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Technical Memorandum: Root Cause Analysis of Cylinder Head Oil Leak in 2.3L EcoBoost Engine (Ford Explorer, 2020-2022)
TO: Engineering and Quality Assurance Directorate FROM: Lead Failure Analysis Engineer, Propulsion Systems Division DATE: 29 May 2024 SUBJECT: Root Cause Analysis, Corrective Actions, and Preventive Measures for the 2.3L EcoBoost Cylinder Head Oil Leak (Recall 25V828)
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1.0 Problem Definition and Scope
The rapid and accurate resolution of component failures is of paramount strategic importance, directly impacting vehicle reliability, customer safety, and brand reputation. This memorandum details the findings of a comprehensive investigation into a recurring technical issue identified in the field.
The specific technical problem investigated is an oil leak originating from the cylinder head area in Ford Explorer models from model years 2020-2022 equipped with the 2.3L EcoBoost engine. Field reports and warranty data indicated a consistent failure pattern necessitating a formal root cause analysis. The scope of this analysis is strictly confined to the aforementioned vehicle models, production years, and powertrain configuration. To isolate the definitive root cause, a systematic, multi-disciplinary investigation was initiated.
2.0 Investigation and Analysis Methodology
Accurately diagnosing complex powertrain failures requires a rigorous, multi-faceted analytical approach that combines large-scale data analysis with empirical engineering tests. Our investigation integrated several methodologies to ensure a thorough and conclusive analysis, moving from broad statistical trends to the specific material properties of the failed component. The methods employed were as follows:
• Fleet Data Analysis: We aggregated and analyzed a comprehensive dataset including vehicle service histories, manufacturing records, and warranty claims. This analysis identified macro-level trends and correlations, which successfully isolated the issue to a specific production batch of a key component and narrowed the focus of our subsequent engineering tests.
• Materials Science & Chemical Analysis: To understand the physical failure mechanism, metallurgical tests and chemical composition analysis were executed on gaskets recovered from failed engines. This empirical testing was essential for comparing the as-manufactured material properties against the engineering design specification and provided direct evidence of a material deviation.
• Finite Element Analysis (FEA): FEA simulations were employed to model the complex thermomechanical stresses exerted on the cylinder head assembly under a full range of operational conditions. This method allowed our team to visualize how the identified material deviation would behave under dynamic thermal and pressure cycles, confirming the mechanism by which the seal integrity was compromised.
This integrated methodology allowed us to move methodically from a macro-level statistical signal in fleet data, to a confirmed physical deviation in material science, and finally to a predictive model of the failure mechanism via FEA, providing an irrefutable chain of evidence.
3.0 Root Cause Identification
An effective engineering response requires moving beyond addressing symptoms to identifying the singular root cause, as this is the only path to developing a permanent and robust solution. Through the rigorous application of the methods detailed above, our investigation concluded with high confidence.
The definitive root cause of the cylinder head oil leak is a material defect in the cylinder head gasket.
Elaboration on this defect revealed that the gasket material used in the affected production batches exhibited a thermal stability significantly below the required engineering design specification. This deviation rendered the material fundamentally unsuitable for this application, making eventual failure under normal operating conditions a certainty. Under normal operating temperatures, the non-compliant gasket material experienced accelerated degradation, leading to a loss of elasticity and sealing force. This material breakdown resulted in a loss of seal integrity between the cylinder head and the engine block, which allowed pressurized oil to seep out.