I know that we have discussed cruising rpm in Yanmar engines over and over. I have read them, learned from them, but I'd like to relate a recent experience and get your read on this. I have a 3GM30F and I believe the consensus was that somewhere around 2800 was the proper cruising rpm. In any event, there were several statements that higher is better than lower rpm for cruising. Last week, I went out and there was no wind. So we were motoring along for about 4 hours at 2800. In Tampa Bay there is one little area about 10' in diameter and 4' deep. Naturally, I found it. After about 10 minutes, and using full power, I was able to work my way off. Very relieved, we headed back toward the marina and after about 15 minutes, the engine died. It would not re-start. After about another 15 minutes, it started but only ran for less than a minute. Well, thanks to TowBoat/US, we got back to the marina. Since I am next to worthless mechanically, I called my mechanic to take a look. Cooling systems checked out OK, there was just a teeny bit of air in the fuel line, and after bleeding it everything seemed to work OK. Oh, yeah..the coolant system cap gasket was in bad shape, so I replaced the cap. Anyway, my mechanic, whom I have a good opinion of, suggested that I had been running the engine too fast and a combination of the air in the fuel system and overheating caused the shutdown. He suggested that I cruise at 2000 rpm (my boat does about 6.1 knots at 2000.) Maybe my tachometer is off...although it will read around 3200 wide open. I don't know what my question is...but what do you guys think of this incident?*o
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Baloney
Go by what the manufacturer recommends: 80-90% of maximum peak (one hour) rating. I have sat through several seminars from the West Coast distributor. The incidents you recount may be coincidental but unrelated. Rick D.
Go by what the manufacturer recommends: 80-90% of maximum peak (one hour) rating. I have sat through several seminars from the West Coast distributor. The incidents you recount may be coincidental but unrelated. Rick D.
RPM
Allen - Don't know what caused your trouble, but it sounds like the air in the fuel line was a factor in not being able to re-start. Re: RPM - 2800 is not a high engine speed. Check your book for max RPM - I think it is somewhere around 3600. For normal cruising RPM, 80% of max is about right, which would put RPM at 2880. 2000 is too low for extended cruising speed, and will lead to clogging of the mixing elbow. Diesels like to work hard. I went to a seminar at the local Yanmar shop, and they had a mixing elbow cut open on diplay. The thing was clogged completely, victim of low engine speeds. One of my co-workers has a 2GM20F on his boat. He couldn't start it this year, and after some trouble shooting, took off the elbow and guess what? Clogged. He told me he likes to baby the engine, running at only about 2000. He took it in to the shop, and they told him he has to run the engine hard. I have a 3YM30. This is from the manual: "The engine is designed to operate at max throttle (3600-3800)for less than 30 minutes out of every 10 hours. Cruising speed (3400 or lower) for less than 9 out of every 10 hours." The book goes on to say that "when operating at low engine speeds for prolonged time, race the engine in neutral every 2 hours by accelerating from low to high throttle about 5 times." Bottom line - I'm no mechanic. I'm sure others will weigh in on this, but from what I've seen and read, I don't think you caused any harm by running at full power for 10 minutes. And I would stay away from the lower RPMs for cruising speeds.
Allen - Don't know what caused your trouble, but it sounds like the air in the fuel line was a factor in not being able to re-start. Re: RPM - 2800 is not a high engine speed. Check your book for max RPM - I think it is somewhere around 3600. For normal cruising RPM, 80% of max is about right, which would put RPM at 2880. 2000 is too low for extended cruising speed, and will lead to clogging of the mixing elbow. Diesels like to work hard. I went to a seminar at the local Yanmar shop, and they had a mixing elbow cut open on diplay. The thing was clogged completely, victim of low engine speeds. One of my co-workers has a 2GM20F on his boat. He couldn't start it this year, and after some trouble shooting, took off the elbow and guess what? Clogged. He told me he likes to baby the engine, running at only about 2000. He took it in to the shop, and they told him he has to run the engine hard. I have a 3YM30. This is from the manual: "The engine is designed to operate at max throttle (3600-3800)for less than 30 minutes out of every 10 hours. Cruising speed (3400 or lower) for less than 9 out of every 10 hours." The book goes on to say that "when operating at low engine speeds for prolonged time, race the engine in neutral every 2 hours by accelerating from low to high throttle about 5 times." Bottom line - I'm no mechanic. I'm sure others will weigh in on this, but from what I've seen and read, I don't think you caused any harm by running at full power for 10 minutes. And I would stay away from the lower RPMs for cruising speeds.
