Hello, I have a 95 Hunter 336 with a Yanmar 3GM30F. I have had the boat for a year and this has been my first experience with a Diesel. I have a few questions. 1. Are there recommended cruising speeds (RPM)? 2. Is is ok to idle the engine to charge the batteries? Is yes, is there a recommended RPM for this? 3. Is it ok to run engine at same RPM for extended periods of time when cruising (no wind spells)? 4. What is recommended for fuel additive: during season and for winter storage (cold winters here in Boston area)? 5. Other than owner's manual, is there a better guide for operation and maintenance of the engine? Where available? 6. Is it a good idea to increase RPM just before cutting the fuel to turn it off? Apologies for a few of these questions being repeats of some I have seen on the HOW site but often the responses are conflicting and I am looking for clear advice. thank you, Bob
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Ron Dague
Here's My Engine Maintenance
I'm sure Gordon or someone more experienced will also reply, but I'll give your questions a shot: 1. I believe that your engine has a maximum speed of around 3400 rpm. 80% of that is the maximum that you should cruise at for extended periods. That's about 2850, or so. 2. Idling a diesel engine, like those on your boat is not ideal, even for battery charging. Although occassionally doing so will do no damage, the engine will "carbon up" more and is best run under load, say when cruising. So if you need to charge when on the hook, do so, but keep it at a minimum. Get a decent charger for charging at the dock, and/or upgrade your alternator for quicker charging when away. 3. You can run your diesel all day, if needed, when cruising. In fact, running it for longer periods is better for the engine than short runs, where it never fully warms up. With proper maintenance, oil changes, filter changes, etc., it should last 10,000 hours. Of course don't use it if you are heeled excessively. Probably not at more than 20 degrees, definately not more than 30 degrees. (But then, Why would you, if heeled, there must be wind!) 4. Additives are controversial. Clean fuel in the first place, is the "best additive". Your first filter, probably Racor, should also have a water extractor, so you shouldn't need any "gasline antifreeze" type of additive. Of course, also check the O-ring on your fill tube at the deck for, (as Gordon has told us!) it is the most common place for water to enter the system. Many people add a biocide to their tanks. If so, only add recommended amount. If you keep the water out, it isn't necessary, since the algae grows in the water, not the diesel fuel. No other additive are needed nor desirable. 5. The shop manual from Yanmar is a valuble resource. Lots of info, and you can order it from Torreson's, that hosts this thread. The Seloc manual, available from bookstores, including Amazon.com (and the HOW Store?) is useful, but not as engine specific as the Yanmar manual. 6. NO! A diesel is stopped by cutting off the fuel supply. That's what pulling that knob at the engine panel does. So increasing RPM right before cutting off the fuel is counterproductive. It doesn't accomplish anything. There, you have my answers, and I'll await for any fine tuning (or outright rejection by Gordon and other's more experienced than I am).
I'm sure Gordon or someone more experienced will also reply, but I'll give your questions a shot: 1. I believe that your engine has a maximum speed of around 3400 rpm. 80% of that is the maximum that you should cruise at for extended periods. That's about 2850, or so. 2. Idling a diesel engine, like those on your boat is not ideal, even for battery charging. Although occassionally doing so will do no damage, the engine will "carbon up" more and is best run under load, say when cruising. So if you need to charge when on the hook, do so, but keep it at a minimum. Get a decent charger for charging at the dock, and/or upgrade your alternator for quicker charging when away. 3. You can run your diesel all day, if needed, when cruising. In fact, running it for longer periods is better for the engine than short runs, where it never fully warms up. With proper maintenance, oil changes, filter changes, etc., it should last 10,000 hours. Of course don't use it if you are heeled excessively. Probably not at more than 20 degrees, definately not more than 30 degrees. (But then, Why would you, if heeled, there must be wind!) 4. Additives are controversial. Clean fuel in the first place, is the "best additive". Your first filter, probably Racor, should also have a water extractor, so you shouldn't need any "gasline antifreeze" type of additive. Of course, also check the O-ring on your fill tube at the deck for, (as Gordon has told us!) it is the most common place for water to enter the system. Many people add a biocide to their tanks. If so, only add recommended amount. If you keep the water out, it isn't necessary, since the algae grows in the water, not the diesel fuel. No other additive are needed nor desirable. 5. The shop manual from Yanmar is a valuble resource. Lots of info, and you can order it from Torreson's, that hosts this thread. The Seloc manual, available from bookstores, including Amazon.com (and the HOW Store?) is useful, but not as engine specific as the Yanmar manual. 6. NO! A diesel is stopped by cutting off the fuel supply. That's what pulling that knob at the engine panel does. So increasing RPM right before cutting off the fuel is counterproductive. It doesn't accomplish anything. There, you have my answers, and I'll await for any fine tuning (or outright rejection by Gordon and other's more experienced than I am).
