How Long Will a 5.9 Magnum Last? And What Are Its Common Issues?

The first 5.9 Magnum engine appeared in 1992. Today, these engines are not really up-to-date, but they are interesting as the base blocks for upgrades and improvements by car enthusiasts. Also, some original cars and trucks equipped with this Magnum engine are still on the go and ready to drive almost anywhere.

On average, the 5.9 Magnum engine can go about 280,000 miles. But there are units that hit the 400,000-mile mark as well as those that barely reach 200K miles. Of course, the durability is not a stable figure and it may change according to maintenance, type of use, and overall care about the engine.

Key features and my opinion about the engine

• Production years:1992-2003
• Average lifespan of 5.9 Magnum:250,000-280,000 miles
• Fuel supply type:port injection
• Power range:230-250 hp
• Fuel efficiency:awful
• Engine block material:cast iron
• Engine reliability score:high
• The most common problems:very high octane number demand, lifters need high-quality oil, engine mounts aren't long-lasting, minor issues are pretty common.

What should you know about the 5.9 Magnum engine?

This is the legendary V8 engine codenamed EML. It was made by Chrysler between 1992 and 2003. The engine was installed in Dodge Ram, Dakota, Durango, Ramcharger, and also in the Jeep Grand Cherokee (just for two years in 1997 and 1998). This is the marvelous engine that represents the best era of American ICE technologies.

Yes, this was the time when manufacturers didn't care much about fuel consumption and only thought about durability and power. The 8-cylinder EML engine is one of the best representations of that part of American car history. But still, it comes with its share of flaws.

Here are some facts about the 5.9L engine you should know:

• this is the V8 5.9-liter all-iron engine which means both block and head are made of cast iron, no aluminum here;
• the engine may develop 230-250 horsepower in stock and three times more if upgraded to its full potential;
• it also develops up to 347 lb-ft in its stock condition which is astonishingly good for trucks and big SUVs;
• surprisingly, the engine has hydraulic lifters, so no need to worry about valve adjustment;
• the fuel supply system is simple and reliable - just port injectors that are easy to maintain or replace;
• also, the engine doesn't have any turbocharger, there are no phasers, the timing system is driven by the chain - everything is reliable and very simple;
• the surprising fact is that when in stock this engine can offer about 10.5 MPG in the city which is not really economical.

Well, what would you expect from a V8 engine with almost 6 liters of displacement? It drinks fuel like crazy. Even though the fuel supply system is pretty simple, it still requires high-quality fuel which is unusual for that generation of engines. The unit will show its optimal power and torque only with high-octane fuel.

Overall, this engine has a wonderful profile of good reviews including professional opinions. But today, it's not really usable because of poor gas mileage and questionable emission features. In the era of EVs and hybrids talking seriously about the engine that shows 10 MPG during careful city driving is ridiculous. So, we perceive this machine purely as a unit for upgrades and sports.

How many miles will the 5.9 Magnum go?

The 5.9 Magnum is a really reliable and great engine but it's impossible to say for sure how many miles it will last. I can only think of average life expectancy. And it should be about 280,000 miles.

It doesn't mean that with good maintenance and careful use, these engines can't make it to 400K miles. After a good repair with new rings and valve seals, they will most likely go another 100-200K miles. But for this, you will need to maintain the engine as if it's the only car you'll ever get in your life and you need to drive it whatever happens.

The 5.9 Magnum has several problems that may prevent it from going over 300,000 miles. First of all, its repair and overhauling will cost you a fortune because it's not that easy to get proper parts and the labor is now insanely expensive. Secondly, there are some common issues that make the life expectancy of the engine shorter.

What are the common problems with the 5.9 Magnum?

Unfortunately, this engine has several serious problems that you may find concerning. Before you buy one for upgrades or just in a used truck, you should make sure you understand these issues and know when they may happen. Also, buying any 5.9 Magnum engine with more than 200K miles on it is not a very good idea unless you only need the block for a total engine rebuild.

Here are some issues that you may want to know about:

1. This engine is surprisingly demanding in terms of fuel

The quality and octane number of the fuel that you fill in the tank of the car equipped with this engine are super important. If you are going to buy cheaper gas from no-name gas stations located in the middle of nowhere, you maybe should avoid buying this engine. The fuel supply system and the emission system will most likely say goodbye to you much earlier than you expect.

In return, you will be saying goodbye to a lot of your money to repair the engine. Yes, it's pretty simple in its construction, but no one said it was cheap to repair.

2. Head issues

The head in these engines is cast iron which is unusual. The majority of engines have aluminum head and this can be explained by the resistance of aluminum to heat cracking. If you overheat the engine or use very poor-quality fuel, it may be that the head will just crack between the valves. Any misfiring, vibration, and other unpleasant issues with this engine also may lead to cracking of the head.

I should tell you that the repair in this case will cost you a fortune. Finding a good used head for this engine is not the easiest task you can think about. The new one is priced like an airplane wing or something.

3. Hydraulic lifters may get stuck

Usually, this happens in engines that don't get proper maintenance. And it's important to know if you are going to buy the used EML engine. The 5.9 Magnum needs proper oil change intervals. Otherwise, the hydraulic lifters may stop working. They literally get stuck and stop pushing valves to their proper places. This leads to misfiring problems and eventually can also lead to head cracking.

Also, this may happen when you don't use the proper oil type and viscosity. Lifters are pretty tender here and need only clean and proper oil to function well.

4. Engine mounts go bad pretty often

The engine weighs over 500 pounds, so the mounts don't have an easy life, you know. It leads to one of the mounts committing suicide once in a while. Unfortunately, the price for parts is not that low. And also the labor is going to cost you some money. This is not a crappy light three-cylinder engine that the mechanic can lift with one hand. You need some equipment to change the engine mount in this machine.

5. The water pump is not that reliable

While there are some other parts that can fail, they are not as important as the water pump. If this thing fails, you will witness fast heating of the engine. But what if you don't look at the gauge and don't notice that the engine is overheating? Well, then you may need to read the part where I describe engine head cracking in the 5.9 Magnum.

The water pump is not eternal and should be replaced at least after each 80-90 thousand miles. Also, this is a great time to check the timing chain.

Can you prolong the life of the 5.9 Magnum?

Yes, you can. For this, you should maintain this engine as if it's the most precious thing you have. Seriously, maintenance is the king when it comes to big V8 Chrysler engines. One mistake with fuel quality or oil type can lead to fatal issues.

So, here's what you should know about this engine:

• the V8 EML engine wants 5w30 oil and a new filter at least once a year or once every 10K miles;
• you don't want this engine to make weird sounds - if this happened, just go to a good mechanic and have the machine inspected;
• avoid racing at 4000+ RPM for a long time - this engine wasn't originally made for high revs;
• look at that engine temperature gauge and avoid driving the vehicle if that gauge is showing something really weird;
• buy only good fuel and watch the MPG - it shouldn't go too far from average, this may also mean that some problems started developing.

It's not that hard to make your 5.9 Magnum live longer than average. Just make sure the engine is getting proper care and never ignore any problems like vibrations or unusual sounds. Also, avoid aggressive driving unless your Magnum is prepared for this and has gone through several stages of professional upgrades.