R 21 Yanmar 3YM30 rpm

R

Ron B

New member
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We have put about 50 hours on our recently acquired Martini R21 and have some conclusions and more questions.
We boat in a SE Florida canal system which is no wake to begin with. We have learned that we reach hull speed, 5.5 mph, at 15/ 1600 rpm and max cruising at about 2100[with too much wake]. The engine will top out at 3600, but wow what a wake!
In any event we love the quiet and smoothness at 1600.The economy is less than a quart an hour also!
I keep hearing a diesel must run at 80%of rated which is about 2800, which would get us arrested before we got out of our canal!
The question. Will the 3YM30 tolerate running at 1600 for an extended time? The engine has less than 300 hours. I understand a buildup of carbon can be expected in the exhaust elbow, but this is a minor problem.
Any advice would be appreciated Ron B Lighthouse Point Fl
 
Ron B-

I'm sure someone here has some experience with that engine. I know for sure that we have some who have had various types sizes, and makes of Diesels. I'm sure they will chime in.

However, the real sources of information on that particular engine would be the Yanmar technical representative from the U.S. Importer/Supplier and any local Yanmar dealers/repairers you can find. Have you tried these sources?

Good Luck!

Joe. :teeth :thup
 
I have had 3 Yanmar 3 cylinder diesels; 1 in a sloop and 2 in a catamaran, both sailing vessels. Probably over a thousand engine hours all together over about 8 years. In my opinion, running yours at 1600 rpm for long periods (read days on end non-stop) will absolutely do no harm assuming you have proper engine oil level, adequate air intake with clean air filter and a sound cooling system. I also think, after doing so, you find sea room to run the rpms up to the recommended 80 percent or higher for an hour or so while in gear, never in neutral.
Enjoy that sweet engine.

Aye.
 
No problem at the lower speed. Each time you take it out, find some place to take it up to 80% of WOT. Be sure that the water temp is up. The engine is Natural Aspiration, and will not have the problems the turbo engines will have at idling. I have run similar engines over a total of 7,000 hours at lower RPM, with no issues, as long as the temp is up, and you run it up regularly.

I also owned a generator with that same engine which was governed at 1800 RPM--the European version (50 hz) was governed at 1500 RPM- I put about 1500 hours on that engine. A friend of mine had the same generator, and put 25,000 hours on it before it was scrapped. He did two valve jobs in the 25,000 hours--and that was the only work except a couple of sets of injectors, a new injector pump and a bunch of impeller. As Foggy noted, this is one of the most common sail boat engines, and also it is used in thousands of generators (as it the similar sized Kabota)
 
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