Here's why it's complicated and what to consider:
* Engine Codes: Different years might have slightly different engine codes, even if they're still the 1.0L 3-cylinder. These codes indicate internal differences in components. A seemingly minor difference could lead to compatibility issues with your automatic transmission.
* Transmission Compatibility: The biggest hurdle is the automatic transmission. While the engine itself might seem interchangeable, the bell housing (where the engine connects to the transmission) and the engine's flexplate (or flywheel for a manual transmission) need to match your automatic transmission perfectly. A mismatch will prevent the engine from connecting.
* Wiring Harness and Computer: The engine control unit (ECU) and wiring harness are crucial. Even if the engine physically fits, the ECU and wiring harness might not be compatible with your car's system. This could lead to non-starting, poor performance, or damage to the vehicle.
* Emissions: Regulations changed over the years, and an engine from a different year might not meet your area's emissions standards. This could make it illegal to operate.
In short: While the *physical* dimensions might be similar across 1.0L 3-cylinder Geo Metro engines from various years, the *internal components and compatibility with your specific automatic transmission and ECU* are the primary concerns. It's not a simple swap, and you should prioritize finding an engine with the *exact same engine code* as your original. Trying to use an engine from a different year dramatically increases the risk of encountering unexpected problems. Checking engine codes in a parts database would be your best starting point.
