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Discussion Starter · #1 ·
Hi guys I would like ask here for some advice regarding problems with starting my Yanmar 3GM30 engine. I am quite new to sailboat engines (previously sailed only charter boats, so except refueling, oil level checking and belt exchange I have no experience) so, please be patient to my problem description.

Let me describe sequential events. During summer I have sailed from Copenhagen to the Lofoten (north of Norway) and back. During the trip, we were motoring a lot since some passages were with no wind at all or right to the nose. During motoring, we experienced low oil pressure alert time to time. When occurred, I've refilled oil by 15w40. But consumption of oil was enormous (about 1 gallon per 80 - 100 hrs of running). There was little bit amount of oil under engine but no more than a quarter of a pint. Once we stuck with oil alert on one island and was forced to use one quart of 10w40. But engine was all the time running smoothly with no problems. On the end of summer, after two and half month of sailing, when returning after the whole trip to home port in Copenhagen suddenly engine revs fluctuated and in one minute the engine died. I tried to start again with no luck. I refilled oil and diesel just for case (not needed, but just to be sure), let the engine cool and after 40 minutes it started again and we managed it to home port. Since then we were several times motoring through the marina just to change berths with no problems. Week ago, we sailed to neighbouring marina for diesel. Everything went well, but after 2 hrs revs fluctuated again and in about 30s engine died. Since than, I was unable to start it again.

I have noticed, that from the exhaust is getting out white to gray smoke and in cooling water (salt water cooled) are oil droppings (to be more accurate, water behind boat has marks of oil in it)

Anybody with same experience or with an idea what can be wrong? Thx a lot.
 

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One of None
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It is a diesel engine that happens to be in a sailboat. Welcome to sailnet!

You probably should not have continued to use the engine while it was using oil like it was,. And they don't fix themselves by ignoring the problem. But as they say, that is "water under the bridge" (or in this case, oil out the exhaust )

First guess, head gasket,
 
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that much oil usage would indicate that the ring are bypassing and you are burning the oil. is it oil in the cooling water or black carbon from the exhaust. if oil in the water it's coming from the rings. could be head gasket but that does not explain high the oil usage. there a lot of things on and older GM engine that could cause out not to run. looks like it may be ready for overhaul but first check the exhaust elbow for a leak in side the elbow as this can cause white smoke. slow cooling water flow can also cause white smoke and a hot engine so you will use more oil. then check the injectors if they will come out . if they don't come out then you will have to pull the head which will let you check the head gasket. First thing I always check is the exhaust elbow, many times it is the cause of the problem and they need to be cleaned often anyway so it is the best place to start.
 

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Bet head gasket has corroded.firstly allowing oil to get into cooling. More corrosion and water into cylinders and now no compression. While you got the head off do the injectors,check for ridge wear and piston flop to determine if you need to go deeper .
 

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Sounds like you may have a number of things going on.

The apparent small leak under the engine is concerning. There should be no oil there unless you spilled it while filling. A leak of that scale suggests a failing gasket.

Was the engine speed fluctuation a loss of power or surge in power? Loss in power could suggest fuel starvation (clogged filters, line, injectors), while surging to higher RPM when hot would suggest burning engine oil (which other symtoms seem to suggest).

In any case, I wouldn't rely on that engine outside the marina until you get it sorted out.

If you haven't already got it, you can download the service manual at: http://www.jeanneau-owners.com/Manuals/3GM Engine Service Manual.pdf
 

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If you keep running the engine with a blown head gasket you're going to wind up with bigger problems for sure. Could be rings or a cracked head but sounds like head gasket.
 

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Farr 11.6 (Farr 38)
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For better or worse, old 3gm30's can be real leakers. They have small tubes that feed oil to the valve galleries that are notorious for developing leaks in places you can't see, and gaskets and seals that can "ooze" a bit when the engine warms up. Frankly a small amount of oil in the sump below the engine is not something to worry about on its own. That is what oil dippers are for. But 1 gallon per 80 - 100 hrs, that is serious. My old 3GM30 uses roughly 1/2 a quart in 100 hours and it still does have minor gasket leaks. (Two years ago, I replaced the the front and real seals, valve train cover gasket, and also the oil gallery tube, and I still get oil drips below the engine.)

