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How to Tell Us What We Are Working On

Let's talk about boat motor identification.

When dealing with boat motor and drive systems, be it outboard, inboard, or sterndrive, there are many different identifiers that are helpful and a lot of times, necessary to get you the parts and service that you need. Having the model and serial number is a surefire way to make sure you get the parts and service needed to get you back on the water as quickly as possible!


So, let's start with the outboards:

For Mercury: Facing the motor from the propeller, look on the right side of the swivel bracket ( the part that allows the motor to swing). There will be a sticker that gives the model number, serial number, and the year model on most motors. The model and serial in conjunction are particularly helpful when dealing with Mercury outboards.

For Johnson/ Evinrude: These motors have their ID tag on the swivel bracket on the left side of the motor when facing it from the propeller. This tag gives you the model and serial numbers, but not the manufacture date. Alternatively, as the sun or age can wear these numbers off of the tag or make them unreadable, the model number can found on the freeze plugs, unless the freeze plugs have been replaced with aftermarket type plugs. The model number of these motors is the most important defining number.

For Yamaha: The tag on a Yamaha outboard will typically be on the clamp bracket at the upper portion, near the steering tube. It will have the model number on it.

For Chrysler/ Force: The early models of these had a metal ID tag under the cowling (motor cover) on the front of the splash pan (lower cowling). It is in front of and below the air breather. For later Force models (those made under the US Marine tag) the identification tag will be on the left side of the clamp bracket. For the Force models produced by Mercury, the tag will be located as the Mercury, already mentioned above.


Now, on to the Sterndrives. Wtih the Sterndrive system being made up of 3 different units (engine, transom, and outdrive), there are separate identifiers for all three components. Fortunately, the outdrive and transom tags are far more similar than the outboards, in regards to their locations.

For Outdrive Identification: The numbers will either be on a plate at the very top of the outdrive or stamped into the side on the upper portion.

For Transom Assemblies: These numbers will be imprinted on the assembly at the upper portion either directly into the unit or on a tag in the same location.

Engines- Sterndrive and Inboard

For Engines: This is where things get a bit more different from one another.

For most all marine engines the most basic of information can be found right on top of the air breather cover (flame arrestor) or its plastic, decorative cover. This, at minimum, indicates the displacement size of the engine. Sometimes this will include a few identifying letters (such as a 5.7GX in a Volvo Penta identifying it as a 5.7 liter V8 with Throttle Body Injection). When those numbers don't give enough information, the Serial number can be found as follows:

Mercruiser: On Mercruiser engines, the identification can be found

Volvo Penta: Early Volvo Penta Engines had a tag on both the engine block and the exhaust riser. This was usually a stainless steel tag, sometimes brass. This tag has the engine serial number which relays most all pertinent information. Later models (starting with the SX models) there is/ was a tag on the bracket that holds the main power breaker on the front of the engine at the top.

OMC: Older OMC Sterndrive engines had a tag on the valve cover with the important info. Unfortunately, as time passes these can sometimes fade or be painted over altogether. Sometimes a bit of acetone will remove enough paint to see the numbers.

Newer OMC engines had their tag on the exhaust riser. Unfortunately, risers are replaced with some amount of frequency and may not have the original tag on them

Yamaha: There is a stainless steel, printed and imprinted tag on the rear Port side (right when facing the pulleys) toward the lower portion of the block. This is directly in front of the flywheel cover.

Indmar: For Indmar engines, there is an identification tag with all of the important information, including transmission identification located on the oil pan. This is a printed sticker that does hold up fairly well against the elements and deposits.

PCM: Similar to Indmar, these are tagged on the oil pan.

So there it all is, and we hope it helps you identify your Motor, Sterndrive Unit, or Transom Assembly. And if there is eveer any question or doubt, just give us a call at 713-941-4303, an email at, send us a message via this website, or shoot us a message through our Facebook Page @munsonmarinehtx.

Thanks for reading and we hope to hear from you soon!!

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