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Gordon Torresen
Good grades for Ron Dague
There are only two changes that I would make to Ron Dague's treatise. The first would be to expand the answer to question two. You would want to bring your RPM up to about 1500 to assure that the alternator is putting out full amperage. Second, I would spell Torresen differently. Well done, Ron.
There are only two changes that I would make to Ron Dague's treatise. The first would be to expand the answer to question two. You would want to bring your RPM up to about 1500 to assure that the alternator is putting out full amperage. Second, I would spell Torresen differently. Well done, Ron.
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jolie
Revving engine before shutting down
I read in the YANMAR shop manual to rev engine to 1800 rpm or so for a few seconds to burn off any carbon just prior to shutting down.
I read in the YANMAR shop manual to rev engine to 1800 rpm or so for a few seconds to burn off any carbon just prior to shutting down.
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Bob Knott
Mack Boring class too
Yanmar has a two day owner repair class in Braintree at mack Boring. You actually get to work for two days on your exact motor. Well worth it. Don't forget the manual specifically wants you to run for brief periods at near full throttle to clear out the carbon from when you idle too long or run without load. I also kill my engine after throttling up to 2000rpms, and it has always served me well. Enjoy! Bob Knott H380
Yanmar has a two day owner repair class in Braintree at mack Boring. You actually get to work for two days on your exact motor. Well worth it. Don't forget the manual specifically wants you to run for brief periods at near full throttle to clear out the carbon from when you idle too long or run without load. I also kill my engine after throttling up to 2000rpms, and it has always served me well. Enjoy! Bob Knott H380
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R. Palaia
Bad idea to rev engine
Reving the engine is not good, you should let it idle so the temp stabilizes before turning it off. I went to the Mack Boring Diesel class and they said the manual is wrong. You should never shut off an overly hot engine. Roc
Reving the engine is not good, you should let it idle so the temp stabilizes before turning it off. I went to the Mack Boring Diesel class and they said the manual is wrong. You should never shut off an overly hot engine. Roc
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Ron Dague
My take on rengine revving
It doesn't seem to me that increasing engine speed a couple of seconds prior to shut-down will burn any significant amount of carbon. Certainly carbon build-up is a potential problem. That is one of the reasons why you shouldn't idle your engine for lengthy periods of time, (ie: charging batteries). By running your engine until it gets to full, operating temperature, clean fuel, cruising at 1/2 to 3/4 throttle, carbon build-up should be minimal. Think about it: After cruising for 2 hours, idle 5-10 minutes to let engine temperature stabilize. Do you really think revving the engine for 10 or 15 seconds will really clean out any carbon? I don't. If you've been running at proper speeds, there won't be any significant carbon to burn off anyway. And carbon is more likely to "burn-off" under hotter engine temperatures when the engine is under load after running a while, than a quick run-up of engine rpm. So, I stand by my opinion that revving right before shutdown makes no sense. I don't see how it would hurt, just doesn't do any good. But, if it feel good...
It doesn't seem to me that increasing engine speed a couple of seconds prior to shut-down will burn any significant amount of carbon. Certainly carbon build-up is a potential problem. That is one of the reasons why you shouldn't idle your engine for lengthy periods of time, (ie: charging batteries). By running your engine until it gets to full, operating temperature, clean fuel, cruising at 1/2 to 3/4 throttle, carbon build-up should be minimal. Think about it: After cruising for 2 hours, idle 5-10 minutes to let engine temperature stabilize. Do you really think revving the engine for 10 or 15 seconds will really clean out any carbon? I don't. If you've been running at proper speeds, there won't be any significant carbon to burn off anyway. And carbon is more likely to "burn-off" under hotter engine temperatures when the engine is under load after running a while, than a quick run-up of engine rpm. So, I stand by my opinion that revving right before shutdown makes no sense. I don't see how it would hurt, just doesn't do any good. But, if it feel good...
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