After extensive teardown and inspection of an LZ0 Duramax engine with thrust bearing failure at just over 7,500 miles, it was discovered that the engine was missing one of its two thrust bearings from the factory. This missing bearing caused excessive crankshaft end play, low oil pressure, and ultimately engine failure. The investigation dispels previous misconceptions about the failure cause and provides clarity for owners and mechanics.
The LZ0 Duramax engine has been experiencing thrust bearing failures, often blamed on various issues. However, a recent detailed teardown and inspection of an LZ0 engine that failed just over 7,500 miles has shed new light on the true cause of these failures.
Typically, when thrust bearings fail, the bearings are found in the engine oil pan, and the engine often ceases to run. In this case, the engine was still running despite low oil pressure and significant crankshaft end play, which indicated a need for replacement.
Interestingly, the engine oil pan contained only one thrust bearing piece, which was unusual since the engine should have two thrust bearings controlling the crankshaft's forward and backward movement.
The investigation involved a comprehensive teardown:
Throughout the teardown, a significant amount of metal debris, including pieces of the thrust bearing and threaded chunks, was found in the oil pan.
Missing Thrust Bearing: The engine appeared to be missing one of the two thrust bearings from the factory. Only one complete thrust bearing was found, with fragments of another.
Crankshaft End Play: The missing thrust bearing caused excessive crankshaft end play, which led to the failure.
Oil Pressure Loss: The excessive movement caused damage to the piston oil squirter, contributing to low oil pressure and triggering engine codes.
Oil Pump Belt: The oil pump belt, often blamed for failures, was found to be within acceptable limits and not the cause.
Oil Pan Design: The newer oil pan design includes a drain plug in a different location, which helps in oil changes and oil retention.
This discovery suggests that some LZ0 Duramax engines may have been assembled with only one thrust bearing instead of two, potentially from the factory. This assembly error leads to premature thrust bearing failure, low oil pressure, and engine damage.
For owners and mechanics, this means:
The investigation into the LZ0 Duramax thrust bearing failures reveals that the root cause is likely a missing thrust bearing from the factory, not issues with the oil pump belt or other previously suspected components. This insight should help alleviate concerns and guide proper diagnosis and repair.
For those interested, a detailed comparison video between the LZ0 and the LM2 Duramax engines is recommended to further understand the differences and improvements.
Until next time, stay informed and keep your engines running smoothly!
