Time spent breaking in your outboard motor is the most critical time for your engine. If you do not break in the motor correctly, you will have issues with horsepower output, seals leaking and eventually premature engine failure. The process for breaking in an outboard motor like the Tohatsu four-stroke or the Mercury four-stroke vary slightly from the lower horsepower engines to the larger horsepower engines, but the overall concept is largely the same.
Turn the outboard motor on for a period of 10 minutes and allow it to idle. This circulates oil through the engine and ensures every moving component has oil on it. You can idle the engine while the boat is on the trailer or on the water.
Run the engine at half throttle for two hours at approximately 3,000 rpm. You can do this with the boat on the trailer or in the water. You do not have to complete the full time at one sitting.
Run the motor for one hour between half throttle and three quarters throttle with a one-minute long, full-throttle run every 10 minutes. You can complete this step with the boat on the trailer or in the water. You do not have to complete this at one sitting.
Run the boat for seven hours at three quarters throttle with a two-minute long, full-throttle run every 10 minutes. Complete this step with the boat in the water. You do not have to complete the full seven hours at one time. You can complete this task over time.
Run the engine as normal once you pass a total of 10 hours break-in time, excluding the first 10 minutes at idle.
