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A second, later Pentastar 3.6 failure mode is valvetrain wear: a rocker-arm roller wears, loosens and drops, throwing the rocker off the cam and producing a ticking or tapping that can escalate to a misfire or internal damage if driven on. 161 federal ENGINE complaints on the 2014-2019 3.6 models (Wrangler, Grand Cherokee, the vans, Charger and 300) name rocker arms or lifters. Owners report dealer rocker/lifter replacements and PCM reflashes, with the noise often appearing at highway mileage rather than when new.

Check — Listen for a persistent tick or tap that does not clear after an oil change and is not just cold-start injector noise; ask about any rocker-arm, lifter or valvetrain work and any PCM/ECM reflash. A tick left unaddressed can score the camshaft and turn a rocker job into an engine job.