Hi Mark, just to add to the ideas. I have spent many years around diesel engines in a variety of applications. A regular maintenance need is injector servicing and a dark smoky exhaust is one indicator that it is time for that service. Fuel is driven through the injectors into the combustion chamber at very high pressure though a small nozzle. Over time this nozzle wears and increases in diameter leading to over fueling and a smoky exhaust, particularly under load.
I would expect a performance decrease as well as the smoke. Injector servincing is not a big deal. You need a competent tradesman with the right tools to remove them and a specialist service centre to sevice them..
Regards
Danny
SM 299
Ocean Pearl (NZ)  

--- On Thu, 31/3/11, Mark <markghayden@...> wrote:


From: Mark <markghayden@...>
Subject: Re: [Amel] SM2K Yanmar RPM
To: amelyachtowners@...
Date: Thursday, 31, March, 2011, 8:17 PM


 



Thanks for the info. I'm current with all the filters, etc. The fact that my RPM's are within the same ballpark as when the previous owner acquired the boat from Amel is consistent with that.

Are my RPM's in line with what I should be expecting? Or is there something about the application that makes the RPM's I'm getting OK. If my RPM's are as expected, I'd think there would be other owners who had been told the same thing as me.

BTW, how can you tell if the autoprop reaches full pitch?

Thanks in advance, Mark

--- In amelyachtowners@..., Richard03801 <richard03801@> wrote:

Do you have clean fuel and Air filters / cleaners is the prop clean and does it reach full pitch. Are you getting over heating when when you run it hard is the Saltwater heat exchange clear. And are the fans running w/fresh air. Last is the turbo carbined up. All these will cause rpm loss. It is not an easy item to solve. We never run wide open a diesel likes a load it does not need to go full bore all the time.

Regards
Richard Piller

On Mar 29, 2011, at 19:10, "Mark" <markghayden@> wrote:

We have a SM2K with an Autoprop. We have been getting somewhat dark exhaust from our engine so we've had a Yanmar serviceman look at it. The Yanmar 4JH3-TE engine is rated at 3800 RPM. When testing the boat on calm water (clean hull, clean prop...), we could got 3100 max RPM, similar to when I purchased the boat. Referring to the maintenance log, the original owner got 3250 max RPM when he tested it around the time of purchase from Amel.

The Yanmar guy I am working with tells me this RPM is an indication the engine is overloaded and is a likely cause for the exhaust. He went further and says that Yanmar would not warranty the engine in this application, given the load, gearing ratio, propeller combination prevents it from reaching the spec'd RPM. The implication being it is a flawed design, which I find hard to believe.

I contacted Amel several months ago about this and didn't get a response. Has anyone been told this before? Is there an explanation for the design?

Thanks in advance,

Mark

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