Where is the serial number on a Mercury outboard?
For most Mercury outboard engines 8hp and higher, the serial number is located halfway down the transom bracket on the right (starboard) side, just below the powerhead. On 6hp and smaller engines, it's found on top of the swivel bracket.
Many boaters take a quick photo of their serial number with their phone—this simple habit can save hours of troubleshooting when ordering parts.
We highly recommend you take a picture of your ESN tag and keep the photo on your mobile phone in case the tag becomes unreadable or if you need this information when you’re not near your boat.
**Are you looking for Mercury Outboard parts and products for your specific engine? Check out PartsVu's Mercury Maintenance Parts Library. Common maintenance parts and products are presented by engine model allowing you to easily find the parts you need.**
What About a Mercruiser Serial Number?
On a Mercruiser sterndrive or inboard engine, typically, 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.
**Are you looking for Mercruiser parts and products for your specific engine? Check out PartsVu's Mercruiser category page. We've worked to make it as easy as possible to find the parts and products you need.**
Why Do You Need to Know Your Mercury Serial Number?

Simply put, your Mercury serial number will allow you to identify and order the right 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 Mercury serial number is the key.
As if matters weren’t confusing enough, sometimes Mercury will change an engine model design midway thru a given engine model year.
Therefore, Mercury Marine 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 Mercury engine schematic/Mercury outboard parts diagrams, the Mercury parts library, the complete list of Mercruiser parts library, or other resources.

How do I find out what year my Mercury outboard is by serial number?
To determine the year of your Mercury outboard, use the serial number on the engine and reference a Mercury Marine serial number-to-year chart. You can also enter the serial number into the Mercury Marine or PartsVu lookup tool to identify the exact year and model.
What is the serial number location on a Mercury 9.9 outboard?
The serial number for a 9.9hp Mercury outboard is usually located on the top of the swivel bracket, which may require tilting the motor to see clearly.
Where is the serial number on a Mercruiser engine?
It’s typically found near the starter or flywheel, or on the flame arrestor. Always take a photo of it for safekeeping.
How can I identify my Mercury outboard by serial number?
Use the serial number lookup on the PartsVu Mercury Maintenance Library or the Mercury Marine parts catalog to determine the engine model and year.
What year is my Mercury outboard motor?
Once you locate the serial number, compare it against Mercury’s official serial number/year chart, or enter it online in a lookup tool.
327 comments
Hi, I’m looking for any info on a Mercury serial number 4234337. I know it’s 85 Hp, and the casing says 850. I’m guessing it’s a 1975. Thank you
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PartsVu replied:
Hi Stephanie,
Thanks for reaching out! We looked into the serial number 4234337, but unfortunately, it didn’t yield any results in the system. To ensure accuracy, we recommend double-checking the serial number—it’s typically located on the mounting bracket of the engine and also sometimes inside the top cowling. If you’re unsure or having trouble locating it, feel free to send a picture of the serial number plate to partsvu@partsvu.com, and we’ll be happy to assist further.
Best regards, Markine
I inherited a mercury 25 hp outboard with the serial number A912282. Any chance you can help me with the year so I can get it running?
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PartsVu replied:
Hi Justin,
Thanks for reaching out! Based on the serial number A912282, your 25 HP Mercury outboard is a 1985 model. If you need help getting it running or finding parts, feel free to reach out—we’re happy to help!
Best regards, Markine
What year is my mercury 9396085 please and thank you
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PartsVu replied:
Hi Casey, Thanks for reaching out! Based on the number 9396085, it appears there’s a discrepancy with the typical year format, which makes it difficult to match it precisely in the system. However, the available information indicates that the motor was invoiced and registered in 1984. If you have any other details or need help with parts or service, feel free to reach out—we’re happy to assist further! Best regards,
Hi Matt,
Thanks for reaching out! Based on the serial number A152897, your Mercury 35hp outboard is a 1985 model. If you have any additional questions or need help with parts or maintenance, feel free to reach out
— happy to assist!
Markine
Hi Jesse,
Thanks for reaching out! I took a look at the serial numbers you mentioned:
O8174164 – This format doesn’t match Mercury’s serial system and didn’t yield any results. * OG174164 – Also didn’t return anything, possibly due to a misread character. However, 0G174164 (with a zero at the beginning) comes back as a 1994 Mercury 20hp MH model — which lines up with what the seller listed. If you have any additional questions or need help verifying parts or specs, feel free to reach out— happy to help! Markine