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.
409 comments
I recently purchased a used boat that had a complete repower done a few years ago. Can you verify the year of this engine, please?
I have two serial numbers listed on the plate beside the arrestor:
350 MAG Bravo
8M0150496
8M200111
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PartsVu replied:
Hi Blake,
Thanks for the info — unfortunately, the numbers you provided (8M0150496 and 8M200111) are not pulling up as valid engine serial numbers in the MerCruiser system. To verify the exact year of your 350 MAG Bravo engine, please double-check the serial number on the mounting bracket of the engine and also inside the top cowling (these are the most reliable locations for the actual serial number tag/sticker).
Once you’re able to confirm that number, feel free to send it over and I’ll be happy to take another look for you!
Best Regards Markine
Hello, I purchased a used boat and I am certain the engine is much older then the stern drive or boat itself. The boat is a 2001 wellcraft, but the vin number on the engine is only 7 digits. I need a starter for said engine but I don’t know the year of it.
VIN # 6696861 – Mercruiser 3.0 (140 horsepower)I suspect the engine is pre 1980 but could anyone confirm the year and the proper part number for the starter?
Thanks!
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PartsVu replied:
Hi Tyler, The serial number you provided (6696861) unfortunately yielded no results in our search. I recommend double-checking the serial number on the mounting bracket of the engine as well as inside the top cowling—this is typically where the most accurate identification plate or sticker will be found. Once the correct serial number is confirmed, it will be much easier to identify the exact year of your MerCruiser 3.0 (140 HP) and find the proper starter part number. If you have any additional questions or concerns, please feel free to reach out!
Best Regards Markine
MerCruiser 4.3L Alpha One engine and Alpha One Stern Drive (First Generation)
Engine Serial Number OC877169
I am searching for shop repair and maintenance manual.
I also have to identify the right parts catalog.
I am performing a complete restoration of a Wellcraft I96 Eclipse
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PartsVu replied:
Hi Domonic,
The MerCruiser 4.3L Alpha One engine with serial number OC877169 is a 1990 model year motor. Given the age of the engine and the specific parts and manuals you’re searching for, I recommend reaching out directly to MerCruiser or an authorized MerCruiser dealer. They can help you obtain the correct shop repair and maintenance manuals as well as the accurate parts catalog and part numbers needed for your complete restoration of the Wellcraft I96 Eclipse. If you need any further assistance, feel free to ask! Markine
Looking to get information s/n 0L0060333
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PartsVu replied:
Hi Matt,
Thanks for reaching out! Unfortunately, the serial number 0L0060333 didn’t yield any results in our system. I recommend verifying the serial number on the mounting bracket of the engine (usually near the transom clamp) and also inside the top cowling, as there may be another label or stamped plate there. Sometimes numbers can be misread or partially worn. Once you have the confirmed number, feel free to share it and we’ll be happy to look it up for you. If you have any other questions or concerns, please don’t hesitate to reach out!
Best Regards Markine
I am trying to figure out the gear ratio of my Alpha One sterndrive. The drive serial number is 0C475523, transom plate is 0C487278, and the engine is 0C388062 (5.7l).
Checking the original factory build sheet (if available), * Or manually verifying by rotating the input shaft and counting output revolutions. Let us know if you’d like guidance on how to do that, or if you have any other questions.Thanks for your help!
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PartsVu replied:
Hi, Thanks for providing the serial numbers. Based on your Alpha One sterndrive (drive serial number 0C475523) paired with a 5.7L engine, the most common factory gear ratio is 1.50:1. This ratio is typically used with V8 engines like your 5.7L. However, to be completely sure, the best way to confirm the exact gear ratio is by either:
Best regards,
Markine