Outboard Motor Serial Numbers: Reading the Bracket Label and Block Number

An outboard is built to come off the boat, which is exactly what makes it easy to steal. A couple of clamp screws and a trailer parked in the driveway is all a thief needs, and a motor worth several thousand dollars can be listed online within days. Generators, mowers and pressure washers have the same problem: portable, valuable and hard to tell apart from every other unit of the same model.

The serial number is what makes your engine yours. Police need it to identify recovered property, insurers ask for it on a claim, and as a buyer it is the quickest way to find out whether a second-hand motor has a history the seller isn't mentioning.

Two numbers, not one

Most outboards carry identification in more than one place, and it's worth knowing both.

• The ID label on the bracket. The main identification label sits on the mounting hardware that attaches the motor to the transom, usually the clamp bracket or swivel bracket, near the swivel tube. On modern motors it is normally a tough sticker rather than a riveted metal plate, and it carries the model code and serial number.
• The number on the powerhead. Many outboards also carry the serial on the engine itself. Depending on the brand and age, that may be a small round decal on the block, a number stamped on a metal core plug (often called a welsh or freeze plug), or digits stamped directly into the casting. You'll usually need to take the cowling off to see it.

Why both matter: the bracket and the powerhead are separate assemblies. A label can be peeled off, painted over or swapped along with a bracket, but a number on the block is much harder to change. If you're buying, the two should agree. If you're an owner, photograph both.

Where the major brands put it

Yamaha

Yamaha calls the serial the Primary Identification Number (PID). It's printed on a rectangular label on the port side of the mounting bracket, with the model name in the top field. The production date is on a separate label on the starboard side of the bracket. Some Yamaha motors also have a small round decal on the powerhead carrying the serial.

Mercury

Mercury's serial number tag is on the swivel bracket. On larger motors look on the starboard side, partway down the transom assembly just below the powerhead; on small portables it's typically on top of the swivel bracket. Some Mercury motors also carry the serial stamped on a plug or directly on the block.

Suzuki, Honda, Tohatsu and others

Layouts vary by model and year, but the same rule applies: start with the clamp and swivel brackets, then look on the powerhead under the cowling. Your owner's manual will show the exact spot, and most manufacturers' websites have a serial number locator. If you still can't find it, a dealer for that brand will know where to look.

Generators, mowers and pressure washers

Small petrol equipment often has two separate numbers: one for the engine and one for the machine it's bolted into.

• Generators. Look for a label on the frame or a lower corner of a side panel. Honda's EU2200i, for example, has its frame serial number on a label near the bottom of one side panel, separate from the engine number.
• Lawn mowers. The mower's own model and serial label is usually on the deck or the air cleaner housing. Briggs & Stratton stamp the engine's model, type and code numbers into the engine itself, commonly on the blower housing, above the spark plug or near the muffler.
• Pressure washers and other engine-driven gear. Check the frame or pump for the machine's label, then the engine. Honda stamps its engine serial numbers on the crankcase; on many GX engines it's on the side of the block under the fuel tank.

Generators and petrol tools are a regular target in thefts from utes, trailers, sheds and building sites, so tradies should record these numbers along with their power tools. Our guide to protecting power tools from theft covers securing the ute and job site.

Does boat registration record the engine?

It depends on the state, so check with your state's maritime authority rather than assuming. In NSW, for example, the vessel registration application asks for engine details, including each engine's serial number. Registration also records the boat's Hull Identification Number (HIN), but the HIN identifies the hull, not the motor. Swap the outboard and the HIN stays the same. If your state records engine details, update them when you change motors, so the registration matches what's actually on the transom.

Also worth knowing: a PPSR search on a boat is done by its HIN, but an outboard on its own is generally not treated as "watercraft" under the Personal Property Securities Act and can't be searched by its serial number. Any finance owing on a standalone motor would be registered against the owner's name instead.

Making your outboard harder to steal

• Fit an outboard lock. A lock that covers the clamp screws stops the motor being wound off in a minute. Add a hitch lock or wheel clamp to the trailer so the whole rig can't be towed away.
• Mark it. Engrave your driver's licence number or another identifier on the bracket and inside the cowling. Engraving won't stop a determined thief, but it makes the motor harder to sell and easier for police to return. Some police stations lend engravers free of charge.
• Photograph everything. Take clear photos of the bracket label, the powerhead number, the whole motor and any scratches or repairs. Keep the receipt and service records with them.
• Store it out of sight. A boat in a locked garage, or at least covered and behind a gate, is a far less tempting target than one on the nature strip.

Checking a second-hand outboard before you buy

1. Get the serial number before you drive out. Run it through the SerialCheck search to see whether it's been reported stolen. A genuine seller has no reason to refuse.
2. Inspect the bracket label. Be wary if it's missing, has blade or screwdriver marks around it, sits under fresh paint, or is buried in grease. Labels do wear, but a damaged one needs a believable explanation.
3. Compare it with the powerhead. Ask for the cowling to come off and check the number on the block against the label. A replacement powerhead can legitimately carry a different number, but the seller should have the invoice to prove it.
4. Ask for the paperwork. Service records, the original receipt and a registration certificate that lists the engine all help. A dealer for that brand can often confirm the model and year from the serial, and may be able to tell you whether it's been serviced through their network.
5. Trust the warning signs. A price well under market, a motor sold separately from a boat the seller can't show you, a seller who wants to meet in a car park, or pressure to pay before inspecting are all reasons to pass. Our guide to buying safely on Marketplace and Gumtree covers the rest.

If the motor turns out to be stolen, you can lose both the motor and the money you paid, even if you bought it in good faith. We explain why in why you should always check the serial number before buying second-hand.

If your outboard or engine is stolen

Report it to police as soon as you notice, with the make, model, serial numbers from both the bracket and the powerhead, your photos and any engraved markings. Tell your insurer and your state's maritime authority if the motor was listed on your boat's registration. Then mark it stolen on SerialCheck so anyone who checks the serial before buying is warned. Our step-by-step guide on what to do if your property is stolen walks through police reports and insurance claims in detail.

Before the boating season

Pull the cowling, photograph both numbers and write them down while the motor is still in your shed. Then register your outboard on SerialCheck so the motor can be traced back to you from either number. For bikes, phones, tools and everything else, see our guide to where to find serial numbers on common items.