The Cummins ISB diesel engine is a great piece of machinery and my first choice any day. It comes with the Allison 2500 series automatic transmission in our conventional buses and they work together extremely well. Those 2 components have given us minimal breakdowns. I shouldn’t say breakdowns more like minor inconveniences.
The 250 horsepower ISB runs on a common rail high pressure fuel system and incorporates the VGT variable geometry turbocharger to not only supply boost but also act as the exhaust brake and help create back pressure to create heat when doing a parked regeneration.
The engineers obviously care about the mechanics who work on their engine because of the accessibility of the maintenance items especially the engine crankcase filter which is on top of the valve cover and easily replaced in 15 minutes. The DT MaxxForce inline six Navistar models has their crankcase filter down deep inside the frame and takes 2 to 3 hours to replace.
Cummins also has the SCR selective catalytic reduction system and diesel exhaust fluid to reduce emissions even further on top of the diesel particulate filter on the down side of the exhaust system. They are thinking about the future designing an emission controlled diesel engine that meets the EPA demands and keeps us end users happy with a dependable and maintenance friendly engine.
One simple yet huge asset to the ISB is they come from the factory with a Horton fan clutch system (newer models use the Warner electric clutch). It does not activate until the engine temperature gets up to a set parameter. The amount of horsepower saved and the quiet running operation is favorable with drivers and us mechanics.
Cummins Insite Lite software is a great tool to have when checking out engine codes. There are lots of areas of resource to keep on top of the problem with step by step troubleshooting for each code. This software is used to regen the exhaust system as well so it’s invaluable and without it you’re sunk.
The bus in the video is a 2015 Thomas C2 which has developed into a well designed school bus with changes to the modules and where they are located. They are less exposed to the atmosphere which in the past caused corrosion issues creating a lot of problems. They did listen and made changes to reduce electrical problems. The C2 has some advantages over the Navistar school bus with sturdier crossview mirrors and the Horton or Warner engine fan clutch.
Simple design changes go a long way requiring less design changes on our side of the fence saving money and time. In a nutshell I highly recommend the ISB diesel engine for any application. Mechanics and operators will thank you for choosing this model.