Mercruiser Serial Number FAQs

Members of the PartsVu community frequently ask us where to find their Mercruiser serial number. Like other Mercury engines, the serial number is essential when ordering Mercruiser parts.

Where Is My Serial Number?

Typically, on a Mercruiser sterndrive or inboard engine, the tag is on the block near the starter. But, sometimes, it’s down by the starter on the engine block, near the flywheel, or on the flame arrestor.

All too often, the ESN tag on a Mercruiser is not the easiest to find, so definitely take a picture and save it on your cell phone.

Why Do You Need to Know Your Serial Number?

Simply put, your serial number will allow you to identify and order the correct parts for your engine model and year. Mercury manufactures many, many different models and often variations of each model. While one thermostat might be the proper selection for some variations of a given engine model, there’s no guarantee that it will be compatible will all variations of that engine—knowing your serial number is the key.

As if matters weren’t confusing enough, sometimes Mercury will change a Mercruiser engine model design midway thru a given engine model year. Therefore, Mercruiser parts are often segmented by serial number ranges. Knowing your serial number will allow you to make sure that you are ordering the right parts, whether you are utilizing a Mercruiser engine schematic, Mercruiser Parts charts, the complete catalog of Mercruiser parts, or other resources.

Are Mercruiser Serial Numbers Specifically Formatted?

Mercruiser sterndrive engine serial numbers are formatted as follows—0W555555. The first character is the number 0, not the capital letter O. Serial numbers that do not follow this format, rather have seven numerical digits, were manufactured before 1980.

PartsVu is proud to carry a full selection of Mercruiser parts, and our mission is to make finding the right parts for your specific engine as easy as possible.