Bus 168 was finishing its route dropping off children from Cloverleaf Elementary School in Statesville in May 2021 when the driver and bus monitor noticed smoke coming from the engine.
That smoke soon turned to fire. The bus driver tried to use an onboard fire extinguisher, but it wasn’t enough.
Soon the bus was engulfed in flames, which had spread from the engine to the back of the bus, both on the roof and the undercarriage.
It would take firefighters arriving on scene to tamp down the flames, sending a thick black cloud of smoke into the air.
The incident unnerved administrators at Iredell-Statesville Schools, who were thankful no children were on the bus. A possible cause of the fire quickly became apparent, said Ricky Adams, who runs the district’s bus garage: a buildup of diesel fuel in the engine’s oil.
Bus 168 was made by International and had a MaxxForce engine.
Lawsuits filed against International’s parent company, Navistar International Corp., and complaints from Iredell-Statesville administrators describe what critics call a known design defect that can increase the chances of too much diesel fuel in the engine oil. It's an issue that can lead to increased maintenance problems or, potentially, engine fire.
An analysis by the N.C. Watchdog Reporting Network of hundreds of fuel sample records from school buses with MaxxForce engines across the state shows that oil sample tests found elevated levels of fuel in the oil more than one third of the time.
The company has not responded to multiple requests for comment on issues with its engines sent to the media email address listed on its website, either for this story or for previous reporting by network member WBTV in Charlotte last year.
Despite the known issues, state education leaders have taken a hands-off approach to the problem. But some school districts have worked to replace MaxxForce engines.
That includes Wake County, which paid about $20,000 to $32,000 apiece to replace almost all 149 of its MaxxForce 7 engines starting in 2016, according to spokesperson Matt Dees.
He said the school system is monitoring the remaining nine MaxxForce 7 engines "to determine the optimal time to replace them."
‘Our mechanics are leery of them’
In North Carolina, state data showed about 1,300 school buses with MaxxForce engines assigned to public school districts as of 2021. Of those, about 400 buses have the MaxxForce 7 engine like the one inside Bus 168 when it caught fire. Almost 900 buses have a MaxxDT engine.
All MaxxForce engines circulate exhaust through the engine in an effort to burn off excess emissions to meet federal standards.
Dees said this operation of forcing excess fuel through the oil system "caused excessive wear on the internal engine components, leading to premature failure."
It’s a process that’s come under fire in at least a half-dozen lawsuits nationwide, including one class-action suit filed by tractor-trailer owners who alleged the exhaust system caused the engine to malfunction. Navistar settled that lawsuit for $135 million in early 2020.
Officials at Iredell-Statesville Schools believe the mechanical problems may have led to the fire in May 2021.
Adams, who oversees the bus garage, pointed to fuel saturation in the oil as evidence of the problem.
Adams said the bus that caught fire had its oil changed one day before the fire. The mechanic who changed the oil took an oil sample and found 30% fuel dilution. That means 30% of the oil was actually diesel fuel.
Adams said that number should be zero.
Mechanics took an oil sample after the fire, a little more than 200 miles after the oil had been changed, and found 37% dilution.
“There’s like, seven quarts of fuel in the engine oil,” Adams said.
The N.C. Watchdog Reporting Network analyzed hundreds of pages of fuel lab reports for school systems across the state dating back to 2018, which were provided in response to public records requests.
Across those counties that provided records for all the MaxxForce buses in their fleet – Onslow, Brunswick, Northampton, Duplin, Davie, Montgomery, Washington, Martin and Iredell-Statesville – the data shows that fuel dilution issues requiring some kind of action popped up about 40% of the time.
These findings accounted for just over 50 buses across nine school systems, an analysis limited by some school districts' lack of response and gaps in the data.
Adams recommended the district not use its other Maxx7 buses until they can pinpoint the problem for sure.
“Our mechanics are leery of them, scared of them,” he said. “Frankly, I’m a little bit scared of them myself right now, simply because we don’t know exactly what happened with this one.”
No state action, despite potential danger
In Statesville, the district's burned bus now sits covered in the back of a maintenance lot.
According to Adams, Navistar has not come to inspect the bus; it has only sent a photographer to take pictures.
It's not a pretty sight, Iredell-Statesville Schools Superintendent Jeff James said.
“Looking at it actually gives you cold chills because some child could have died on that bus," James said. "It’s not a time to start trying to protect yourself, it’s a time to say, 'What’s wrong? Let’s fix the problem.'”
But the engine, as WBTV reported in August 2021, has never faced a company recall.
And state education leaders at the N.C. Department of Public Instruction have said repeatedly that the agency had no responsibility to warn other districts of the potential danger, even though a spokeswoman for the agency told WBTV last year that staff was tracking the problem.
“While NCDPI advises districts on maintenance of equipment based on the NC School Bus Fleet Manual, the agency does not have daily oversight and refers to the experience and expertise of those on the ground,” spokeswoman Blair Rhoades said in a statement in August.
“These preventative maintenance processes in place – which include oil analysis and inspection of oil level and condition – are to ensure buses are safe and to allow technicians to report problems that may require additional monitoring,” the statement continued. “Districts are to use the results of these analyses to make informed decisions about vehicle condition and operation.”
Iredell-Statesville Schools took their buses with Maxx7 engines off the road. Doing so means the district had to find additional buses with their own money – a price worth paying, James said, for the safety of the students.
“This is serious. Somebody needs to get serious about it from all points," he said. "We’re trying to, I guess, ring the bell and say there’s an issue.”
This story was jointly reported and edited by Kate Martin, Shelby Harris and Ben Sessoms of Carolina Public Press; Sara Coello of The Charlotte Observer; Tyler Dukes and Jordan Schrader of The News & Observer; Nick Ochsner and Joseph Collins of WBTV; Michael Praats of WECT; Travis Fain and Ali Ingersoll of WRAL; and Jason deBruyn of WUNC.
How we analyzed hundreds of pages of fuel reports
Earlier this year, the N.C. Watchdog Reporting Network requested oil sample testing results for school buses with MaxxForce engines from every North Carolina public school district. The goal was to examine the records for results of high fuel dilution, which experts have said can pose both safety and maintenance issues.
About two dozen school systems, out of the more than 90 with MaxxForce engines, provided records.
Reporters removed duplicate sample reports and any reports from non-MaxxForce engines or engines where the make and model weren't clear. Reporters then tracked how many times fuel dilution was marked as a problem requiring some kind of corrective action to maintain the engine, often oil changes or additional inspections.
Data for a given school system was removed if the number of buses with MaxxForce engines in the records didn't match the number of buses according to data from the state Department of Public Instruction, which may have indicated gaps in testing or document production.
The resulting records included about 350 tests of about 50 buses from Onslow, Brunswick, Northampton, Duplin, Davie, Montgomery, Washington, Martin and Iredell-Statesville school systems.
