If you’re new to this (we were!), it’s tough that one of the first things you do is probably the most critical. There are a lot of decisions to be made to try to get the bus that’s right for you. This is the first in a series of posts aimed at helping to choose the right bus for you.
When choosing a bus, a common thing you will hear is to not get too new of a bus. This seems counterintuitive if you don’t understand the reasoning behind it If you’re buying a car, you probably want the newest car you can afford, right?
Well, buses are a different breed. This entire post can be summarized as such: Don’t buy a bus newer than 2003, and try to get ond older than 1995. Now let’s talk about why!
Diesel engines are a different animal from gasoline engines. They are far less complex in operation and construction. A mid-1990s Cummins engine is hardly any more complex than the original turbo diesels of the 1920s. One of these mechanical diesel engines can run just fine with only a single wire attached, literally just enabling the injection pump.
In the 1990s, things got a bit more complex, but a lot of it was cosmetic. Sensors started appearing all over the engine, but actually did very little with regards to the engine running. Your ECU now knew your engine’s temperature, oil pressure, turbo boost pressure, etc, but didn’t do much with it other than log events and turn on warning lights. Things got weirder as the 90s went on, suddenly you had things like Exhaust Back Pressure Valves and glow plug controllers that keep them on as long as 4 minutes after the engine is started. But these are relatively minor, they are fairly well known things, and the fixes are usually very simple and often free.
Things changed in 2004.
2004 was the first year of tighter emissions regulations pushed on the heavy duty diesel market. Even though they had 7 years notice, it’s fair to say these guys were caught with their pants down. The introduction of the EGR system into these engines proved to make them fragile ticking time bombs. Probably the worst of which was Navistar’s VT365, also known as the Ford Powerstroke 6.0. These problems plagued the entire industry, and it wasn’t until 2010 or so that you could expect to buy a school bus that would last half as long as the one it was replacing.
The next series of engines brought in our new friend, Diesel Exhaust Fluid. These engines have an added tank for this fluid, which has an active ingredient of urea (Yes, urea, as in pee.. But don’t just pee in your DEF tank!) that gets sprayed into the catalyst system to reduce emissions. These newer engines also further increased its dependence on its electronics, making them poor choices for a DIY-er. Also, while they aren’t so prone to exploding from a plastic part inside the engine melting, they have another really good reason to avoid them. Quite simply, the used market for late model buses includes schools and other organizations that use them as school buses. These companies are not afraid to spend $25k, $30, or more because they are still saving 75% from the price of buying new.
Most skoolies out there will have been built between 1988 and 2003. This is the sweet spot where you can get a good price, reliability, affordable and easily available parts, in a platform you can work on yourself.