But as others have said, that much oil sounds like rings, valve guides or a head gasket to me. The pressure alarm suggests rings, and/or valve guides. If it was a head gasket, you would expect to see water in the lube oil (milky lube oil or worse) so that would not be my first guess. But unless there is a catastrophic failure of the rings, once you were able to get the engine to start when cold, I would expect the engine to continue to run with bad rings. Valve guides even more so.

So if I had to guess you actually have more than one thing happening. In other words, I suspect that the oil is being lost through multiple locations, but that may not be related where I suspect that the smoke is coming from, and may not be related to the reason that the engine quits running after a bit may even be a third thing.

My guess is the smoke could be a clogged exhaust elbow, maybe combined with questionable injectors, combined with maybe questionable fuel.

My guess the quitting engine could be some mix of water in the fuel, a bad fuel lift pump, air leaking into the fuel lines or an improperly bled fuel line with the air in the line heating up, expanding and blocking fuel flow, with the other stuff merely adding to the problem.

But those are only stabs in the dark,

Jeff
 

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Doubt this is your problem but something every gm series yanmar should change. There is an external oil line that runs from stbd side of engine around in back to the portside. This line is steel and runs under the exhaust outlet at the rear of the heat exchanger. If there is any salt water leakage at this fitting, the line is surely on its last legs and disaster is just waiting to pounce. Even if the exhaust flange isn't leaking the pipe can rust through. Changing it is a PITA as it snakes around the engine mostly out of site. Changed mine with the engine out which made it easier but can be done with engine in place if you have decent access. Did have to pull the starter to get at port side fitting. The new line is copper or some coppery looking material so won't corrode away to disaster.
 

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Discussion Starter · #9 ·
Guys, thank you very much for so many answers. I know, it is hard to guess what is wrong, when you cannot see the engine on your own, but you try it and for that, I am so thankful. I have invited a mechanic, but it was probably wasting money. He did not ask on a sequence of events and said he will do his own judgment. His first guess was that I have air in fuel leading pipes. He changed some screws and plastic hose coming from fuel tank to engine's fuel intake made bleeding but the engine did not start. His second guess was, that my starting battery is dead. Brought his own, but again, no start. Then I told him that is time to hear the story. After that, he said, that air in fuel overheated the engine, therefore the oil leakage and then that there is damage to at least 2 valves and the lack of compression suggests that stamp shrinkage may be defective and damage to the top piece. But he did not open the engine and did not hear him, so I have no clue, how he could be so sure, that this is the problem. His suggestion was to buy a new engine because the repair would cost almost the same money. Since, according to the previous owner, the engine had the mechanical revision in 2007 and I paid a lot of money for the boat, I definitely cannot afford a new engine, so hoping for best and trying to get as much information as possible.

As overbored wrote, I will do the check of exhaust elbow. I have read this in several discussions and probably can manage by myself.

To Phil Carlson - I did not feel any power fluctuation. Just seen revs fluctuation on a clock. But it was a matter of secs and wavy, so hard to say. And thanks for manual. Already printed :)

Now I am looking for a different mechanic in the area of Copenhagen to cross-check conclusion of the previous one. Next week I will check the exhaust elbow. We will see.
 

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Farr 11.6 (Farr 38)
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That is a wild story. If the mechanic did not "open the engine", what made the Mechanic think that it was a valve problem with two or more valves? What made him think that there was a compression problem? Did the mechanic do a check compression? In any case almost none of that makes a lot of sense.

Air in the fuel injection system is a possibility, as the mechanic said, or an air leak in the fuel line is another, but that wouldn't normally be a run time related delay. Air in the fuel injection system would be easy to diagnose and repair. Did the mechanic bleed the system?

At the heart of it you really need to have a reliable diagnostic performed to figure out what is happening. There are several parts of your story that provide clues in that diagnosis process:
1) losing oil,
2) runs when cool but dies after a while (which may not be a temperature thing but a water in the fuel tank thing)
3) oil pressure alarm
4) Engine fluctuating and dying (that sounds like a fuel problem, have you checked the fuel tank bottom for sludge and water, water separator, fuel filters, bleed screws and fuel filter gasket.)


