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Old 13-07-2005, 17:50   #1
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My new 3YM30 overheats

I have problems with my brand new 3YM30 on my jeanneau SO35. The engine worked fine for the first 50 hours and had the 50 hr. inspection done by the Yanmar dealer. Since then when I cruise at 2.900-3.000 rpm for an hour the overheating alarm goes on. I put the engine in neutral and put it at 2.000 rpm whilst in neutral. In less than a minute the alarm goes quiet. I had the impeller replaced (one of the blades broken and missing. Same problem. Mechanic looked for missing blade and found it somewhere in the salt water cooling loop. Again after an hour cruising at 2.900 overheat alarm. Yanmar says that because hull is dirty (due to problems in the marina the hull still has no anti-fouling) boat overheats. I have checked the intake under water and it looks clear, but yes hull is full of sea-life.Also please note that max rpm. for my engine is 3.600 I have been told by Yanmar that the boat should cruise at 3.000 rpm without overheating. I am finally having the hull painted with anti'fouling this week, but somehow something tells me that this is not the real problem. The Yanmar dealer has told me that they have another brand new SO35 with the same problem (this one has a clean hull)
Can anyone help with their views? I also need to buy a spare impeller, does anyone know what the Johnson impeller ref. is for the 3YM30?

Thanks in advance
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Old 13-07-2005, 18:22   #2
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Yanmar HELP website

Go to this webiste. There is a Yanmar expert named Dave who authoritively answers questions like yours. In addition, there are customers often giving great info and sharing your problems:

http://www.freeboards.net/?mforum=yanmarhelp

Although it is true that your engine, transmission gear ratio and prop size are selected for a moving hull load, that when overly "dirty" can overload the engine, it is abnormal to break a new impeller blade. Examine carefully the broken impeller for clues as to the type of failure, specifically for some indication that a foreign object caused tearing versus a break indicating a water-starved break.
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Old 13-07-2005, 21:11   #3
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Do Just as Rick has suggested.
But a question, is the water cooling system new, as in, did it come with the engine, or have you kept the old system. If the old one, is it spec'd for the engine requirements. Is it geared right. I doubt that blade broke due to a foriegn object. You should have an intake strainer.
I can direct you in many other area's, but I need to know the answer to the first question first.
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Old 13-07-2005, 23:05   #4
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Bart,
I'd start looking at the prop. From what you've stated already I tend to think Jeaneau my have pitched the boats wrong.

Pat McCartin
Inland Marine Diesel
Buford, Ga
imd_ga@hotmail.com
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Old 14-07-2005, 01:19   #5
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And as a simple sanity check...

Find out if the overheat alarm is functioning correctly. I have seen many instances in my life (in cars) where "idiot light" type systems have malfunctioned and caused the owner much stress only to find out that it was a faulty sensor.
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Old 14-07-2005, 01:41   #6
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There are very few reasons for a new engine (50 hours is new) to overheat. Overload as previously suggested; poor cooling water circulation that can be attributed to clogged intake or output (did the mechanic find all of the broken impeller); malfunctioning heat exchanger or perhaps the engine is not overheating at all. Is there significantly higher output of water vapor from the exhaust during the overheating episodes. It may be a too sensitive alarm or a malfunctioning alarm as previously suggested. Take a look at this website for a possible solution:
http://www.yanmarhelp.com/
Jim
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Old 14-07-2005, 16:54   #7
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Thank you all for your help.

