Cummins ISB Diesel Engine Performance Report

If you’ve been following my posts and videos I can’t say enough about the Cummns ISB diesel engines which are by far the best medium duty engines on the market. They are not 100% perfect but weighing them against the other available diesel engines there is no comparison to their dependibility and performance. The three year purchase of nothing but International MaxxForce diesel engines sunk us for a long time trying to keep up.

The cost we have incurred with international engine repairs not covered by warranty has been in the 5 figure range. This should have never happened considering we are operating a fleet of school buses for half a day, 5 days a week not including field trips for only 9 months a year. In the past before emission controlled diesels a school bus engine lasted the life of the bus except for the high mileage units that were just plain worn out. We would rebuild them depending on the years of life left which was 12 years or 325,000 km for conventional buses and 15 years or 450,000 km for rear engine buses.

In the video the VGT (variable geometry turbo) worked like a charm but even better with the ECON switch off. The driver reported no hold back at highway speed and I have to agree I did not feel the exhaust brake working correctly at highway speed. The ECON switch for some reason was the difference…with the second road test ECON switch off the VGT worked much better with a faster response.

The VGT also helps with the forced regen creating back pressure and heat to burn out the DPF down the line. The SCR selective catalytic reduction system that follows the DPF works extremely well to keep the system clean. The uptime with our buses running the ISB engines are way ahead of all the other brands in our fleet. If a component fails it’s expensive not unlike any other diesel engine on the road but if it lasts for 8 or 9 years that’s very acceptable. Premature failures are hard to take due to poor engineering.

In closing since 2014 our fleet has been equipped with all Cummins diesel engines and we will not choose any other model in the future. They have been running steady without any major issues and gave us the breathing room to tackle the constant problems and failures with the International diesel engines. Out of 18 MaxxForce diesels in our fleet bought between 2010 and 2013 there have been 8 engine rebuilds and replacements. There is enough work going on with inspections, maintenance and ongoing repairs so unexpected failures do not help us keep up with our program.