A boat owner should know what engine is in their boat. Why? The engine manufacturer, and serial number are critical pieces of information for mechanical service and part replacement. Service centers will need this information to ensure OEM parts. Having the hull identification number (HIN) handy is also helpful.

Whether it’s an outboard, an inboard, or I/O with sterndrive knowing where to look for important information is key. Once you’ve located the serial information, documenting elsewhere will save time when there’s a need for future service.

Main Engine Information

Many engines will have the model and serial number on top of the engine cover, or on older models it may be located on the

rocker cover. However, there are instances where the engine cover has been replaced, or numbers have worn and become illegible over time, which creates a challenge. Most Mercury engines also have the serial number on the starboard side of the flywheel housing, above the starter motor, but this is not the most efficient or easy method to find it. See image below, or check out this post for help with older models.

On Volvo Penta engines, model and serial information is typically located on the engine cover as well. Volvo has a very helpful guide on their website that provides examples of where to find the product information for main engine, and sterndrive lines.

Sterndrive Information

Mercury’s sterndrive lines (Alpha and Bravo) have multiple places where serial information can be found, along with the transom assembly serial number. The importance of serial information is critical when it comes to determining parts. There are instances when parts change from one model year to the next, and having the proper identifying information is key. Below are a couple images of Mercury’s most common sterndrives: Alpha and Bravo drives. They show where the transom assembly serial information is located along with the drive serial number and the drive gear ratio.



Knowing the basic information for your boat’s engine should be high on the list of every boat owner. It is extremely helpful when looking for a service center, or when searching for repair parts.

For more information, please do not hesitate to reach out to our service department at any time: Service@chicagoyachtworks.com.