But even if the mechanic is right that this is internal, Yanmars tend to have very robust lower ends, which means that you probably don't need a total rebuild. There are various level rebuild kits for the 3GM since these were very popular engines. Assuming the injection system and all of the externals are in good shape, at least in the US a skilled mechanic can rebuild one for well less than the cost of a new engine depending on whether this is just a valve job, or the pistons and cylinders need to be pulled, and the cylinders honed or bored. In the worst case, you can buy short blocks for these engines pretty affordably. Yanmar parts are pretty affordable as these things go.

You can save a lot of the cost if you are able to remove and reinstall the engine yourself as well as remove the extraneous externals (minimally the transmission and alternator) and deliver it to a mechanic. (The mechanic should be able you to tell what to leave on the engine and what to remove.)

Its not a terrible job to pull these engines is there is room to work and get the engine out. A few years back I had to pull my engine out of my boat when I was in my mid-60s on a day that was 25 F degrees hotter than my age. I unbolted maybe 25-30 items, rigged up timbers and blocks and tackles and out it came. Take lots of pictures ahead of time, write down and number the steps that you followed and place the parts in Baggies that are well labeled. Notice if all the bolts coming out are the same length since some parts have longer and shorter bolts that are the same diameter and label which hole they came out of if they are.

Good luck,

Jeff
 

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That is a wild story. If the mechanic did not "open the engine", what made the Mechanic think that it was a valve problem with two or more valves? What made him think that there was a compression problem? Did the mechanic do a check compression? In any case almost none of that makes a lot of sense.
Personally a compression test would probably give a false high ratio due to the amount of possible oil present in the cylinder(s). No one has mentioned the amount of hours nor past maintence history. I'd probably look at a minimum of a top end tear down for a look see..
 

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Farr 11.6 (Farr 38)
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Personally a compression test would probably give a false high ratio due to the amount of possible oil present in the cylinder(s). No one has mentioned the amount of hours nor past maintenance history. I'd probably look at a minimum of a top end tear down for a look see..
I basically agree with you on all points. The reason that I asked about a compression test was the mechanic's comment that there were two or more bad valves. My thinking was similar to yours that if the rings were the problem and there was lube oil in the cylinders there could be a higher than reality compression reading. But if the valves and valve guides were the problem then the cylinder would still show low compression.

But the thing that seems really strange about the Mechanic's comments is that a diesel with really bad compression and bad valve would not even start, But on a diesel with even half way decent compression and valves once it started, it would not want to cut out the way that was described. To me the more I think of it, the engine cutting out sounds solely like a fuel system problem, which should be easy to diagnose and repair on a simple engine like the 3GM 30. There clearly are other things going on with this engine (oil loss being a major issue) but none that can think of would explain the engine cutting out.

Jeff
 
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Your experience with that mechanic does not inspire confidence. Starting battery, really? It's a diesel, if it turns the engine, it's not the problem.

I'd say a second opinion is in order. As Jeff mentioned, these are not overly difficult engines.
 

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I have little faith in your mechanic based on your description of his visit. And saying that the repair would cost more than a new engine when he didn't even take the head off is the icing on the cake.

I feel there may be at least two issues going on. One related to the starting problem and the other related to the oil use. The first is probably fuel system related. For the second, I think that as a minimum, the head has to come off. Find a mechanic that knows what he is doing and will do this.
 

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Rig up a temporary fuel supply that you know to be clean fuel.
Tie the boat up well (plenty of lines) and run the motor under load to see if it cuts out.
If it doesn't, then the engine stopping is a fuel problem.
I don't think it is a piston siezure. Piston siezures tend to drop the revs abruptly.
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Your oil consumption is high, but you still have enough compression to start.
It sounds like you will need a re-bore to cure that one.
.
I ran a Volvo MD17C with high oil consumption (indeed worse than yours - close to a litre every 16 hours), and it ran for years like that. A re-bore cured it.
 

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Good advice here. Jim is spot on with possibly two or more issues at the same time. The God of internal combustion has a fickle sense of humor. Everything runs great for years and then she throws two or three problems your way at the same time. Since everything has been so smooth one assumes it must just be one issue when in fact...

