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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3383
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 2011 Yamaha 4 stroke 150 horse 100 hours on it starts

Customer Question

I have a 2011 Yamaha 4 stroke 150 horse 100 hours on it starts fine runs great until I put it in gear and then it becomes just a little rough give it more gas runs fine but really don't like the vibration and rough idle when cruising canals..Can you help
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.
Hello, my name is***** will be assisting you today. You didn't mention if the engine has always done this or just started recently. If it is recent, has anything at all changed on the engine?
Customer: replied 1 year ago.
No nothing has changed it started at the end of last year
Expert:  Charles replied 1 year ago.
Was there a slight impact with the bottom or a log?Or a new prop installed?Have you owned the engine since new?
Customer: replied 1 year ago.
No new prop it actually looks fine and isn't bent the vibration come from a idel when I'm going really slow
Customer: replied 1 year ago.
As soon as I give it gas it goes away
Customer: replied 1 year ago.
So it an rough idel at idel speed
Expert:  Charles replied 1 year ago.
I understand. There is an issue that most four stroke engines have and that is clutch rattle. This happens normally when just in gear and the engine, although it looks like it is running a constant RPM is actually not. It is surging and stalling, as the flywheel speeds up and down, so does the drive shaft. This en-turn also speeds up the pinion gear. The weight of the prop will keep it turning at a fairly smooth speed, yet as the flywheel speds up ans slows down, you get clutch rattle. This is a normal occurrence for these engines. The way to combat this is to get a prop hub that will adsorb the rattle. Does all that make sense?
Customer: replied 1 year ago.
Yes and no It hasn't had this issue in the past so it seems like I can be fixed without a prop hub but I will look into it
Expert:  Charles replied 1 year ago.
Also if the engine idle RPM has slowed by just 50, that can also do it. Make sure that the prop is still really tight on the shaft as well.
Customer: replied 1 year ago.
I could sent you s video of it tomorrow?
Expert:  Charles replied 1 year ago.
Sure. Can you upload it here or to a site like youtube and then just send me the link.
Customer: replied 1 year ago.
Will do for sure
Expert:  Charles replied 1 year ago.
Sounds great. I will look for it.
Customer: replied 1 year ago.
I will send you the video this week, Sorry its taken me so long the weather has been awful
Expert:  Charles replied 1 year ago.
No worries. There are no time limits here.

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