Navistar has pledged to outright replace any engines that exhibit the signs of the potential defect, which the company estimates will number about 600 units.
The 12-liter A26 engine was introduced three years ago and marked a new beginning for the truck maker as it put to pasture its 13-liter N Series. In the years since, nearly 23,500 A26 engines have been built in Huntsville, Ala.
The failure notice, which was officially posted by NHTSA Thursday and assigned campaign No. 20V255000, affects 1,814 model year 2019-2020 RH Series and 2,685 model year 2018-2020 LT Series equipped with A26 engines. Affected engines were built between Feb. 12, 2018, and June 10, 2019, for LT Series, and Feb. 10, 2018, through June 6, 2019, for RH Series.
According to the recall report, the bushing material in the small end bore (wrist pin of rod) of the connecting rod may over time develop cracks or lose chunks of bushing material and could lead to connecting rod engine failure.
Navistar Vice President of Service Mark Reiter says the company began to see premature failures with the engine late last year and found the root cause to be related to supplier quality in a rod that connects the piston to crankshaft. The investigation was prompted in September 2019 by a carrier who suffered five A26 engine failures over a two month period.
The wrist pin bore of the connecting rod on affected engines was machined outside the design tolerance for straightness. Reiter says the company already was in the process of changing connecting rod suppliers before the reported failures started and transitioned that work to a new company last year.
