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  1. #1
    Cadet
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    Default break-in and run new Mercury 4-stroke 115hp

    We have a new 115 hp, 4-stroke, Mercury outboard on our 24' Carolina Skiff. The manual doesn't have anything to say about break-in. The installer said to run it at varying speeds, but keep it below 3500 rpm for the first 4-1/2 hours of run-time. After break-in, cruise at 3500 rpm, but still vary the rpms periodically. I assume that means within a couple of hundred rpms either way, dropping back to 3500-3000 ever, say, 10 or 15 min.That is what I did with the 2-stroke we had. I don't know if 2-stroke and 4-stroke are different. I don't vary the highway speed of my pick-up, and no new cars have any break-in requirements.I am in no hurry to get anywhere, but others who use the boat say we should just ignore all that if it isn't in the manual. Should I just ignore break-in and ignore rpm variations?

  2. #2
    Admiral LubeDude's Avatar
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    Default Re: break-in and run new Mercury 4-stroke 115hp

    Id follow the dealers advice, if for nothing else, just to be able to say you did. The most important thing in my opinion would be to change the oil after the first 4-5 hours of operation to get the uglies out. Upper and lower.

  3. #3
    DJ
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    Default Re: break-in and run new Mercury 4-stroke 115hp

    DonHockaday,It's a totally different animal than a 2-stroke.Hower, think about how your car is broken in. The automaker ASSUMES that you are not going to climb a six percent grade at wide open throttle (without siopping) for the first few hours of operation. Although, it wouldn't hurt it. I know, I've simulated that on many a dyno.Operating under full throttle full load is probably not anticipated by the engine maker.Just drive it like you normally would.

  4. #4
    Ensign
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    Default Re: break-in and run new Mercury 4-stroke 115hp

    The Merc 115 4-stroke is basically made by Yamaha. It's the exact same engine as the Yamaha F115.From Yamaha's F115 Owner's Manual:"Break-in (running-in) time: 10 hoursRun the engine under load (in gear with a propeller installed) as follows:1) For the first hour of operation: Run the engine at 2,000 r/min or at approximately half throttle.2) For the second hour of operation: Run the engine at 3,000 r/min or at approximately three-quarter throttle, and during this period run it at full throttle for approximately one minute every ten minutes.3) For the next eight hours of operation: Avoid continuous operation at full throttle for more than five minutes at a time.4) After these first 10 hours: Operate the engine normally."

  5. #5
    Senior Chief Petty Officer
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    Default Re: break-in and run new Mercury 4-stroke 115hp

    Yes, and after 10 hour break in on a Yamaha F115 4-stroke You must service the outboard at a (Yamaha in my case) service center (change oil etc). It is a must (at least in my country) for warranty to be valid to do that 10 hour service. I have a Yamaha F115 that I bought new last Year and I made the break in according to the Owners manual. I do not know if it is same for Mercury 115 EFI 4-stroke./Bo

  6. #6
    Cadet
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    Default Re: break-in and run new Mercury 4-stroke 115hp

    Thank you all very much for the input. Apparently, varying the rpms during the early break-in period was not recommended. 1) After the break-in period, does it hurt the motor to run at the same rpm for a half-hour or hour at a time?2) Does it hurt the motor to run it at max rpm for more than a few minutes at a time?Some people who use the boat want to get where they are going as quickly as possible (or just like to feel wind in their eyes?). I think it is rediculous to try to shave 5 minutes off a 40 min trip, but it seems to be important to others.Thanks,

  7. #7
    Admiral LubeDude's Avatar
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    Default Re: break-in and run new Mercury 4-stroke 115hp

    I would break the engine in right, even if I had to do it myself. I have heard that the four strokes, unlike 2 strokes, really are not designed to run WOT for extended periods, What I heard might not be right as I cannot say where I heard it and do not know the validity of that statement, however I beleive it to be true. What say Rodbolt to that statement?

  8. #8
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    Default Re: break-in and run new Mercury 4-stroke 115hp

    Apparently, varying the rpms during the early break-in period was not recommended.
    Yes it was. "2) For the second hour of operation: Run the engine at 3,000 r/min or at approximately three-quarter throttle, and during this period run it at full throttle for approximately one minute every ten minutes.3) For the next eight hours of operation: Avoid continuous operation at full throttle for more than five minutes at a time."
    1) After the break-in period, does it hurt the motor to run at the same rpm for a half-hour or hour at a time?
    No. "4) After these first 10 hours: Operate the engine normally."
    2) Does it hurt the motor to run it at max rpm for more than a few minutes at a time?
    No.4-stroke outboards are designed to run at WOT, or constant throttle for hours on end.

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