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

1. Where To Find The Serial Number Of
Your Boat Engine
Unless you are fortunate enough to own a newly purchased boat engine, in order 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 boat engines 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 engines.
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 engine series and
model:
1. Johnson Evinrude
Johnson Evinrude engines are among the easiest to identify and among the most "generous"
with information about engine characteristics.

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

3. 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 of your engine 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:

5. 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 engines 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 engines 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:

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

7. Unfortunately, the Mercury or Mariner engine series doesn't tell us much about the engine, 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 engine 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 really matter, it is useful to know
if it says Lightning or Super America on the engine, but without the engine 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 actually
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

8. 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
engine code.
The ID plate should look like this:

9. Above we have the engine model "F15AEH" and the first rectangle below contains the engine
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 the engine was made in Japan, then you are in luck and you can find almost
anything at acceptable prices. If the engine 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.

10. We can't decipher much from the series of Suzuki engines, but we can roughly tell what year the
engine is from and what power it has.
5. Honda

11. Honda boat engine identification plate:
The Honda engine 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.

12. To buy spare parts for Tohatsu engines, you only need the engine 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.

15. Depending on the engine 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:

16. 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:

17. Originally published at https://www.novesea.com/blog/post/where-to-find-the-
serial-number-of-your-boat-engine.html