The 6.4L "Apache" Hemi is the more robust sibling of the 5.7. Most variants skip MDS entirely (especially the Ram 2500/3500 versions), so the lifter-collapse story that plagues the 5.7 mostly doesn't apply. The most common owner complaint is a normal valvetrain tick at idle. Here's the real reliability picture across SRT cars and HD trucks.
The 6.4 is one of the more reliable modern V8s when maintained. Most variants skip MDS so the famous Hemi tick is usually just normal lash, not a failing lifter. Watch oil cooler leaks and timing chain tensioner on high-mile cars.
The 6.4's solid lash adjusters and aggressive cam profile make a clearly audible tick at idle. On non-MDS variants this is simply how the engine runs and is not a sign of failure.
Run free diagnosis →Same valley-mounted cooler as the 5.7. Leaks show up as oil/coolant cross-contamination and can mimic a head gasket. Replace cooler and gaskets together.
Run free diagnosis →Newer Ram HD 6.4s use an electric primary coolant pump. When it fails, you get rapid overheating with no noise from the belt-driven side. Warranty replacement on most.
Run free diagnosis →Manifold studs break with heat cycles - a steady tick at cold start that fades as it warms is the giveaway. Common to broken bolt extraction and stainless-steel replacement.
Run free diagnosis →On 150,000+ mile cars the primary chain tensioner can rattle on cold startup. Replace tensioner, guides, and chain together.
View P0016 Diagnosis →Two plugs per cylinder means 16 plugs to change. Easy to skip - and Hemis run rough when they go too long. 30,000-50,000 miles is the right interval.
Run free diagnosis →Run a free AI diagnosis tailored to your exact vehicle. Get the most likely cause and repair estimate in under 30 seconds.
Run a Free Diagnosis on My 6.4L Hemi100% free · No signup needed · Powered by NHTSA + AI
No specific years to avoid. Pre-2014 cars without the updated oil cooler are slightly more prone to coolant-in-oil events, but the engine itself is sound.
2015-2020 SRT cars (Charger SRT 392, Challenger SRT 392, Scat Pack 392) and Ram 2500/3500 HD trucks all have strong long-term records. The HD truck variants skip MDS entirely.
Routine maintenance runs $500-$900/year - more in oil and plugs than a 5.7. Major repairs are infrequent but plan on $1,500-$3,000 for one larger event (cooler, manifolds, or tensioner) over 150,000 miles.
If your vehicle is throwing a check engine light, these are the codes most often associated with the problems above. Click any code for full diagnosis steps and typical repair costs.
Most variants do not. The Ram 2500/3500 HD versions are non-MDS. Some SRT cars use MDS but the failure rate is far lower than the 5.7. The 392 Scat Pack and most performance variants are non-MDS.
On non-MDS engines, no - it is a normal characteristic of the solid lash adjusters. A loud knock or a tick that gets worse with throttle is a different story.
With proper oil changes, 200,000-300,000 miles is realistic. The HD truck variants regularly hit 300,000+ in commercial service.
Generally yes - it skips MDS on most variants, has a stronger bottom end, and avoids the lifter-collapse failure mode that hits 5.7s.
Most variants spec 0W-40 full synthetic (Pennzoil Ultra Platinum or equivalent). The HD truck variants use 5W-40 in some applications - check your owner's manual.