Someday the maritime god of electric propulsion will strike down the god of internal combustion and we can all be free. :)

(5.5 years 60K miles of driving an EV and here is my complete list of maintenance: 1. Rotated the tires 2. plug it in at night or at work. 3. There is no 3)
 

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Discussion Starter · #17 ·
Hi guys, it is winter and so sailors here in Copenhagen do not sail and rest. And some, like me, are working on their homework. In September, I posted here the question about not engine malfunction (not starting). Lot of you provided opinion on what can be the cause. Due lack of time I started with repairs week ago. Here is a description of my effort. Hope it will help somebody in future and.

Firstly, I have involved another technician since the first one did not convince me with his conclusion based on poor analysis and technician performance. The second was much more professional. He also noted (to my previous description) small amount of white smoke coming from air intake silencer. He concludes 5 possible problems/causes (which correspond to some of yours):

1) Jammed/broken exhaust elbow
2) Valves broken or not sealing well
3) Cylinder rings broken or not sealing well
4) Broken cylinder
5) Broken cylinder block

Problems number 2) - 5) needed an opening of the engine. His advice was to unmount engine and deliver it to his workshop for testing and possible dismantling. I do not have to add, how pricy this all would be. So I decided that in my age I should finally learn something about engines and did all work by myself. Now my findings:

1) Exhaust elbow was little corroded but basically ok.
2) I removed the cylinder head. Head gasket was ok (not corroded or blown). But what first hit me into eyes was somehow oily air intake valves on two cylinders. (One cylinder was completely dry, just some build up. The other two were dry too, but except these intake valves). So I poured ethanol to intake and exhaust holes and tested if the valves are sealing. Guess what, they are not. Could be this problem of oil disappearing, smoke in the air intake and changed the colour of exhaust?
3-5) Cleaned top of cylinders and chambers and look ok to me. Some build ups on top of each + one small crack on one of them. But no cracks on chamber walls. Did a test of rings sealing (pour diesel into each cylinder chamber and looked for level change the next day and found none).

Now I will have to get somewhere valve grinding paste (I am strange to Denmark, so get something here is for my quite difficult, as they have their Danish names and, as look to me, Danish people do not repair much by themselves, so a lot of stuff is hard to get) and clean valves make them sealing once again. And buy new gaskets to be able to mount the engine together and try to start again.

But one thing I have to find out. Original head gasket did not have some holes drilled but on cylinder head and block were in the same place holes for cooling water. My common sense is telling me, that these holes in gasket should be open for better water flow (and new gasket I have found on the internet are with open holes) but not sure. It can be some special Yanmar design I do not get.

But anyway, as soon I will know something new, I will post it again. Not sure if photos will attach so here is a link to google album https://photos.app.goo.gl/3Rwqvywrs2nwZH5ZA
 

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Thanks for the follow up, great to see how you are progressing.

I don't know what's going on with that head gasket. I've looked at several images of 3GM head gaskets and they don't seem to have holes there either. Not clear if it's a punch-out piece or what. The diagram on page 4 of the pdf linked below pretty clearly shows coolant flowing through those ports.

www.j30.us/files/yanmar-cooling-system-chapter8.pdf

I'd note that your ring test won't find a leak or blow-by that would occur when the engine is operating. It's a good sign, but you'll want a proper compression test before you are done.
 

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Discussion Starter · #19 ·
You are right. I did not notice they have the water flow on that picture. (And seen it several times :)) You opened my eyes :) It is really strange. I will ask dealer and technician on their thoughts and do some internet searching. Then I'll post conclusion on this here.
 

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Excessive oil usage is certainly a problem with any engine and must be addressed.

However, all engines will use oil between changes. Some maybe a negligible amount. It is not necessary to keep an engine "full".

Most of the time I spent as a captain of a 60 ft. tour boat with twin Volvo diesels I topped off the oil each morning as needed until I was told by our mechanic that fill up was not necessary because each engine would use some oil then stop at the level it liked to run. When I began observing per his instructions I noticed one engine consuming slightly more oil than the other, then consumption would stop.

I wish I had learned that as an auto shop student in high school.
-CH
 
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