6.4 Hemi (Max Miles, Problems & Towing)

If you’d like to know what the maximum mileage is you can get from a stock 6.4 Hemi, then you’ve come to the right place. We’ll also discuss what problems these engines commonly experience, as well as if it’s a good towing truck.

The maximum mileage you can expect from a 6.4 V8 Hemi is anything in excess of 250 000 miles.

So if you are looking at buying a used 6.4 Hemi with some mileage on it, what are some of the potential issues you need to be aware of? Are these engines reliable enough to buy used, and what do some owners have to say about ownership. All these questions and more will be covered in this article.

Just a quick online search will show you how happy most 6.4 Hemi owners are and the kind of mileage these engines can rack up with ease. Reliable high mileage on these engines are becoming the norm it seems.

Still don’t believe me?

Let’s have a quick look at some real world feedback from the Hemi 6.4 owners themselves. Most of these Hemi’s don’t have easy lives.

Owners Feedback

This is by far the best Ram truck I’ve owned. Even after 127k miles, close to 100k miles towing the truck still feels/rides like a new one. I can’t say the same about the previous generations I’ve owned. I can see myself owning this truck beyond 250k easily.

https://www.ramforum.com/threads/how-many-miles-on-you-6-4-hemi.100126/

2015 6.4 CC 21,000 miles. No major issues. One recent episode of the transfer case hanging up when trying to get out of 4wd. occasional rough shift 4 to 5th gear. some heat shield rattling likely my fault from getting my truck stuck in axle-deep mud. my 8.4 radio won’t keep the correct time. Otherwise, just plain joy to drive. More than any other truck I’ve owned.

https://www.ramforum.com/threads/how-many-miles-on-you-6-4-hemi.100126/

There you have it, straight from the owner’s mouths.

Let’s take a quick look at what makes these 6.4 Hemi engines so darn durable.

6.4 Hemi Specifications

max miles 6.4 Hemi Last
max miles 6.4 Hemi Last

There are two “versions” of the 6.4 Hemi engine. The one build or tweaked for the trucks and the other for the cars. In 2014 the Truck engine was developed for the Ram Trucks in a 6.4 v8 displacement hemispherical combustion chamber design with a domed cylinder head. Hence the name “Hemi”

The 6.4 “truck” version of the Hemi produced ponies between 367BHP and 410BHP with peak torque maxing out at 429 lb-ft @ 4,000 RPM for both the pickup and chassis cab models.  

So what makes this Hemi so durable?

See, the smart engineers learnt from their past mistakes and basically redesigned this engine from the ground up to be durable, economical and reliable while hauling and towing. 

They accomplished this by modifying the exhaust valves by replacing them with sodium-filled exhaust valves.

What does that accomplish you ask?
 
Well, we all know a cooler combustion chamber is a happier, more efficient combustion chamber. So, when V8 Hemi engine warms up, the sodium inside the valve melts and basically transfers the heat from the valve head up the valve stem and into the valve guide, away from the combustion chamber.

Watch this video for a better explanation. FFW to 1.53sec for the sodium filled valves part.

OK, what else did the white coats improve on the 6.4 Hemi to make it so reliable?

They used some high-tech aircraft-grade stainless steel exhaust gaskets and fasteners. They also incorporated oil jets for cooling the pistons. They also installed a high-volume oil cooler and improved the cooling system by using computational fluid dynamics

What is Computational Fluid Dynamics or CFD I hear you ask?

Basically, the white coats use clever computer dynamics to analyze and solve problems that involves the way fluid flows.  

So they really did a number on these V8’s and it makes a massive difference in terms of the vehicles durability and long-term reliability.

So is this beautiful masterpiece problem free?

Let’s find out!

Potential 6.4 Issues

  • Gas engine struggles with towing up steep hills
  • Poor gas mileage while towing
  • High transmission temps climbing steep hills/towing

In an attempt to protect the Hemi engine, when towing a heavy load up a steep incline for extended periods, the engine will govern you to 35mph to prevent over-revving.

Many owners have complained about sluggish performance and poor gas mileage when towing heavy loads with the Ram, only returning as low as 6MPG. This is weird since the 6.4 torque curve is about 1000rpm lower than the 5.7 which means it gains power earlier in the rev range allowing you more control and power when towing. 

How Many Miles Will A 6.4 Hemi Last (Life Expectancy)

A Hemi is a heavy-duty, durable, reliable engine which, when not towing heavy loads, returns decent gas mileage for the size of the truck. It also has the cool MDS (Multi Displacement System) engineering built in, which means, when driving around town or on the highway it will shut down 4 cylinders and not use all 8 cylinders, for better fuel economy.

These engines are built really robust, yet intelligent. They are actually quite overbuilt and endure rigorous testing for longevity. These engines are built to last so as the years roll on, you should see more and more Hemi’s with 300K miles running around.

Ram 6.4 Hemi Problems

  • MDS solenoid fail.
    Many earlier model owners reported this issue, resulting in the engine running rough.
  • Wrist Pin Issue
    Early 6.4 V8’s suffered from the Wrist Pin Issue. This was evident on the 2014 models where the engine would emit a loud ticking or knocking sound after it sat overnight. The cold-start would give off a loud knocking noise after an overnight cold soak. Certain engines built in 2014 where built with the incorrect piston wrist pins, resulting in a 30 minute long audible knocking noise.

For more information, download the service bulletin here: 2014 Ram 6.4 Hemi Service bulletin (Knocking noise)

Although the service bulletin only covers the 2014 year model, does not mean Dodge is not liable to replace your engine if your model is not within the date range and showing the wrist pin ticking/knocking symptoms on cold start.

  • Vibrations from the engine. (Possibly caused by the MDS Solenoid failing and rough running)
  • 6-Speed Transmission
    Dramatic Downshift from 2nd Gear to 1st Gear when hauling or towing heavy loads up steep hills.

How Many Quarts of Oil Hemi 6.4

2014 SpecsTruck 5.76.4 Truck
Compression10.5:110.0:1
Max revs5,800 rpm5,800 rpm / 4,660 with Aisin
Oil capacity7.0 quarts7.0 quarts (6.62 liters)
Coolant18 quarts15.75 quarts (15 liters)

Does 6.4 Hemi Need Premium Gas?

According to the owner’s manual, 89 is recommended, 87 is acceptable. Premium offers no added benefit.

Is The 6.4 Hemi Good For Towing?

Watch this video and decide for yourself:

Wow! It started off so well

Resources

2014 6.4 V8 Service Bulletin

Hemi 2014-18 Air Filter Intake Kit

Hemi 6.4 Catch Can Kit

Genuine Mopar Oil Filter

Hemi 6.4 Lifters Set w/MDS

Full Synthetic Motor Oil

Jeep Hemi 5.7/6.1/6.4 Racing Thermostat, MMTS-JED-06L

https://www.ramforumz.com/threads/how-long-does-the-hemi-last.200097/

https://www.ramforum.com/threads/how-many-miles-on-you-6-4-hemi.100126/page-3

Conclusion

There is no reason that most modern engines can’t easily make it to 300k with proper preventive maintenance. The 6.4 Gas Hemi is a brilliant engine, however, it has a few shortcomings. If you want to tow then rather opt for the 8-speed transmission since it manages the power better than the 6-speed. 2014 models were recalled due to the incorrect piston wrist issue. Overall still a great package and offers a good mixture of power and economy.

Jade C.

4-Wheel drives and off-road driving techniques has been my passion for over 20 years. Here we strive to provide the most accurate, up-to-date, information about the functionality, common faults and latest technology built into most 4 Wheel Drives.

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