Re: [Amel Yacht Owners] Yanmar 75HP - Cannot go over 2300 RPM



Thanks for your email. It is interesting.
I have my boat for one year.  The engine has more than 4,000 hours.  I don't know if bearings were replaced before. I greased prop bearings 2 times. Prop blades rotate freely. There is no play. There is no evidence of any bearing damage.  What else could go wrong? Did you feel anything wrong before you change the bears? Could you feel any difference in blade rotation after the bearings change?


On Jan 9, 2017 1:00 AM, "'sailormon' kimberlite@... [amelyachtowners]" <amelyachtowners@...> wrote:

I had the same problem with Kimberlite. Even though when I hauled her and tried to wiggle the blades of the autoprop they seemed normal. After exhausting all other possibilities , I spend a day and rebuilt the autoprop.

Voila back to 3500 rpm. I also rebuilt the prop at about 3500 hours.

The autoprop is a sensitive beast and the slightest out of balance will kill your rpm.

Fair Winds


Kimberlite Amel Super Maramu #376




From: []
Sent: Monday, January 09, 2017 12:18 AM
Subject: Re: [Amel Yacht Owners] Yanmar 75HP - Cannot go over 2300 RPM



Hi Vlad and Dominique,

AutoProps require regular maintenance.  If you haven't done that in a couple of years, that may be your problem.  There are some other threads on this forum that discuss this vis a vis low rpm.  Just spinning the blades on the hub doesn't tell you much.  They can feel perfectly free wheeling, and still be a problem.

If you don't run your engine hard on a regular basis, you can get a serious buildup of carbon in the turbo and exhaust elbow.  That's the second place to look.

Let us know what you find.



From: "Vladimir Sonsev sonsev52@... [amelyachtowners]" <>
Sent: Sunday, January 8, 2017 11:21 PM
Subject: Re: [Amel Yacht Owners] Yanmar 75HP - Cannot go over 2300 RPM



Hi Dominique,

I also have 75 HP YANMAR engine 4JH3-TE. I also can't develop more than 2200-2500 RPM.
I am discussing this problem with Autoprop.  I suspect that perhaps prop provides to much torque load.

Autoprop ask me for transmission gear ratio. The label on my transmission is gone. I requested this information from Amel. I am waiting for a reply now.

Autoprop also ask me to conduct some tests. I can't do the tests now because my boat is on hard.
I will keep you posted.



On Jan 8, 2017 10:26 PM, "songhui_ma@... [amelyachtowners]" <> wrote:


Happy New Year 2017


Yanmar 4JH3-TE - 3600 hours - 1500 hours maintenance. 


A New Zealand mechanic replaced the injectors with Yanmar ones I provided and sourced in the US [Niemiec] Both mechanic and my US provider confirmed that it was the correct part #. 


However and since I cannot go over 2300 RPM.

The smoke is pretty transparent neither black or white. 


I browsed the internet, got a lot of ideas, but nothing which jumped out.

I suspect it is related to the Turbo - over 2300 RPM - that I have not used much and realized I should have.   


Suggestions greatly appreciated




S/V Viva 

SM #374 

Opua, NZ 




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