How long do diesel school bus engines last?

In this blog post, we will answer the following question: How long do diesel school bus engines last? We will discuss how to prolong the life of your school bus engine and many other interesting details about diesel Skoolie engines. 

How long do diesel school bus engines last?

Diesel school bus engines last 15 to 20 years or 250,000 miles if properly maintained and treated with care. 

In rare cases, the Skoolie engines will not even get to seven years, as the causes of wear and breakdowns are plenty. As the diesel engines were equipped with new components over the years, new failures related to these parts appeared. In rare cases, motorists have even witnessed the breakage of these parts. 

Frequent breakdowns in diesel school bus engines today include:

  • The injection pump,
  • The injectors,
  • The EGR valve,
  • The particulate filter, however essential to reduce the amount of fine particles emitted in the exhaust.
  • The turbo, which tends to clog and is one of the common causes of engine failure.
  • The dual-mass flywheel, a transmission part commonly found on diesel models and known to break more often than rigid flywheels.

However, it must be admitted that manufacturers now master the design of these parts. While faults can still be observed on certain ranges, the fouling and breakage of engine parts are on the whole less numerous.

How to extend the life of a diesel school bus engine

Whether you choose a gasoline or diesel vehicle, certain simple actions will help improve the life of your school bus engine:

  1. Refer to the maintenance book for your vehicle. This mentions the frequency of the tasks (such as oil change, for example, which must be carried out every 15,000 miles on average).
  2. Replace wearing parts: Elements such as the oil filter or the timing belt influence a vehicle’s fuel consumption, but also its durability.
  1. For a used bus, choose manufacturer parts, in particular for your engine parts. These are more expensive, but are generally more enduring.
  1. Let your vehicle warm up slowly. When warm, the engine oil will be more fluid and will do its job better.
  1. If your school bus has one, use the Start & Stop. This helps to preserve the condition of the engine by reducing its use.

To this, we can add some advice specific to school buses that run on diesel:

  1. Premium diesel fuels have a higher price per liter, but they promote better combustion. These automotive fuels also help preserve the engine.
  1. Various additives designed for diesel cars can help make your vehicle less polluting or more economical. Others can help preserve the condition of the engine block.

Diesel or gasoline engine for a Skoolie?

Historically, diesel engines have long been considered more enduring than their gasoline counterparts. One of the reasons for this is that a diesel engine runs slower than a gasoline vehicle. In addition, until the 1980s, diesel vehicles benefited from a simpler design, which promoted high reliability.

Later, however, these engines were made more complex. They are now equipped with turbo and high-pressure injectors. These additions have improved the performance of each car, but also undermined their reliability: these parts are now responsible for many breakdowns.

Today’s diesel vehicles no longer correspond to the opinion still anchored in many minds, who consider that this type of fuel is synonymous with an indestructible engine.

But if the diesel models have seen their robustness decline in recent decades, they remain on average more enduring than the petrol versions. If thermal engines (diesel as gasoline) would have a similar lifespan, a diesel model would travel on average 16,000 miles per year, compared to 9,300 annually for gasoline. 

In terms of mileage, the average lifespan of diesel would therefore be 155,000 miles, compared to 60,000 miles less for gasoline.

Are bus engines turbocharged?

Yes, most of the bus engines made in the past few decades are turbocharged.  On buses, the engine is generally installed at the rear, lying down on the left side to free up space in front of the rear door, or upright, which allows better access for maintenance. There are also mid-engined buses and there are older buses that are not turbocharged.

Turbocharged engines currently offered for buses are from:

  • Iveco
  • Tector 7 (midibus and bus)
  • Cursor 9 (bus)
  • MAN
  • Engines D 0836 LOH
  • Mercedes
  • OM 906 hLA (170 kW or 205 kW)
  • OM 457 hLA (185 kW or 220 kW)
  • Volvo
  • D7C.

The engines have followed the evolution of standards. Now all are Euro 6 compliant. And the technical developments have led manufacturers to release new engines. The latest engines have higher power for smaller displacements.

How to prevent damage to a bus engine?

Most problems related to the turbocharger can be avoided with regular maintenance of your car. To prevent turbo failures, be sure to regularly change the engine to replace the oil and filter. 

Also, be sure to check the engine oil level and clean the air filter. By doing this, you are ensuring that your turbocharger stays in good condition for as long as possible and you avoid early repairs or replacement.

One of the most common problems is turbocharger fouling from debris or dirt in the oil.

A lack of oil in the engine can damage the turbine engine irreversibly and lead to an expensive replacement. Conversely, too much engine oil can raise the temperature and damage the turbine engine. Most problems with excessively high temperatures are triggered by faults in the ignition or fuel injection system.

How efficient are school buses engines?

Despite their dimensions, school buses are more fuel-efficient than trucks and semi-trucks. On average, a school bus or a Skoolie has a 30% fuel consumption, with 10  mpg!

Besides, diesel Skoolies are more fuel-efficient than gas buses. On average, a diesel school bus can travel about 510 miles on a diesel tank versus just 270 miles on gasoline, based on the same standard size gasoline tank.

Of course, how fuel-efficient your Skoolie is going to be, will also depend on the type of chassis you are going to install and engine power. See the table below for more information. 

Skoolies Average Fuel Consumption

Chassis typeEngine PowerAverage consumption
Chevy/GMC 6.0L/6L80 or 6.0L/8L8013 MPG
Ford V-10/E4OD11 MPG
Chevy/GMC & Duramax6.0L/6L80 or 6.0L/8L8014 MPG
Ford6.0L 13 MPG
Ford7.3L14 MPG
Ford460 V-87 MPG
Chevy/GMC6.2L V-813 MPG
Chevy/GMC6.5L turbo-diesel V-814 MPG

FAQ on How long do diesel school bus engines last?

Do school buses get good gas mileage?

Yes, school buses get good gas mileage. A Skollie can get an average of 10 miles per gallon, which is pretty good for a bus. 

What is the best diesel engine for an RV?

If your budget allows it, the best diesel engine for a motorhome is an engine greater than 100 hp. You will have more comfort with a more powerful and more torquey engine, especially if you are travelling with a large payload. 

How to make the best of your diesel engine?

The following tips should help you reduce your fuel consumption and take the best from your diesel engine. A motorhome consumes between 12 and 30 litres per 100 kilometres depending on the engine and the size, we assume that if you take the road in a motorhome, it is certain that you are going on vacation or for the weekend.


Was this helpful?

Thanks for your feedback!