Where to Find the Serial Number of Your Boat Engine

Unless you are fortunate enough to own a newly purchased boat engine to purchase replacement parts or consumables such as filters or timing belts, you must first identify the engine.

Contrary to what many people think, not all are the same. A 1999 2-stroke Johnson engine is not identical to a 1993 25-horsepower Johnson engine, and even engines with the same horsepower that were manufactured in the same year may be different.

In this article, we will discuss how to identify each of the most popular boat engines on the market in the United States and what information can be derived from the series and model:

1. Johnson Evinrude

Johnson Evinrude engines are among the easiest to identify and among the most "generous" with information about characteristics.

Depending on the year of manufacture, the ID plate may look different and contain more or better information, but it always contains the model:

To identify Johnson Evinrude engines, we are only interested in the model stamped on this plate. Unless you are the lucky owner of a Johnson engine made in the 1960s (and that's possible because there are quite a few that still run "like new"), the model must look something like this: BE25RCOA. Using this example, we know that the engine is a 25hp string-start Evinrude made in Belgium in 1985.

To decipher the meaning behind the Johnson Evinrude engine model, here is a table:

Letters like "I," "K," or "M" mean you have a military model, a "living" piece of history on the boat. Finding parts for it, however, is nearly impossible. Johnson Evinrude has not published parts manuals for military models, and we can tell you from experience that the parts are not identical to the commercial or recreational versions.

2. Mercury Mariner

Mercury boat engines are some of the most popular in the United States.

When dealing with a used Mercury engine, always check to see if it has the series. If something goes wrong with a Mercury engine (and you're not lucky enough to have the OEM code stamped on the part) and you don't have the series or model, it's impossible to identify and almost impossible to buy parts that are compatible with it.

Usually, the Mercury and Mariner engine series can be found here:

If the ID plate is no longer there, then you may find it here:

Unfortunately, the Mercury or Mariner engine series doesn't tell us much about it; we can't figure out the year of manufacture based on the series, and no one can ever guarantee the compatibility of a part without the series.

If you are looking to buy parts for Mercury or Mariner boat engines, you need to remember that not all engines are the same. The year of manufacture doesn't matter; it is useful to know if it says Lightning or Super America on the engine, but without the series, no one can guarantee parts compatibility.

Another complicating feature of Mercury and Mariner engines is that they were manufactured at one time by Yamaha and Tohatsu, respectively, which means that these engines are Yamaha or Tohatsu and are only "branded" as Mercury. This in no way implies that all Mercury engines are made by anyone else. We mention this feature because it is possible to come across a Mercury without a series but visually recognize the parts as identical to a Yamaha or Tohatsu engine.

3. Yamaha

For the correct identification of Yamaha boat engines, we need 2 elements: the model and the code.

The ID plate should look like this:

Above we have the model "F15AEH," and the first rectangle below contains the code. To correctly identify the parts, we need both the series and the call sign, but usually only the call sign is enough.

When it comes to Yamaha boat engines, the country of manufacture is very relevant when buying parts. If it was made in Japan, then you are in luck, and you can find almost anything at acceptable prices. If it was made in France, then you have an engine from a fairly limited series, and it is very difficult to find parts for it.

4. Suzuki

Suzuki engines have the serial plate in the same place as Yamaha engines.

We can't decipher much from the series, but we can roughly tell what year the engine is from and what power it has.

5. Honda

Honda boat engine identification plate:

The series is indispensable when it comes to ordering parts.

6. Tohatsu

Tohatsu engines have an ID plate on the lower right side of the case.

To buy spare parts, you only need the model and year of manufacture.

7. Mercruiser

Inboard engines are the easiest to identify, but also the engines with the greatest variety of parts depending on the series. Despite the pervasive idea that all GM blocks are the same, we guarantee they are not.

MerCruiser engines have 3 identification series.

Depending on the generation, the ID plates are located in one of the places marked in the pictures above.

Newer generation engines have an ID plate that covers all three series:

8. Volvo Penta

To order spare parts for Volvo Penta boat engines, you don't necessarily need the series, just the manufacturer's model:

9. OMC

The OMC boat engines have the identification plate according to the picture below: