Where Do I Find My Boat Engine Serial Numbers?

Where Do I Find My Boat Engine Serial Numbers?

Locating your boat engine’s serial number is crucial for maintenance and documentation. While these numbers are usually visible on the engine, factors like corrosion or missing stickers can make them challenging to find. This guide demystifies the process for various engine makes and models, offering a comprehensive list with illustrative photos to help you easily identify your engine’s serial number. Stay tuned as we continually update this resource with more engines and information.

The serial numbers in all our pictures below have been blurred intentionally.

Boat HIN Number Location

Found your engine serial number, but looking for your boat’s HIN number? We wrote an article on that here.

Petrol Inboards


There are a number of different locations you might find a Mercruiser engine serial number. These different locations are:

  1. On the stickers on the sides of the plastic cowling.
  2. Above the starter motor near the bellhousing.
  3. On the starboard side of the engine block, near the welsh plugs (if the engine has been replaced and has a remanufactured block).
  4. On the sticker on the heat exchanger (if it has a heat exchanger fitted).

You might find that on many model of boats, it’s best to get your phone on camera mode, with flash enabled, to identify the serial number. Engines are installed with tight tolerances and as a result, often don’t provide easy access to the side of the engine.

Mercruiser 4.3L serial number locations

Volvo Penta

The Volvo Penta petrol engines have the serial number located on the plastic cowling on top of the engine.


The Crusader Inboard serial numbers are usually located on a plaque on the starboard side of the sump.



Newer Cummins QSM/QSC model engines typically have a sticker fitted to the rocker cover. Older model Cummins (6BTA for instance) have a serial plaque fitted to the port side of the timing cover.


You will often find Caterpillar marine diesel serial numbers on the top of the rocker cover in the form of a small sticker.

Volvo Penta

These are typically located on the sticker on top of the plastic cowling, and a plaque on the port side near the sump line.


Looking for a Yanmar serial number? It’ll like be located on the top of the engine on a plaque, or on the cylinder head.


You’ll usually find Steyr diesel serial numbers on top of the engine near the emission control information sticker.


MAN marine diesel serial numbers are usually found on the port side of engine block, below exhaust manifold near engine mount. They are a black metal plaque attached to the engine.

Petrol Outboards


Locating the serial number on outboards is usually simple. On a Mercury outboard, you’ll usually have the serial number located on the starboard side of the swivel bracket, the mounting bracket or the cylinder head in sticker form.

Evinrude eTec

Another easy find – Evinrude eTec serial numbers are located on the port side of swivel bracket.


The Honda outboard serial numbers are usually found on the port side of the trim bracket.


You will typically find the Yamaha outboard serial numbers on the port side of the trim bracket.


Not sure where to find the serial number on a Suzuki outboard? It’s usually on the starboard side of the trim bracket.


For the most part, you’ll find Johnson outboard serial numbers on the port side of the trim bracket.

Petrol Generators


The Kohler generator serial numbers are usually found on top of electrical box.

Diesel Generators


The serial numbers on Onan generators are usually located on the port side of the front casing. On older model they can be found on top of the electrical box, or near the electrical windings in sticker form.


Your engine serial number will likely need to be identified when purchasing a boat, or ordering parts. I hope this article has helped you speed up the process of finding the serial.

Having trouble finding the serial number or would like the condition of the engine inspected? We can assist with a Pre-Purchase Survey and Mechanical Inspection in Sydney and Gold Coast region.

Are we missing a manufacturer’s serial number location? Feel free to email through with location and pictures to info@boatbuy.com.au.


What is the easiest way to find my boat engine’s serial number?

The simplest method is to check the manufacturer’s plate or plaque, typically affixed directly on the engine. This plate often contains essential information, including the serial number. Our guide provides detailed insights into the specific locations where each manufacturer usually places their identification plates, making it easier for you to pinpoint the exact spot.

How important is it to know my engine’s serial number?

Knowing the engine serial number is crucial for several reasons. It’s a key step in verifying the legitimacy of the boat during purchase to ensure it hasn’t been stolen. Additionally, it’s vital for financing and insurance purposes. When servicing your boat, the serial number enables you to access the correct parts diagrams, ensuring you order the right components for your specific engine model. Most financial institutions also require this information for processing.

What should I do if the serial number is not visible?

If the serial number isn’t immediately visible, start by checking all possible locations where it could be placed; some engines have dual serial number placements. In case both locations are missing, the serial number might be listed on the boat’s registration papers. As a last resort, if the serial number is still elusive, contact the dealer who originally sold the boat to trace its history and obtain the necessary information.

Can a boat engine have more than one serial number?

A boat engine should only have one unique serial number. This number is the engine’s unique identifier, ensuring that each engine can be individually tracked and serviced correctly. Multiple serial numbers on a single engine would be highly unusual and might warrant further investigation.

How does the serial number help in engine maintenance?

The serial number is indispensable for engine maintenance as it helps in accurately identifying the specific model and version of your engine. This precision is critical when ordering replacement parts or consulting maintenance manuals, ensuring that you receive the correct parts and information tailored to your engine’s exact specifications.

What are the differences in serial number locations between inboard and outboard engines?

In inboard engines, the serial number is commonly found on the top of the engine cowling or along the side of the engine block near the starter motor. For outboard engines, the serial number is typically located on the side of the bracket that secures the engine to the boat’s stern. These differing locations reflect the structural variances between inboard and outboard engines, necessitating a different approach when locating the serial number.

About the Author

Aaron O’Donoghue is a qualified Marine Surveyor & Engineer with nearly two decades of experience in the industry. He is an experienced boater from Sydney who grew up on the waters of Sydney Harbour. He left school at 15 to complete an apprenticeship as a Marine Mechanic. In 2015, he founded BoatBuy, where he has inspected thousands of boats and is passionate about helping others enjoy their time on the water. He has a wealth of knowledge and experience in the field. Do you have a boating related question? Feel free to reach out to me via email here.

Explore More

articles | 5 March 2024

How To Get Your Boat Surveyed

How to Get Your Boat Surveyed Whether you're in the market to buy or sell, a boat survey is likely an important step. It offers peace of mind to the buyer and ensures transparency for the seller. Let's dive into the process of arranging a boat survey, highlighting key steps...

articles | 3 March 2024

How Long Does a Boat Survey Take?

How Long Does a Boat Survey Take? Understanding the time commitment for a boat survey is an important question asked by buyers and sellers before a sale. Having inspected over 1,500 power boats across Sydney, Darwin, Gold Coast, and Melbourne since 2015, my experience offers insights into the duration of...

articles | 30 January 2024

A Professional Perspective on Pre-Purchase Oil Samples

A Professional Perspective on the Effectiveness of Pre-Purchase Oil Samples In my years of experience with marine mechanical diagnostics, I've frequently encountered a topic of debate: the effectiveness of pre-purchase oil samples. Having conducted over 600 oil analyses on boat engines, I've observed a pattern and wish to clarify some...