How Long Do Diesel Generators Last?

Generators are an important part of a company’s power system, particularly those companies in the industrial sector. Among many other benefits, businesses choose diesel engine generators because they are reliable and have a long life expectancy, which matters because that is a key factor into a company’s short- and long-term budget.

For your business, you need a generator that works at any given time. We live in a volatile environment today, whether it’s the economy, the climate or politics. Any one of these things can cause interruptions in business and in the power that supports your business. When interruptions occur, you need a generator that is dependable and that will endure the test of time.


Do Diesel Generators Last Longer Than Natural Gas Generators?

Both diesel and natural gas generators each have their benefits. Diesel has traditionally been the go-to choice, mostly because there are fewer equipment suppliers with the required expertise to provide, transport, set up and maintain natural gas generator sets. Selecting the right generator is also dependent upon numerous other factors such as fuel supply and storage, operating conditions and load requirements. Diesel powered generators do have an edge when it comes to longevity (measured in usage hours).

Part of the reason for this longevity is in the way it is made and what it is made with. Diesel engines are made of simpler and slower moving parts, so the mechanical pieces do not rub together as they do with natural gas generators. As such, diesel generators may not wear out as soon.

A diesel engine-powered generator is reliable, powerful and has a long life span. These things matter because having energy when you need it matters. But how long do diesel generators last? The answer is: it depends. The following is an explanation, including the factors that determine the diesel generator lifespan.


The Approximate Answer

There is no one answer to this question. But there are a lot of approximations. Considering that diesel powered generators are cooled by water and mostly run at 1800 RPM, they typically last longer than the standard generator, which is cooled by air and runs on 3600 RPM. Diesel powered generators can go at a minimum of 12,000 hours and upwards to 20,000 hours before they require engine overhauls — so long as they are exercised and well-maintained. That’s a pretty good range. And at 4 hours a day, it will take 14 years before you reach 20,000 hours. That’s nearly 1.5 decades of service to you and your business before major engine or generator servicing is required.

But again, these are all approximations. To better understand the length of time your diesel engine generator will last, you need a more accurate answer that takes into consideration several other factors.


The Accurate Answer – It Depends

An accurate answer to the question of a diesel engine’s life expectancy can only be determined by considering several important factors: (1) maintenance; and (2) generator sizing.

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Any kind of equipment requires maintenance in order to keep it in good running condition. That is no different when it comes to diesel generators. If you want your generator to last upwards of 50,000 hours before a major overhaul is required, then you need to maintain your generator in good running order. This means: (1) the parts of the engine must receive regular maintenance; and (2) the generator must regularly be exercised.

Regular maintenance includes things like regular oil changes or air and fuel filter changes. It also means checking for any kind of change in performance, which could be indicated by any of the following signs:

  • Sound
  • Vibration
  • Smoke
  • Increase in fuel consumption

Any of these signs can indicate that the generator needs servicing. But to be able to identify these signs, you must regularly be exercising the generator.

The importance of exercising the generator regularly cannot be overstated. It is fundamental to maintaining the lifespan of your equipment. If a generator does not receive adequate exercise, the machine, when used , can go from cold to hot rather quickly and place unnecessary stress on the engine parts. This stress – like the friction caused by other gas engine generators – can shorten the life of your generator. To prevent this cold-to-hot process, ensure that you regularly exercise your generator. Regular use of the generator benefits the equipment in the following ways:

  • Engine parts are lubricated
  • Oxidation is limited
  • Uses fuel before it degrades

    Generator maintenance

Accurate Generator Sizing

Diesel generators can be operated at high loads, upwards of 80% to 90% of its capacity. Working your generator in this manner ensures that it acquires enough combustion pressure to keep the piston rings firmly in place, and as such, the longevity of the generator is assured.

Running your generator at high loads, however, does not mean running it over its capacity. There is an assumption that the bigger, more powerful generator a business maintains, the better off it will be. This is not the case. In fact, obtaining a larger than necessary generator can impact the lifespan of the generator. Having too heavy a load for a diesel generator can result in the machine being overworked. No machine, whether it is a diesel generator, or another piece of machinery, like to be overworked. It can heat up and cause serious problems.

On the other hand, having too light a load for a diesel generator can result in several problems, too. Diesel generator sets, or gensets, whether standby- or prime-rated diesel gensets, typically are engineered to operate somewhere between 50% and 85% of its capacity. On the other hand, continuous-rated gensets are set to operate between 70% and 100% of its load. When any of these gensets run at or under 30% of their capacities, wet stacking can occur. Wet stacking is the black oil-like liquid that can leak from exhaust joints, and it leaks because the engine has not reached its minimum temperature or pressure. When the leaking occurs, it may indicate that the machine is under-loaded. If done for extended periods of time, it leads to deposit build-up that can cause things like:

  • Power loss
  • Poor performance
  • Accelerated wear
  • Cylinder line polishing
  • Engine failure

All of the above has a negative impact on the life expectancy of the generator.

Accurate generator sizing matters and the impact of an improper load size will be detrimental to the life of the diesel generator. To what extent the life of the generator is shortened depends on the extent of the over- or under-sizing of the load. Calculating the size that works best for your company involves considering the generators frequency and voltage dip as well as its recovery time. Other factors also go into the sizing calculation. If you have questions, contact us and one of our representative’s can help you calculate the right size diesel generator for your needs.

We’ve also put together a step-by-step generator sizing guide to help you calculate your power sizing needs.


Other Factors

There are a number of other factors that also affect the life of a diesel generator. These factors include but are not limited to the following:

  • Generator quality, often according to the manufacturer — major brands include Caterpillar, Cummins, MTU, Kohler, HIPOWER
  • Size of the engine
  • Installation method
  • Fuel problems, like gelling or inadequate oxygen levels, etc.
  • Availability of parts, particularly for older or outdated generators
  • Environment conditions, like extreme weather (from cold to hot), altitude, humidity, salt water and salty air, high amounts of sand and/or dust

Just about any of these things or a combination thereof can results in a shortened life of a diesel generator.  The most important two factors, however, are and will always be the care and love you provide for the machine and the accurate sizing you calculate you need in a generator.