Wheels, the boat is new and came with the engine installed by Jeanneau, nothing has been modified.
Next week I shall be crossing from Denia to Ibiza and into Mallorca (about 25 hours in total) and I have nightmares with hearing the buzz! The boat is now being painted with anti-fouling. I am also changing the 2 blade standard prop for a 3 blade Gori. If problem has to do with choice of prop selected by Jeanneau this should solve the problem.
However, I find it difficult to believe that a new engine can overheat at 3.000 rpm with drag increase or propeller with wrong pitch. Jeanneau has produced already about 500 SO 35s in 2004 and 2005 and I believe they all have 3YM30s.
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Old 14-07-2005, 18:11   #8
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I think I would look at the heat exchanger, for blockage, or the closed side of the cooling system, due to the fact you stated the for the first 50 hours the engine operated normal.
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Old 14-07-2005, 21:29   #9
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Glad you pointed that out John, "Boat operated fine for first 50hrs." That with the "new motor" part made me suspect it was a new install.
OK Bart, first of all, check the entire cooling system, especially heat exhanger. My First question would be, did the Mechanic find ALL missing parts of that broken impellor. A really good mechanic has to be a bit like Sherlock Holmes and he needs to first identify that all the bits are found. If something is missing, it has to be established it is not lodged somewhere.
Next silly question, but often ovelooked, are you running Anti-freeze/anti-boil/anti-corrosive inhibitor. Make sure it is a good one. See waht Yanma recomend. Don't buy anything cheap and nasty. This will insure many things, but the main area of concern is corrosion. Corrosion leads to build up of gunk that will lead to blocking heatexchanger passages and one area often overlooked, the Thermostat. A failed Termostat can lead to and engine over heat or even an engine not heating enough. I have even seen the mistake made, where a faulty stat has been removed and the engine still over heated and thus attention was taken elsewhere. But no thermostat can also lead to engine over heating in some cases.
Make sure all passages are clear. From intake at skin fitting, especially if an intake grill is fitted. If you don't have, fit an inline intake strainer before the pump. A good one to look for, is one that has a clear plastic lid that you can look down through and see that the water path is clear to the skin fitting.
Check the correct impellor has been fitted. Ensure the belts driving it are tight and not slipping. I repeat, look at the path through the heat exchanger. I presume it is an internal exchanger, not a keel cooling.
On some boats, especially older motor powered vessels, Keel cooling, a plate mounted on the side of the hull, or pipes running along the hull, used to be used to cool engine water. These are prone to problems in two ways. When they get a lot of fouling build up, they don't cool well. When they get cleaned, the owner would anti-foul paint them to keep them clean, and the engine would over heat even worse. The paint was a good insulater.

Now to the prop. Don't just throw a prop at this. Big mistake. First you have to ensure it is proped right int he first place. If the engin e can reach full (or close to) RPM, then I suggest your prop is fine. You should not operate your engine at full RPM, but 75-80%. You just need the engine capable of reaching close to full RPM. A three bladed prop may increase the problem. Small low torque high reving engines use less blades. This is because friction is produced by the more wetted surface. Increase number of blades increases wetted surface. I suggest the two bladed prop is the correct one. Especially if this all worked fine in the beggining. Save some money and send the 3 blader back.
Hope this all helps.
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Old 15-07-2005, 08:22   #10
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Thank you Wheels. There is somethingadditional to take note of which I have just been told:
This episode has repeated during the past 15 days on 3 other new Jeanneau SO35, all delivered early this year - like mine- Yanmar Spain is sending new thermostasts and Jeanneau is looking a the design of the salt water intake hose. It may be that water intake is not sufficient due to the design and since the sea temperature has risen to 26-27 celsius the engines may be operating at a higher temperature if the salt water cooling flow is not as big as it should and sea temp is higher. So bearing in mind that there are now 4 boats in the med built by the same yard and with a new engine model (3YM30) - previous SO35s had Volvos until 2005- I believe that it has to do with a design problem. Of course these things happen when you are about to start your cruising holidays with your family in the new boat.
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Old 16-07-2005, 02:51   #11
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Can you use a slower speed....

