Mercruiser Serial Number FAQs

The serial number on a Mercruiser engine is typically located on the block near the starter or flywheel. In some models, you may find it on the flame arrestor. This number is essential for identifying the correct parts for your engine. According to Mercury Marine’s official guidelines, serial numbers are the only reliable way to confirm your engine’s part compatibility or production year.

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 to find serial number on a mercury outboard or Mercruiser engine?

Wondering where the serial number is on a Mercury boat motor? On a Mercruiser sterndrive or inboard engine, the serial number tag is usually located on the block near the starter. In other models, check near the flywheel or on the flame arrestor. If you have a Mercury outboard, the serial number is often on the transom bracket. Always take a photo and save it—these tags can wear off over time.

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.

Tip: To locate the serial number on a Mercury outboard engine, inspect the transom bracket, which is where the motor mounts to the boat. This number is essential for determining the engine’s model year.

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.

Frequently asked questions about Mercruiser and Mercury serial numbers

Where is the serial number on a Mercury outboard engine?

You can find the serial number on the transom bracket of your Mercury outboard. It’s usually on a sticker or metal plate and is required when identifying parts or the model year.

How do I decode a Mercury outboard VIN number or serial number?

Mercury doesn’t use traditional 17-digit VINs. Instead, your serial number can be entered into a Mercury Marine serial number to year lookup tool to determine the engine’s model and year.

What is the format of a Mercruiser serial number?

Mercruiser serial numbers are formatted like “0W555555,” beginning with a “0” followed by a letter and six digits. Engines made before 1980 may use a seven-digit numerical format instead.

Quick summary: How to find and use your Mercruiser serial number

• Look near the starter, flywheel, or flame arrestor
• Mercury outboards usually have the serial number on the transom bracket
• Serial number format is typically “0W######”
• Use the serial number to find compatible parts and determine model year

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.