 $
  Ad 12698946 AFM lifter valve assembly L8412645725 AFM lifter GM 5.3L12723516 DFM camshaft repair kit L84DFM lifter delete kit 5.3 EcoTec3
• !! Oil Consumption — Piston Rings (Class Action) from 80,000 km

  Separate class action: $150M settlement for 2011-2021. Piston rings let oil pass — 1 quart per 2,000 miles in severe cases.

  Symptoms: Blue smoke, dropping oil level, fouled spark plugs
  2,000–6,000 $
  Ad 12698946 AFM lifter L84 5.3LHastings 2M5380 piston ring set Gen V 5.3L
• !! Timing Chain Wear from 160,000 km

  Same issue as LV3 — chain and guides from ~100k miles.

  Symptoms: Cold start rattle, P0008/P0016
  1,000–2,500 $
  Ad 12630107 timing chain tensioner Gen V LT12680750 timing chain kit 5.3L EcoTec312713934 crankshaft sprocket gear Gen V

6.2L V8, 420 hp, same Gen V architecture as the 5.3 but deeper exhaust note and noticeably more shove. 2021-2024: manufacturing left metal shavings in 597,000 engines — GM's fix was switching to 0W-40 oil. NHTSA opened an investigation into post-recall failures. Same DFM lifter risk as the 5.3. Pre-2021 or confirmed post-recall units with documented oil changes are the buy.

• !! Recall: Metal Shavings in Engine — 597,000 Vehicles

  Manufacturing debris (metal shavings) in engine destroys bearings. 2021-2024 L87. Free engine replacement, 6-8 week wait. NHTSA investigating post-recall failures.

  0–0 $
  Ad L87 engine recall 25V274 replacement engineGM safety recall N252494001 L87
• !! AFM/DFM Lifter Failure from 100,000 km

  Same lifter issue as 5.3L — cylinder deactivation wears lifters.

  Symptoms: Ticking/knocking, misfires, rough running
  3,500–8,500 $
  Ad 12688943 GM MLS head gasket 6.2 L87L87 DFM delete kit 6.2 Gen V
• !! Oil Consumption — Piston Rings (2019-2020 and older L87) from 80,000 km

  Piston rings let oil past — 0.5-1 quart per 2,000 miles in severe cases. Also affects 2019-2020 L87 not covered by the machining debris recall. NHTSA investigating these cases separately.

  Symptoms: Blue smoke, dropping oil level, fouled spark plugs, positive oil consumption test
  2,500–7,000 $
  Ad piston rings GM 5.3 L84oil consumption fix Silverado

+ 1 more engine weaknesses + vehicle weaknesses