What Is The Running-in Of An Outboard Motor, What Is It For, And Is It Necessary?

It is not enough to choose and buy an outboard motor, it still needs to be prepared for long-term operation. The fact is that the assembly of the PLM is carried out on a special conveyor, so it is impossible to accurately match the inner diameter of the cylinder with the outer diameter of the pistons, as well as the crankshaft bearings and gear gears. To avoid problems and even a quick failure of the outboard motor, do not neglect its running-in.

What Is The Running-in Of An Outboard Motor And What Is It Needed For?

The running-in of outboard motor is understood as the process of lapping motor parts. In addition to the mismatch of the cylinder diameters and the external piston rings, new parts may be rough and uneven. Such inaccuracies have a tolerance limit, especially in new models.

It is during the first launch that the parts are rubbed together. If the run-in is performed correctly, this guarantees the long-term operation of the motor without breakdowns, and its operation will be as efficient as possible. When the boat motor is run-in, all its moving components and parts are lubricated and lapped.

The following nodes must be run-in:

  • Crankshaft and bearings;
  • Piston rings and cylinders;
  • Gear gears.

During assembly, various parts are used (it depends on the manufacturer), taking on loads of different strengths and interacting with each other with different efforts. During the run-in, it is found out whether the parts fit well, how they interact and whether there are any deviations.

Is it possible to do without running-in?

Running-in can be compared to laying the foundation of a building: without it or with its poor quality, the construction will not last long. This is also the case with a boat motor: if this process is carried out incorrectly or ignored, it will reduce the service life of the product.

There are cases of motor failure due to the lack of running-in or improper conduct. Although in such cases, the issue of marriage is already being raised.

How To Perform A Run-in In General Terms

How to make a run-in yourself? The process itself takes about ten hours. Before running-in, you need to stock up on the necessary amount of gasoline. To do this, you need to know that an outboard motor with a power of 25 horsepower requires gasoline of 10 liters/h at maximum rpm. Low revs will take less fuel, but you should have at least sixty liters of gasoline with you.

Features that need to be taken into account:

  • It is necessary to carry out the run-in by placing the motor in water, for example-in a barrel with water, securely fixing;
  • The engine can smoke, which is not to be afraid of because the engine is a run-in with a large oil content;
  • A trickle of water must gush out of the water hole of the cooling system;
  • Turn on the speed should be on a small gas, otherwise, the engine may stall, and the key on the screws may be cut off.

Running-in Of A Four-stroke Engine:

  1. One tank of fuel should be developed at low or idle speed;
  2. Periodically, you need to change the speed (no more than 2.5 thousand revolutions per minute) with the flap half-open;
  3. At the second hour of running-in, the engine should be accelerated to 3 thousand revolutions per minute, the flap is open by 70%, it should be opened completely periodically;
  4. 8 hours at low or medium speed, only occasionally turning on full power.

A four-stroke engine requires an oil change in the crankcase. This action must be performed while the engine is still warm. If it has already cooled down, you should start it for a few minutes at idle.

After the engine is turned off, you need to remove the top cover. Pull out the device for determining the oil level, then unscrew the drain plug. This process will take about five minutes. Then the plug is screwed into place.


There is an opinion that running-in makes no sense and does not increase the wear resistance of boat engines in any way. But experts will never agree with such statements because this event allows you to correct small factory defects of the motor. Experience shows that products that have been run-in are less likely to break. Moreover, the process of running-in introduces the owner to the capabilities of the device. In any case, after buying a motor, it is too risky to go on a long trip right away, and running-in will extend the service life of the motor and help to unlock its potential.

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