The 2019 Chrysler 300 equipped with the 5.7L Hemi V8 may develop a characteristic ticking noise that's become known among enthusiasts as the "Hemi tick." Understanding this noise helps determine whether it's a benign characteristic or a symptom requiring repair.
The Hemi Tick Phenomenon
The Hemi tick describes various ticking sounds emanating from the 5.7L engine, particularly noticeable at idle or light throttle. This sound has become so commonly discussed among Mopar owners that it's earned its own name. The tick can originate from multiple sources, some concerning and others considered normal operating characteristics.
Exhaust Manifold Bolt Issues
A primary source of Hemi ticking is broken exhaust manifold bolts. The factory bolts are prone to snapping due to thermal cycling. When bolts break, the manifold no longer seals tightly against the cylinder head, allowing exhaust pulses to create a ticking sound. This noise often varies with engine temperature and may be more pronounced when cold.
Hydraulic Lifter Considerations
The Hemi's Multi-Displacement System (MDS) uses sophisticated hydraulic lifters that deactivate cylinders for fuel economy. These lifters can develop tick-inducing issues, particularly if oil changes are neglected. A sticking or failing MDS lifter produces ticking that follows engine RPM and may be specific to certain operating conditions.
Roller Rocker Arm Noise
The Hemi's roller rocker arms can develop wear points that create ticking sounds. Unlike traditional stamped rockers, roller rockers have bearings that can develop roughness. While less common than manifold bolt or lifter issues, rocker arm noise contributes to some Hemi tick cases.
Normal Versus Concerning Tick
Some Hemi ticking is considered acceptable by Chrysler and doesn't indicate impending failure. Light ticking that doesn't worsen, isn't accompanied by performance issues, and doesn't show on any diagnostics may simply be a characteristic of the engine. However, ticking that progressively worsens, correlates with power loss, or accompanies warning lights warrants investigation.
Diagnostic Approach
Technicians diagnose Hemi tick by isolating the sound source. Stethoscopes help pinpoint whether the noise originates from the top of the engine (lifters/rockers) or the sides (exhaust manifolds). Checking for exhaust leaks using propane enrichment or smoke testing confirms manifold bolt failure. Oil analysis can reveal lifter wear if metal content is elevated.
Repair Options
Exhaust manifold bolt repairs typically involve drilling out broken bolts and installing new manifold studs—a time-intensive but effective repair. Lifter replacement addresses MDS-related ticks but requires significant disassembly. Some owners opt to delete the MDS system, replacing the lifters with non-MDS components, which eliminates the complex deactivation hardware.