Breaking in a new four stroke 90

[davidglow12]

I just got a new mercury four stroke 90hp and I am in the break in process. What is the best way to break it in and get optimum performance out of the motor? I have heard things like running it for X amount of rpms for X amount of time then let off and do it again at certain intervals. Any advice would be awesome thank you.

[Wildcat Dude]

Didn't you get your owners manual? Its detailed in that.

[EuropeanAM]

Always consult your Engine Owner's Manual for proper break-in recommendations.

Per your engine's Owner's Manual:

Engine Break‑in Procedure:


IMPORTANT: Failure to follow the engine break‑in procedures can result in poor performance throughout the life of the engine and can cause engine damage. Always follow break‑in procedures.


For the first two hours of operation, run the engine at varied throttle settings up to 4500 RPM or at three‑quarter throttle, and at full throttle for approximately one minute every ten minutes.

.For the next eight hours of operation, avoid continuous operation at full throttle for more than five minutes at a time.

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In addition to the above, I would also recommend that you complete at least TWO (2) "Heat Cycles" during the first THREE (3) hours of operation.

A "Heat Cycle" consists of warming the engine up to operating temperature, making a run, returning to idle, shutting the engine down, and letting the engine COMPLETELY cool down to ambient temperature.

This can be accomplished while you fish, with separate days of running, etc.

[Boatman Mike]

I recently purchased a 115 HP Mercury 4 stroke and the owners manual is a little cryptic. The concensus seems to be 20 hours or 3 months, whichever happens first. My dealer says 10 hours. Good luck, Mike

[Wildcat Dude]

You're talking about the first maintenance - this is about break in which seems very clear to me. Welcome to the BBC by the way.

[dockman]

My buddie just bought a 115. Dealer said not to exceed 3500 Rpms for 18 hours? This is different from the manual. Is he just being more conservative? Will not taking to full throttle one minute every 10 per the manual hurt any thing? He said they will do a run time scan at the 29 hour service.
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In addition to the above, I would also recommend that you complete at least TWO (2) "Heat Cycles" during the first THREE (3) hours of operation.

A "Heat Cycle" consists of warming the engine up to operating temperature, making a run, returning to idle, shutting the engine down, and letting the engine COMPLETELY cool down to ambient temperature.

This can be accomplished while you fish, with separate days of running, etc.

[dockman]

Correction 20 hour service. Fat thumbs.

[EuropeanAM]

My buddie just bought a 115. Dealer said not to exceed 3500 Rpms for 18 hours? This is different from the manual. Is he just being more conservative? Will not taking to full throttle one minute every 10 per the manual hurt any thing? He said they will do a run time scan at the 29 hour service.

FOLLOW THE INSTRUCTIONS IN YOUR ENGINE OWNER'S MANUAL.

What you were "told" could potentially result in an engine that does not properly seal piston rings, and other components may not "run-in" as designed.

If the dealer DID actually make that comment- FIND ANOTHER DEALER.