By Francisco Aristizabal
Failure analysis theory in internal combustion engines occurs in stages and is a detailed process that allows you to identify in a scientific way the root causes of the failures. Engine operation conditions must be considered, the failed parts, and all related info to find and correct the causes for a proper repair.
As a first step, all the history about previous maintenance operations scheduled or not must be analyzed, and all the information included in the last report of the operation parameters before the failure as well; finally, the failed parts, no matter how much are broken or damaged, must be prepared to be checked, rightly tagged and classified.
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OEM, aftermarket parts manufacturers, AERA and other technical information must all be considered. The causes of the failures could be roughly classified in four groups according to their origin: Failures due to bad engine operation (55%), lack of maintenance (34%), assembly failures in repair process (10%) and defective spare parts (1%).
Engine Operation (55%)
This group includes: fast/cold starting, overspeed, excessive idle rating, high operation temperature, low oil level could generate premature wear in parts like piston rings or engine bearings.
Maintenance Problems (34%)
Poor maintenance / service with oil change intervals, coolant, fuel, or air systems, could generate common failures like cavitation, retarded/advanced injections, even failures like seized pistons.
Assembly/Machining Failures in Repair and/or Rebuild Processes (10%)
Here, failures like cylinder distortion, bad honing techniques, valve guide issues (valve guide sizing process), utilizing wrong specifications / break-in procedures, can cause issues like oil high consumption, and other lube system problems.
Defective Spare Parts (1%)
Finally, in this group, no matter if they are OEM or aftermarket parts, wrong design supplied/applied parts, dimensional errors or inappropriate materials are included. Issues such as failed pistons due to a wrong selection or application in the oil cooling (marine is different from truck applications design as example) are relatively common. 95% of the time, these kinds of failures can be prevented. To avoid this kind of failure, check before installing the parts.
To identify the failure and their cause(s), the correction stage is necessary. Follow all the procedures and recommendations as per the OEM, service literature and standards, and keep a summary for the records including data and conclusions is the next step.
There are several failure handbooks (including our own AERA Failure Analysis Manual) and some are focused primarily on other components like pistons or bearings. Overall focus is the key to not having a complete engine failure, most of time it is a combination of causes for the failure to occur.
As always, we mention all this info as it is intended to serve as a general guide. Specific information may vary depending on the equipment manufacturer and application. Always check their literature and any other OEM service material. The AERA tech line is also available to solve questions on these matters.
Read this article with all images in the digital issue of Engine Professional magazine https://engineprofessional.com/2025EPQ3/#p=78