What should technicians do before working on a tampered engine?

Before working on a tampered engine, technicians should record the tampering. Documenting any modifications or alterations to the engine is crucial for several reasons. It provides a clear record of the work that has been done outside manufacturer specifications, which can affect performance and reliability. This documentation is essential for diagnosing issues correctly, as tampered components may not function as intended or could introduce new problems that wouldn't be present in a standard setup.

Additionally, having a record of the tampering ensures that any further repairs or modifications are informed decisions, based on a comprehensive understanding of the engine's current condition. This approach also aids in maintaining compliance with legal regulations or standards concerning emissions and engine performance.

In contrast, rebuilding the entire engine or replacing all worn parts might not address the fundamental issues caused by tampering and could lead to unnecessary expenses. Adjusting the fuel mixture might also prove ineffective without understanding the specific changes made during the tampering process. Therefore, recording the tampering is the practical and necessary first step to ensure accurate and effective repairs.