Skoolie Buses: How Long Do They Really Last?

A Skoolie engine will not last more than 20 years or 250,000 miles, but with proper care, a Skoolie can last a very long time. The lifespan of a Skoolie depends on several factors, including maintenance, usage, and mechanical condition.

When considering the purchase of a Skoolie, it is important to examine the mileage and engine hours. While a lower combination of mileage and engine hours is generally preferable, a well-maintained diesel engine with higher mileage can still be reliable. It is also crucial to consider the type of engine, with the DT466 and 5.9 Cummins engines being popular choices due to their power, reliability, and ease of maintenance.

In addition to engine specifications, other factors such as bus size, layout, and personal preferences should be taken into account when choosing a Skoolie. The number of windows on a bus can provide an estimate of its length, with each window representing approximately 2.5 feet. Short buses (20-25 feet) offer maneuverability and ease of parking, while medium-size buses (25-35 feet) provide a balance between space and accessibility. Full-size buses (35 feet and above) provide ample room but come with a learning curve for driving and parking challenges.

Furthermore, the location of the engine (front or rear) and the ceiling height are important considerations, as they impact the interior space and functionality of the Skoolie. It is also essential to inspect the bus for rust, especially in regions with road salt during winters, as excessive rust can be a sign of potential issues.

Overall, the longevity of a Skoolie depends on a combination of factors, including engine specifications, maintenance, and personal preferences for size and layout. By conducting thorough research and inspections, individuals can make informed decisions when choosing a Skoolie that meets their needs and ensures a lasting investment.

Engines: diesel vs. gas, and the best types

Diesel engines are the norm for skoolie conversions, as it is rarer to find gasoline engines. LPG or GPL (propane) will cost a fortune for a road trip, and you can't find it everywhere. Diesel, on the other hand, is always found ubiquitously.

Diesel Engines

The most common brand of skoolie engines you’re going to see are:

• International Navistar MaxxForce DT (DT466)
• Cummins (5.9L, 6.7L and 8.3L)

The International DT466 is used in many different applications, not just school buses, and has been manufactured for over 25 years. Its nickname, ‘The Legend’, was coined by users in the field before Navistar themselves started marketing it as such. This engine definitely earned its reputation. When the 300 & 400 series DT466 engines were introduced, it was 'the right engine and the right time' in terms of technology and a solid base to grow on for years to come. That’s why this engine is still very popular and reputable today while still being widely used.

The Cummins 5.9L is one of the most common diesel engines on the market as well. School buses after 2009 will have the newer, environmentally friendlier option, 6.7L Cummins.

Although the smaller CAT 3126 engines do have a less positive sentiment from buyers, the C7 & 3126 engine configurations are the same in most aspects. CAT stopped manufacturing the C7 in 2009 so as we move along in the years to come, parts might become harder to find. In saying this, there are plenty of skoolies with CAT engines that last a long time if properly maintained.

According to Diesel Hub, an engine with a wet cylinder sleeve design, like the DT466, allows for less downtime and reduced repair costs. This means that an engine overhaul can be done without removing the engine from the chassis.

Gas Engines

As for gas engines, just stay away. In general, gas engines are not a good idea for skoolie conversions. One source states that "you should plan for a new gas engine somewhere around 75k miles even with a modern engine." Another source states that "gas buses [...] get about 5 mpg or less."

Best Engines

The most reliable and powerful engines are the International DT466 and the Cummins 8.3, however, these are generally found in the largest buses. The less powerful versions of these engines found in shorter buses are the International T444E and the Cummins 5.9.

Other engines to consider are the Detroit Diesel 6V92 and 8V71. These extremely robust engines, used for decades in Greyhound coaches, are old, dirty (as they burn and leak oil by design), and are not terribly fuel-efficient, but they are basic, powerful, and very hard to kill.

The Caterpillar CAT 3116 and the Mercedes Benz MBE906 are generally avoided by bus builders due to a significantly higher cost of repair and more known reliability issues. However, if you don’t plan to drive your bus much, or at all, or you happen to be a whiz mechanic, you may find the perfect platform for your Skoolie conversion with one of these engines.

Age and mileage

The lifespan of a Skoolie engine is thought to be around 20 years or 250,000 miles, but this is dependent on how well the vehicle is maintained. Some sources suggest that a Skoolie engine will not last longer than this, while others suggest that a well-maintained diesel engine can last indefinitely.

When buying a used Skoolie, it is recommended to look for one with under 200,000 miles on the clock. One source suggests that anything under 150,000 miles is best. However, it is important to note that diesel engines are built to be running more frequently and for longer than standard family vehicles, so higher mileage is to be expected.

One source suggests that a good rule of thumb is to look for a well-maintained gas-powered bus with under 100,000 miles, or a well-maintained diesel bus with under 200,000 miles. Another source recommends looking for a bus with mileage between 150,000 and 200,000.

It is also worth noting that some Skoolie engines will not even make it to seven years due to various causes of wear and breakdowns.

