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Old 30 March 2023, 18:05   #1
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Mercury Optimax

Hi all,
Pretty new to the forum and hopefully i have posted this right !! I have a Mercury Optimax 115hp on my rib and it has started to make a funny noise when i am dropping the throttle off. Accelerating etc are all fine but when i drop off there is like a whine or something almost like the sound of a belt slipping or something. I would be very grateful if anyone could offer any advice as to what they think it might be.
Thanks in advance
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Old 30 March 2023, 18:16   #2
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Do these engines not have an alternator belt? Unusual for a belt to slip on the overrun and not under acceleration.
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Old 30 March 2023, 18:48   #3
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It does yes i believe but i do not think that is the cause. I do have a short video of it but am struggling to find a way of uploading it. Not very tech savvy
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Old 30 March 2023, 19:18   #4
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Stick the video on You Tube and then link to it.

Pete
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Old 30 March 2023, 19:35   #5
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https://youtu.be/TSqjJNgd28g

Hopefully this works. Thanks
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Old 30 March 2023, 19:40   #6
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Quote:
Originally Posted by carrich9073 View Post
https://youtu.be/TSqjJNgd28g

Hopefully this works. Thanks
Video is “private”..
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Old 30 March 2023, 19:50   #7
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Sorry. Hopefully sorted now
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Old 30 March 2023, 20:22   #8
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Sounds like turbo flutter from an old school rally car.

Did it just appear one day? Is it getting worse?
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Old 30 March 2023, 20:28   #9
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Yes. Just appeared on first trip out last year. Didn't appear to get any worse, just pretty annoying noise. It does sound a bit like that without the air dump.
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Old 30 March 2023, 21:02   #10
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If it were me I’d stick a bit of belt dressing on the belt then let it develop.
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Old 30 March 2023, 21:14   #11
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I had one of these engines before. Very good motor. Fuel efficient and powerful!

I'm pretty sure it has a belt-drive compressor to be able to deliver compressed air into the fuel rail and then mixed fuel and air into the combustion chamber. Anyway, I would check the belt at the top of the engine. There is a cover that pops off. That belt needs to be in great shape. Also check any hoses going from the compressor.
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Old 04 April 2023, 18:09   #12
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Video is “private”..
The rest of us watched it...it's you...your on youtubes naughty list
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Old 05 April 2023, 16:53   #13
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I had one of these engines before. Very good motor. Fuel efficient and powerful!

I'm pretty sure it has a belt-drive compressor to be able to deliver compressed air into the fuel rail and then mixed fuel and air into the combustion chamber. Anyway, I would check the belt at the top of the engine. There is a cover that pops off. That belt needs to be in great shape. Also check any hoses going from the compressor.
Agree with this.
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