Failure mode - GM 6.0L V8 Gasoline (GM HD, LY6-L96 2008-2019; Express/Savana vans 2008-2020)

Valvetrain: lifter/rocker wear (no AFM on the HD 6.0)

Reliability tier: aggregated - verify before ordering, see /disclosure/

Symptoms

cold-start ticking that fades warm; a cylinder dropping contribution at mileage
traditional lifter/rocker wear - NOT the AFM lifter-collapse family (the HD 6.0 has no AFM/DFM; the half-ton 5.3/6.2 AFM reputation does not transfer here)

Compare with the other causes of the same sign on this engine: ticking, knocking, rattle or whine (4 causes) · misfire, rough idle, hesitation or surging (3 causes)

Root cause

Traditional lifter and rocker wear driven by oiling quality at high mileage; a single collapsed lifter drops one cylinder's contribution. The AFM lifter-collapse family does NOT apply - the HD 6.0 has no AFM/DFM hardware.

Diagnosis

locate the cylinder by stethoscope/tick timing before replacing parts
check oil pressure and filter condition - oiling drives lifter wear

Fixes

renew the failed lifter/rocker set; use the correct oil spec on refill - the dealer catalog does not surface HD-gas lifter PNs (catalog gap, disclosed) ()

gm-hd-gas-l96: valvetrain (honest catalog gap)

Prevalence

occasional