When it comes to engine hours, it is recommended to look for a bus with fewer hours rather than more. One source suggests that anything under 20,000 hours is acceptable, while another recommends looking for a bus with under 12,000 hours.

In addition to age and mileage, it is important to consider the maintenance history of the bus. A bus that has been regularly serviced and well-maintained is likely to last longer than one that has not. It is also a good idea to inspect the bus for any signs of rust, as this can be a common issue, especially in older buses or those from colder climates where road salt is used in winter.

Finally, it is worth considering the type of engine the Skoolie has. Some engines are known to be more reliable and easier to work on than others. For example, the DT466 and 5.9 Cummins engines are generally reliable and powerful, while the VT365 and 6.0 Cummins engines should be avoided unless they have been bulletproofed.

Size and length

The size and length of a Skoolie bus are important factors to consider when planning a conversion project. The three primary types of school bus sizes are short buses (20-25 ft), medium-size buses (25-35 ft), and full-size buses/coach buses (35 ft+). Here are some key points to consider for each size category:

Short Buses (20-25 ft)

• A smaller bus is more manoeuvrable and can fit into most parking spots, making it easier to run errands.
• Ideal for 1-2 people who are not interested in towing an additional car or accessing harder-to-reach boondocking spots.
• The main downside is the significant loss of living space, which may require compromises in the build, such as excluding a toilet or shower.

Medium-Size Buses (25-35 ft)

• Offer a happy medium between a short and full-size bus, providing plenty of interior room without sacrificing manoeuvrability.
• Ideal for 2 people, pets, and even children if space restrictions are not a concern.
• More difficult to find and tend to be more expensive.
• May not fit into a single parking space.

Full-Size Buses/Coach Buses (35 ft+)

• Provide a generous amount of room, making them ideal for 3 or more people.
• Can be challenging to drive and finding parking is difficult, especially in populated areas.
• Towing a vehicle as a primary means of transportation is often necessary.
• Affordability varies, but there are plenty of affordable options on the market.

When choosing a Skoolie bus size, it's important to consider your specific needs and constraints. Factors such as the number of people, pets, desired features (e.g., toilet, shower), manoeuvrability, parking availability, and budget should all be taken into account. Additionally, the location of the engine (dognose vs. flatnose) and the space available for the conversion process should also be considered.

Rust and mechanical issues

Rust Issues:

• Rust is the primary enemy of school bus conversions. Transport professionals consider rust to be the biggest problem on buses as it attacks the chassis, the backbone of the bus. If the chassis breaks, the bus is beyond repair.
• In buses 12 years or older, it is challenging to find a model entirely free of rust. The task is to determine whether the rust is surface-level or has started eating away at the structure.
• Surface rust can be treated by grinding and applying a protective coating. However, if there is extensive pitted rust in the undercarriage or side skirts, it is best to move on to another bus.
• Rust on the wheel bolts is a red flag, indicating that they are loose.
• Buyers should carefully inspect the underbelly of the bus for any signs of cancerous rust that could compromise the integrity of the metal structure.
• Buyers from the Southern states have the advantage of being more selective and can find buses with minimal or no rust.

Mechanical Issues:

• A well-maintained Skoolie engine can last up to 20 years or 250,000 miles. However, without proper care, engines may fail to reach even seven years.
• Frequent breakdowns in diesel school bus engines include issues with the particulate filter, the turbo, and the dual-mass flywheel.
• To increase the lifespan of a Skoolie, regular maintenance is crucial. Refer to the maintenance book for guidance on tasks such as oil changes, which should be done on average every 15,000 miles.
• Replacing worn parts such as the oil filter and timing belt can improve fuel consumption and durability.
• Letting the Skoolie warm up slowly is advisable, as it ensures the engine oil is more fluid and effective.
• Buyers should be cautious of buses with extremely high mileage, as they may require significant repairs upfront.
• A pre-purchase inspection by a reputable mechanic is essential to identify any hidden mechanical issues.
• Engines such as the DT466, 5.9 Cummins, and 8.3 Cummins are generally reliable when properly maintained. However, specific engines like the VT365s, 6.0 Cummins, and Mercedes MBE engines are best avoided due to their higher maintenance costs and complexity.
• The ideal mileage for a diesel engine is under 200,000 miles, while for a gas engine, it is under 100,000 miles.

Ceiling height

When converting a skoolie, the ceiling height is an important factor to consider, especially if you are tall. Ceiling heights can range from 74" to 78", and many people choose to do roof raises for extra headroom. If you are not keen on the task of a roof raise, then checking out buses in person to determine a comfortable ceiling height is crucial.

For example, if you are 5'7" or shorter, a 76" ceiling will likely be comfortable. However, if you are taller, you may need a bus with a 78" ceiling, which can be harder to come by.

Additionally, keep in mind that redoing the ceiling and floors during the conversion process will reduce the overall ceiling height, so choosing a bus with a higher ceiling than you think you need may be beneficial.

When considering ceiling height, it is also important to think about the type of engine your bus has. A rear engine will reduce the amount of usable space in the interior, while a front engine will provide more usable floor plan space.

Frequently asked questions