How do I find the serial number on Mercruiser inboard engines?

The serial number of a Mercruiser inboard engine or drive system is easy to find. The Mercruiser drive system consists of the engine, the transom plate (the through-hull fitting), and the Z-drive. All three components have their own serial number. If you are looking for a spare part for the Z-drive, we therefore need the serial number of the Z-drive, not the engine! This is something that many boat owners with a Mercruiser inboard engine are often not aware of.

The easiest place to find the serial numbers of your Mercruiser drive is on the engine. On Mercruiser engines from the mid-90s onwards, a sticker was placed on the engine cover or flame shield, on which all three serial numbers were printed.

In this image, you can see an older engine sticker at the top, on which the three Mercruiser serial numbers are printed: Engine Serial Number, Transom Serial Number and Drive Serial Number. The lower sticker comes from a newer engine, also with all three serial numbers of your Mercruiser drive.

In practice, we often find that either the sticker is missing or the numbers are no longer legible. Unfortunately, heat, oil/grease and cleaning agents make the numbers unreadable. But there are still other places where you can find the serial number of your Mercruiser drive.

Serial number of the Mercruiser engine

The image shows a plate on the engine block under "a", on which the serial number of the engine block is stamped. It is usually located on the engine block near the flywheel housing "b" or the starter "c". If this plate is not present, we will have to figure out which engine you have from the other numbers of the Mercruiser inboard engine. As a rule, we will then also need a few pictures of your engine

Serial number of the Mercruiser transom plate and Z-drive

Depending on the year of manufacture, you can find the serial number of your Mercruiser inboard engine's transom plate in many places. There are stickers on which the serial number was stamped, which are usually no longer legible after a few years.

 The images show the transom plates of newer Mercruiser engines. On the left, you can see the sticker of a transom plate of an AlphaOne Generation 2 drive. The lower image shows the cardan housing inside the engine compartment. In the image on the right, you can see a Bravo drive on which a plate is screwed on, which lists the serial number of the Z-drive and the gear ratio. On older Mercruiser Z-drives, you will find the number stamped into the band that is glued around the upper part of the Z-drive. 

In practice, we often find that the drive has been painted over with several layers of paint or antifouling, and thus the serial numbers are illegible. This is annoying and can only be removed mechanically with sandpaper in the right place.

If you still haven't found the serial number of your Mercruiser engine, you can also check your documents. As a rule, serial numbers are always recorded in bills of sale, insurance contracts or registrations with authorities.

We are happy to try and help you if you cannot find any serial number at all. In that case, it is best to send us pictures of the engine or spare part so that we can assess which engine you have! Please understand that the search may then take a little longer.