Johnson and Evinrude outboards, use the model number, rather than the serial number, to determine the year model. Mercury outboards, uses serial number and horsepower.
Mercury Marine uses both the serial number, and the horsepower rating, to determine the year model of their outboards.
In addition to the serial number, which is listed here, the horsepower of the engine is needed, to determine the year model of Mercury outboards.
The "OC" model 75 hp Mercury outboards were manufactured in 1990.
In order to answer this question, the horsepower rating of the motor has to be known. Mercury outboards use the serial number, and horsepower, to determine year model.
To determine the age of a 20 hp Mercury Thunderbolt with the serial number 7139300, you would typically need to consult the manufacturer's production records or a reference guide specific to Mercury outboards. However, Mercury outboards from that era have serial numbers that can often be decoded to find the year of manufacture. Without access to specific databases or records, it's difficult to provide an exact age, but generally, Mercury outboards from that range were produced in the late 1970s to early 1980s.
Go to Marine Engine.com and click merc outboards then click mercs by serial number....al
The older model mercury outboards, with maker points, should have a 0.020" gap setting.
The "OC" model 75 hp Mercury outboards were manufactured in 1990.
The serial number OC111635 indicates that the 15 HP Mercury outboard was manufactured in 2000. Mercury outboards use a serial number system where the letter prefix often denotes the year of production. In this case, the "O" in the serial number corresponds to the year 2000.
The serial number and horsepower rating for the engine is compared to the Mercury outboard model year chart.
This question cannot be answered with a serial number alone. Mercury outboards determine year model by comparing the serial number, in a selected horsepower range, to a range of serial numbers, produced within each year of production.