Have you tried running the engine a lower speed.
I was unable to find a power curve for your engine but the one that I found for a similar engine suggested that the motor could be run as slow as 1100rpm.
This would probably be way too slow for you but 1500 to 1800 may be possible.
The engine would only be producing about a quarter of the heat at this speed and it may be enough to get you through your holliday.
The lower rpm would probably result in a loss of 1-1.5 kts?
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Old 19-07-2005, 18:46   #12
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OK it looks like the problem has been green coolant (apparently it came like this from the Jeanneau factory) which together with high sea water temperatures in the Med (27Celsius) , causes engine to overheat at 2.900 rpm. Green stuff emptied, fresh water cooling system and heat exchanger cleaned and red coolant in. We shall test it again tomorrow. Can the green coolant have its negative effects in the heat exchanger after only 70 engine hours?
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Old 19-07-2005, 20:38   #13
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Not quite sure what you mean by "green" coolant as against what the stuff actually is. Basically the colour is just a dye that a manufacturer adds to there product. There are many Green, Red, Yellow, purple pokadot coolants out there. The important aspect is what the additive is designed to do. Some are just a plain anti-freeze, some are also an anti-boil. Some are better than others.
The main component is usually a form of Glycol. Often Ethylene Glycol, but there can be a couple of different Glycols used. The important properties are the ones often not printed on the bottle. The "Colonel's Secret Recipe" These are corrosion inhibitors and the most important aspect of boat coolant additives. Unless you are like some around here, that choose to live in area's that the water goes solid once a year, the anti-freeze aspect is not really important. Other additives are lubricants for pump bearings and seals, and one that usually sets an additive apart from the rest, is a "wetting agent". It allows faster heat transfer from the engine and to the heat exchanger.
HOWEVER, to go to an over heating engine with just a sea temp change, I would suggest someone has still got it wrong with specing the cooling system and has made it as small as they can get away with. Personally, if your boat is still under a warranty, I would be asking for a larger heat exchanger to be fitted. (if there is room of course)
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Old 20-07-2005, 11:44   #14
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Coolant Colour

The differences between standard and extended life coolants are in the Rust Inhibitors and other Additives. Unfortunately, there is no hard rule determining the colour of standard or extended-life coolants.
The standard coolants utilize silicates and phosphates, whereas the extended-life coolants utilize organic acids (or a hybrid combination).

From “Keeping It Cool” ~ by Paul Weissler“ http://silverstone.fortunecity.com/f...64/coolant.htm
Conventional American coolant (green or gold) contains silicates (a long-used aluminum corrosion inhibitor) and other inhibitors. Silicates work quickly to protect aluminum, but also are depleted relatively quickly in service. They're also somewhat abrasive (being based on silicon-sand), so they've been implicated in water pump seal wear. Advocates say tests show silicates last longer than was commonly believed. And with the latest seal materials, they actually do a better job of protecting the water pump, because they both resist cavitation erosion-corrosion and "repair" any that occurs.

OAT coolant (orange or pink) contains no silicates and no phosphates. It's a blend of two or more organic acids, a specific class of inhibitors with slow-acting, long-life properties. Texaco's Havoline Dex-Cool (also sold under the Goodwrench label by GM) was the first example. Prestone and Peak also have introduced OAT coolants that are chemically compatible with Dex-Cool.

Conventional Japanese coolant (green or red) contains no silicates, but has a heavy dose of phosphates and other inhibitors, including a modest amount of one or two organic acids.

Conventional European coolant (blue or yellow) contains a low dose of silicates and no phosphates, but does include other inhibitors, including one organic acid.

Hybrid European coolant (blue or green) is similar to conventional European, but with a much greater dose of organic acids. It's a balanced formula designed to have the silicates provide the primary protection for the aluminum, then allow the organic acids to provide long-term protection.

Hybrid American coolant (green or orange) contains a moderate dose of silicates, plus a blend of organic acids.

See also: “Coolant Color and its Significance” http://www.englefieldoil.com/PDF/coolantcolor.pdf

HTH,
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Old 01-09-2005, 16:31   #15
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OK Yanmar replaced entire heat exchanger free of charge. The "old" exchanger (engine + boat are new from March) was covered with a greenish layer of silicone (looked like a greassy plastic). Probably the old exchanger could have been cleaned with some solution, but Yanmar was kind enough to put a new one to avoid any further inconveniences. Since then (15 days ago) I have done more trhan 50 hours on my engine which has run smoothly and has not overheated even when cruising at high revs for long periods of time(cruised at 3.300, max revs. for this engine 3.600). So it looks like the type of coolant Jeanneau has been putting on the Yanmar 3YM30 engines is to be blamed. I have heard that other new boats with the same problem have been fixed by either cleaning thoroughly the heat exchanger or replacing it by a new one. Coolant should be orange Texaco havoline, avoid any green stuff just in case
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