NHTSA Preliminary Evaluation PE20001

By letter dated August 31, 2020, Motor Coach Industries (MCI) notified the Office of Defects Investigation (ODI) of a safety defect that may exist in certain model year (MY) 2017-2020 J4500 vehicles. An ODI review of Early Warning Reporting (EWR) submissions by MCI, on MY 2017-2019 J4500 buses, identified ruptured heater hoses on multiple motor coaches leading to the vehicles becoming disabled. ODI communications with fleets found that a low coolant level light with an audible warning would provide notice to the bus driver to pull off the roadway before the bus shut down to prevent catastrophic engine damage. According to the fleets interviewed, there is not sufficient time between the warning and the engine shutting down to allow the driver to pull to a safe location. Multiple reports/interviews describe buses requiring passenger transfer to a second bus at roadside. Analysis of data provided by MCI in response to an ODI Information Request (IR) letter showed an elevated frequency of heater hose ruptures. The heater hoses may fail, resulting in a low coolant warning followed by an engine shut down sequence, as well as the potential for engine coolant spilling on the roadway. Following discussions with ODI about the elevated failure rates on the heater hoses, MCI decided to conduct safety recall 20V-526.With recall action 20V-526 taken by MCI, this investigation is closed. Further use of agency resources does not appear to be warranted.The closing of this investigation does not constitute a finding by NHTSA that a safety-related defect does not exist on other model or MY vehicles outside of the recall scope. The agency reserves the right to take further action if warranted by the circumstances.The ODI report cited above can be reviewed at: http://www-odi.nhtsa.dot.gov/owners/SearchNHTSAID Using the following identification number: 10168841