Wish I saw Rick's post before I started
typing. Then it would have just been "Yeah - what Rick said."
Short and to the point.
typing. Then it would have just been "Yeah - what Rick said."
Short and to the point.Just Cleaned my elbo ( Hi Gregg )
I just had trouble starting my 2GM20 it would not start at all until I cleaned the mixing elbo. Now she runs like new may be even better I can get 7.5 plus at 3200 rpm's against the current,last year I could not get that with out smoke and lower speeds. I strongly recommend runing your deiesl at highe rpm nd checking the mixing elbo every year ,its reall very easy to do on my 2001 2GM20F just four bolts and also check you raw water pump inpeller every year that went on me last year its also very easy to do. You can do this before you get stuck and have to call for a tow and save a lot of cash and ruin a good sailing day. nick
I just had trouble starting my 2GM20 it would not start at all until I cleaned the mixing elbo. Now she runs like new may be even better I can get 7.5 plus at 3200 rpm's against the current,last year I could not get that with out smoke and lower speeds. I strongly recommend runing your deiesl at highe rpm nd checking the mixing elbo every year ,its reall very easy to do on my 2001 2GM20F just four bolts and also check you raw water pump inpeller every year that went on me last year its also very easy to do. You can do this before you get stuck and have to call for a tow and save a lot of cash and ruin a good sailing day. nick
Hmmmm...Thanks, Guys.
Just as I suspected...my mechanic is the only person thats suggested that I run at a low rpm. No, I don't think he's drumming up business...just misinformed. Say, as far as cleaning the elbow, I've always thought that it should be replaced. Nick, are you saying that you cleaned yours...what do you use?
Just as I suspected...my mechanic is the only person thats suggested that I run at a low rpm. No, I don't think he's drumming up business...just misinformed. Say, as far as cleaning the elbow, I've always thought that it should be replaced. Nick, are you saying that you cleaned yours...what do you use?
mixing elbow simple???
This mixing elbow discussion leads me to think about checking mine. However, in every book or manual that refers to maintenance of the elbow, there is almost always a statement about the difficulty of getting the old one off. Is this just an old wive's tale?
This mixing elbow discussion leads me to think about checking mine. However, in every book or manual that refers to maintenance of the elbow, there is almost always a statement about the difficulty of getting the old one off. Is this just an old wive's tale?
Mixing Elbow
Hey Nick - I'm with Rum on this - I thought it was hard to get the thing off. You do it yourself?
Hey Nick - I'm with Rum on this - I thought it was hard to get the thing off. You do it yourself?
Cleaning vs Replacing Mixing Elbow
With regard to engine RPM it's all been said. 80% power or more to keep from causing carbon build-up in the cylinders. If the engine is running at 80% and there is some white "smoke" coming out (depending on outside air conditions) it may mean the mixing elbow needs attention. The mixing elbow on the Yanmar is cast iron and according to our local Yanmar distributor is intended to be replaced (oh.. and they also sell the parts!). However, I remove and clean mine one time and the second time I replace it but.... if one follows this procedure then after it's cleaned it needs to be monitored for cracking. The last time I did this the mixing elbow was at the verge of rusting through. Cleaning vs Replacing may be false economy. With regard to taking the coupling off - it can become really difficult. Talked to a guy today that said he put anti-sieze on his but hasn't had it off since. If the anti-sieze has copper in it don't use it as it will only make things worse. I've used some thread lubricant with graphite designed for very high temperatures that is used on aircraft spark plugs and it seems to work okay.
With regard to engine RPM it's all been said. 80% power or more to keep from causing carbon build-up in the cylinders. If the engine is running at 80% and there is some white "smoke" coming out (depending on outside air conditions) it may mean the mixing elbow needs attention. The mixing elbow on the Yanmar is cast iron and according to our local Yanmar distributor is intended to be replaced (oh.. and they also sell the parts!). However, I remove and clean mine one time and the second time I replace it but.... if one follows this procedure then after it's cleaned it needs to be monitored for cracking. The last time I did this the mixing elbow was at the verge of rusting through. Cleaning vs Replacing may be false economy. With regard to taking the coupling off - it can become really difficult. Talked to a guy today that said he put anti-sieze on his but hasn't had it off since. If the anti-sieze has copper in it don't use it as it will only make things worse. I've used some thread lubricant with graphite designed for very high temperatures that is used on aircraft spark plugs and it seems to work okay.
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