How Long Does A Diesel Engine Last?

Diesel engines last a long time! The engine will likely outlast every other part of your vehicle. The problem a lot of time is the body doesn’t hold up. I had an old Volvo transfer truck that was falling apart. The shifter was so loose you could not tell where the gears were. The dash was so worn out nothing worked! The headliner was falling, seats were trash but she rolled on.

How long does a diesel engine last?

On average a diesel engine will last 865,000 miles or 34,650 engine hours before needing a major overhaul. Most diesel engines have a major failure between 700,000 and 1,000,000 miles and will require an overhaul.

A benefit to diesel engines is after an overhaul they will last many more miles. The numbers I’m giving are until the first rebuild of the engine. I’ve seen engines with over 2,000,000 miles on them and have been rebuilt three times.

I’m certain that a perfectly maintained and rebuilt periodically diesel engine will last a lifetime. In this article, I want to take a look at why diesel engines last so long. We will then talk about the cost of rebuilding and overhauling a diesel engine. And lastly, we will see how to get the most out of a diesel engine. Let’s get to it.

Why do diesel engines last so long?

Diesel engines last longer because they run at a lower RPM, have larger internal parts, have a better lubrication system, and are gear-driven.

Diesels run at a comparatively low RPM rate to other engine types. Diesel engines idle around 750 RPM. A diesel will average around 1000- 1500 RPM running down the road. A gasoline engine will have twice that and a two-cycle twice of a gas engine.

Running at a lesser RPM creates less heat and therefore less wear on the components. Overall, it’s like having a slower heartbeat. Creates longer life for the components in the engine itself.

The large internal parts of diesel engines make for long-lasting life. The sheer size of the crank and cam will let you know that they are not even close to a gas engine.

With the larger components, comes the larger need for oil. Diesel engines have huge supplies of lubricating oil. My Cummins ISL takes 10 gallons. With all that oil, a diesel engine stays pretty well cool and lubricated. This helps with wear time for sure. Components stay cooler when they are lubricated.

Diesel engines being gear-driven make the likelihood of breakdown a lot less. With no belts or chains, the diesel engine is a more secure timing system. The accessories are often gear-driven as well. Remember also that, unlike gasoline engines, diesels have no ignition system, just a fuel pump. This is a lot fewer parts to break and cause problems.

Need to know when to call it quits on your engine? See my article on signs of a worn diesel engine.

How much does an overhaul on a diesel engine cost?

After a survey of 6 shops around the USA. The average cost of a diesel engine overhaul is 9400 dollars. This cost will vary on the size and manufacturer of the diesel engine. This cost was as low as $6,400 and as high as $16,800.

This gives you an idea of the significant investment an overhaul is. Below is a table of the average cost per manufacture of an engine type

ManufactureEngine Average Cost
Power Stroke7.3L$8,300
Duramax6.6L L5P$7,900
Detroit 60 Series$16,800

How to get the most out of my diesel?

You can get the most out of your diesel by doing routine maintenance on time, sending off oil samples, doing your daily inspections, and operating the unit correctly.

You may times see in diesel engines the maintenance intervals being ignored. Doing regular maintenance on time, every time is going to aid the life of your diesel engine. If the maintenance is not kept on a regular schedule you open yourself up to major failures early on.

Keeping things greased and oil being kept in good condition is going to bring your diesel the most benefits over time. As a part of keeping those oils changed and inspected you’re also going to catch things that are not right early on before they become big problems.

Something you can do (that people often don’t) is take an oil sample. Oil samples are very valuable and very cheap when in comparison to an engine overhaul. There are many times that we caught coolant in the oil or other variables early on and avoided major failure and breakdown.

A daily inspection is another avenue that you can catch things early on. A good visual inspection of your engine area every day is going to aid you in seeing things when they’re off. A hose being loose or detecting a leak early on will prevent major failures.

Last but not least, operate your diesel engine correctly. Many times we see abusive operations in different applications. I worked in a fire fleet shop and we would often see different types of failure because of the nature of this application. They have the pedal to the metal everywhere they go.

understanding your specific application and how the engines can be abused can make a big difference in avoiding these behaviors and getting the most life out of your engine.

Summing up

We all have stories of trucks that lived long past their interior. Everything in the truck is falling apart and they are still chugging along. The diesel engine is a modern marvel not to be overlooked! It will continue on into the future for many years to come.

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