Présentation

[Reyfromagde]

hi,
I just joint this forum, I am waiting my new Jeanneau CC9WA (called Leader in the USA) with twin 250HP and I’m located in the south of France.
I have read that the owners manual recommends a break-in procedure (what I fully agree with) but the dealer told me that he is asked by Yamaha to make trials at full power at the delivery in order to check the max rpm.
As I know what propeller to be used (Saltwater 17”) I do not agree with the dealer’s decision.
what is your opinion please?

[boscoe99]

All Yamaha motors are run at full power following their production in Japan.

Yamaha Japan wants each dealer that registers the motor to specify the RPM at which it ran at WOT on the boat on which it was installed. See below.

Many, many, many knowledgeable mechanics here in the USA do not agree with the Yamaha break in procedure that is written in the owner's manual. It may result in the motor taking a long period of time to break in. And before it can do so, many will experience the phenomenon known as "making" oil. Where gasoline gets into the oil system and dilutes the oil. Causes its level to rise.

Many believe their Yamaha motors will be better served if they are broken in using the Mercury Marine four stroke break in procedure.

[zenoahphobic]

I think the dilemma is that an engine that is new should be carefully treated and therefore "run in"; WOT is full power and therefore is logically perceived as not running in carefully.
However, it is the heat build up and subsequent expansion or distortion that one needs to be "careful" with, and that means limiting times run at considerable power so that limited heat is produced. We back down power to allow the engine to cool again; this being done a number of times until components have worn into themselves to a state where friction becomes stable with the designed lubrication.
To clarify, the making of oil is due to the piston rings not seating and not sealing properly. The consensus is that they need considerable "grinding " against the cylinder walls to achieve this good seal; that seems can only be done with considerable revolutions and power, the combustion charge helping with the expansion of the rings out against the cylinder walls.
If power and full revs are not used then this seating will take a long time. Hence fuel will seep past the rings diluting the oil raising its volume and causing possible damage as well as degrading the lubrication of the oil wearing the engine prematurely elsewhere; for too long. So Merc say a shorter and more vigorous break in.
I think you have to believe modern engines, and presumably Yamaha engines, are built with exacting tolerances and that can stand full power "out of the box", but perhaps like the OP, I do feel uneasy in flogging a new engine though.

[boscoe99]

I think you have to believe modern engines, and presumably Yamaha engines, are built with exacting tolerances and that can stand full power "out of the box", but perhaps like the OP, I do feel uneasy in flogging a new engine though.

Most of us coming from the automotive world (where motors run at maybe 20% of their rated power for the majority of their lives) would and do feel that running a motor at WOT is flogging it. If one considers a motor that is designed to run at 75% of its rated power for the vast vast majority of its life, then running it at WOT does not seem so onerous.

An outboard motor is more similar to a piston airplane motor than to an automotive motor with respect to the power settings that are typically used. Brand new piston airplane motors are operated at WOT during each and every take off. It does not hurt them. In fact, it is highly encouraged. Low power during the break in process is discouraged.

[Reyfromagde]

Thank you everybody for these interesting comments.
I have finally reached a Yamaha France engineer who has confirmed the procedure.

[99yam40]

Thank you everybody for these interesting comments.
I have finally reached a Yamaha France engineer who has confirmed the procedure.

was that that they conformed the need to run at WOT for the prop verification or the procedure for breaking in before running WOT

[boscoe99]

Yes, what is the procedure that you got confirmation of?

And when you refer to the "engineer", is that what is referred to as a mechanic here in the USA?

[Reyfromagde]

Yes he confirmed about the same procedure than mentioned on the above US sample.

[Reyfromagde]

This guy is engineer and he his the technical responsible who is the contact for the dealers/mechanics in case of technical problems (called ”technical inspector” ).

[boscoe99]

Did you ask him what he thought about the Yamaha break in procedure versus the Mercury Marine break in procedure?

[Reyfromagde]

No but honestly he did not seem to really agree with the Yamaha break-in procedure and he confirmed also that all engines are tested in factory without taking into consideration this procedure...
At the end I think that with the current thin fields of tolerances provided by the modern machining technology, the most important is to “feel” the machine and to avoid to “brutalize” any engine especially during the first hours.

[zenoahphobic]

Incidentally I just went to a boat show here in Melbourne Australia and at it was a very detailed cutaway Yamaha V8 425hp (greater horsepower spec in USA and some other countries).
I was surprised at how tiny the components generally were considering the sustained high revolutions and power output of this motor. Go's to show that modernisation involves making vital components smaller and lighter. One would hardly realise this without seeing all the internals of this otherwise enormous sized engine.

I wonder how this 5 litre plus engine compares to an equivalent automobile engine, as stated by Boscoe will run more hours at far greater revolutions and power than an automobile. This engine was quoted at A$67,000!

[almetelo]

What Mercury recomends as break in procedure?

[Reyfromagde]

On the French owner manual:
2 First hours: Variable rpm till 4500rpm (or 3/4 of max) and after: WOT 1mn each 10 mn, for the next 8 hours: avoid WOT more than 5mn

[boscoe99]

What Mercury recomends as break in procedure?

Here you are. As noted, Mercury specifies WOT operation for 12 minutes total time out of the first two hours. Yamaha specifies none.