AERA Technical Bulletins – August 19, 2022

Piston Assembly Caution on 2010-2016 GM 6.6L Duramax Diesel Engines

The AERA Technical Committee offers the following information on assembly of the pistons on 2010-2016 GM 6.6L Duramax diesel engines. Before model year 2010, the pistons for these engines were designated for left and right bank positions. 

Modification to the piston’s underside was done so now one piston serves both banks. That design change was made to better oil the piston pin. This piston Part #19301155 is directional so proper assembly to the connecting rod is critical. The formed hole shown in the photo below by the yellow arrow should go to the same side of the engine on all eight cylinders. The arrow on top of the piston indicates the front direction when assembling the rod to the piston.

Camshaft Endplay Measurement on Cummins 11.0L M Series Diesel Engines

The AERA Technical Committee offers the following information on measuring the camshaft endplay on Cummins 11.0L M series diesel engines. This information can be considered anytime the engine will not start and can be performed in-chassis. 

A condition on M series engines where the engine will not start or is difficult to start can be caused by excessive clearance between the engine position sensor and the pickup on the back of the camshaft gear. This condition prevents the engine position sensor from sending the necessary signal to the electronic control module. The excessive clearance can be caused by a failed thrust bearing on the camshaft. Use this procedure to measure the camshaft end clearance in-chassis on M series engines without removing the front gear cover.

Piston Failure: Modes and Analysis

By Eric Grilliot

An old adage goes, “success has many fathers, but failure is an orphan.” For engine builders facing premature failure of engine components, the opposite is true. Failure of components like pistons can have many possible parents. It’s the engine builder’s task to determine the true parentage – or origin – of the failure to ensure the same condition doesn’t happen again.

In this article, we will look at several real-world piston failures and examine how systematic analysis of the component pieces can help determine the cause of the failure and prescribe preventative actions.

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