Navistar International Corp. (NYSE: NAV) is recalling certain LT and RH Class 8 trucks from the 2018-2020 model years for a second time and adding 2021 models because a connector rod defect could lead to an unintended engine stall.

No crashes or injuries have been reported, Navistar told the National Highway Traffic Safety Administration (NHTSA).

The truck maker is calling back most of the 4,972 trucks recalled in the U.S. and Canada. Three on-road engine failures a year ago were related to bushing material in the small end bore, or the wrist pin of the connecting rod. 

The connecting rod may develop cracks over time or lose chunks of bushing material. The wrist pin bore of the rod was machined outside the design tolerance for straightness. 

In some cases, connecting rod failure can result in engine shutdown with minimal warning. The driver can usually pull the truck to the side of the road. But a stalled vehicle in or near the road can increase the risk of a vehicle crash, NHTSA said.

The operator may hear a knocking noise, notice an engine warning light, or experience rough idle.

The revised fix

Navistar will install new knock detection system software to warn the driver before engine connecting rod failure, which occurs in about 17% of the affected A26 engines. A red engine warning light will alert the driver to stop the engine as soon as it is safe. 

This warning sensor will be used in trucks involved in the earlier recall either didn’t have the connecting rods replaced or received an earlier sensor calibration. The new recall involves a total of 10,828 trucks in the U.S. and Canada, including certain 2021 LT and RH models.

The knock detection system software will activate the engine malfunction indicator lamp. Vehicles without this remedy either had a less-effective detection system or no detection system. Engines found with a suspect connecting rod will be repaired under the engine’s 500,000-mile warranty. 

Behind the scenes

In an uncharacteristic behind-the-scenes explanation of the 2020 recall, Navistar explained to FreightWaves its analysis of the problem and what it was doing about it..

“One of the things we did was reach out to some of these fleets’ call centers so we could find out what the driver actually reported,” Navistar Vice President of Global Product Support Mark Reiter said in a May 2020 interview. “We wanted to understand whether there were safety concerns for drivers.”

Navistar thought it had the problem under control after it changed connecting rod suppliers in December 2019 from Camtac Manufacturing, a Linamar Corp. subsidiary in Guelph, Ontario, to Albon Engineering and Manufacturing. It also installed the knock sensor in the originally recalled trucks and made a production change in  November 2020..

But in August 2020, Navistar received a report of a connector rod failure outside the original recall population. After the number of reported problems stabilized, control rod failures in non-recalled newer trucks began to rise this year, according to a chronology Navistar shared with NHTSA.

The connecting rod issue is what safety investigators call “infant mortality,” meaning it presents itself early in a vehicle’s life.The trouble occurs in the low 100,000s of miles. Trucks with higher mileage are unlikely to have the issue.

Navistar decided on the new recall April 15. Navistar expects to alert customers and International dealers to the new recall around July 8.The NHTSA  recall number is 21V-281.

Related articles:

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Navistar recalls trucks because engine revving can overwhelm parking brake

Click for more FreightWaves articles by Alan Adler.