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AERA Technical Bulletins – November 3, 2021


Oil Leak and Cylinder Head Crack on 2010-2020 Cummins ISX15 CM2250 Diesel Engines


The AERA Technical Committee offers the following information on an oil leak and cylinder head crack on 2010-2020 Cummins ISX15 CM2250 diesel engines. Oil leaks resulting from this crack may result on the exhaust side of the valve cover.


The customer complaint is an external oil leak from the joint between the cylinder head and the rocker cover gasket. The cause is diagnosed as a malfunctioning rocker lever cover gasket and the gasket is replaced to correct the leak.




Timing Cover Caution on 2014-2020 GM 4.3 & 6.2L Engines


The AERA Technical Committee offers the following information regarding a timing cover caution when rebuilding on 2014-20 GM 4.3 & 6.2L engines. This issue that may occur is the crankshaft balancer contacting the timing cover on replacement engines. The following vehicle and engine combinations are most affected (see chart).


To identify if the engine has the incorrect crankshaft timing gear, inspect the gear for 5 dimples located on the crankshaft timing gear. The incorrect gear WILL NOT have the 5 dimples. If your gear shows 5 dimples, you have the correct gear. 









Before we address the subject of repairing existing threads, we’ll provide a brief overview of thread sizing.


Fractional-format fastener diameters are always referred to by inch fractional numbers (1/4″, 5/16″, 3/8″, 7/16″, 1/2″, 9/16″, 5/8″, 11/16″, 3/4″, 7/8″, 1″, etc.). Metric thread fasteners are referred to by their diameter in millimeters (4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.).


All bolts, screws, studs and nuts are identified for size based on thread diameter and thread count or thread spacing (often generically referred to as “pitch”). In the case of bolts, studs or screws, length is also part of the sizing label.


The first number always represents thread diameter. The second number always represents thread count/thread spacing. In the case of male threaded fasteners such as bolts, screws and studs, the third number represents length. Following are three examples of male threaded fastener identification…




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Podcast Episode 12 – Torque Plates


Steve and Chuck take a deep dive into the why you should use a torque plate when honing the cylinder block and its importance. Also, do you know which car manufacture and model just hit the 50 million mark in sales? They will inform you as well as which engine hit the 2 million production mark in 1955. Take a listen and subscribe to the Engine Professional podcast!




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The AERA YouTube channel features Prosis Pro tutorials, AERA webinars and membership information. We invite you to check out the wide selection of videos and subscribe! New content is added regularly.













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