Yanmar 2gm engine died

[Hayden Watson]

One thing that no one has mentioned is that a low pressure state can also be from too much oil. If the engine is "making oil" it will be due to either water or fuel getting into the crankcase. If either of these conditions happen, it can often lead to low pressure. The water will cause the oil to foam and sludge which can block the pickup tube. fuel can dilute and thin the oil so that the pump cannot build enough pressure because the thin oil leaves the bearings too fast.

Anytime you get a low pressure (or over temperature) warning, all fluids should be checked before attempting to restart unless you are in a life safety situation where you must get power immediately or risk the safety of the boat.

The thing to remember is that if you destroy the engine in that age of boat, it will probably go to the salvage yard because the repair will likely exceed the value of the boat.

 

[marcham]

Do you check the oil and coolant before each start? If not, that would be a good habit.

Where is the oil level and coolant level at now? (Ideally, we'd like to know if it's changed from before the low pressure event).

You mention first time running in gear.... Is this a new boat to you? Did you not check the engine in gear before leaving the dock? ( Also a good habit, making sure you can shift to forward and reverse before untying).

Assuming this is a new boat to you, had you done a sea trial or mechanical survey prior to purchase? Any clues from those events?

Was there any smoke from the engine?

What was the RPM when you had the pressure alarm?

Maximum rpm or maximum continuous rpm? How long where you at that speed for?

Was this under sail while healing or just motoring?

Is this your first diesel engine?

 

[Davidasailor26]

There is generally no need to baby a diesel engine. If it was running well before you brought the RPM’s up then doing so wasn’t a “stunt” or particularly dangerous. In their own Operating Manual (at least for the YM series; probably similar for the GM) Yanmar says things like “Periodically operate the engine near maximum speed while underway. This will generate higher exhaust temperatures, which will help clean out hard carbon deposits, maintain engine performance and prolong the life of the engine” and “The YM series engines are designed to be operated at maximum throttle (3600 rpm) for less than 5% of total engine time (30 minutes out of every 10 hours) and cruising speed (3400 rpm or less) for less than 90% of total engine time (9 hours out of every 10 hours)”.

Whether or not there was smoke when running at high RPM’s is a very good question. Black smoke would indicate unburnt fuel which could be from overheating. Blueish smoke could be from burning oil. Either of those could’ve been associated with your symptoms. I’d definitely check the oil level now to make sure it’s not too low (as if some were lost) or too high (as if it could’ve gotten frothed up and reduced pressure). Once we know these things we’ll be able to troubleshoot better.

 

[3GGG]

Do you check the oil and coolant before each start? If not, that would be a good habit.
No. But will start

Where is the oil level and coolant level at now? (Ideally, we'd like to know if it's changed from before the low pressure event).
No change in either

You mention first time running in gear.... Is this a new boat to you? Did you not check the engine in gear before leaving the dock? ( Also a good habit, making sure you can shift to forward and reverse before untying).
First time taking it out onto the water for any distance. I had moved it to a new slip a month ago. Maybe 60 ft away
I have been running the engine in neutral at about1/4 to 1/3 throttle for hours at a time while I have been working on the boat. I have run the engine about 20 hrs that way in the last 2 months. I did run it in gear while moored on the advice of the marina diesel mechanic. That was for about 2 1/2 hrs.

Assuming this is a new boat to you, had you done a sea trial or mechanical survey prior to purchase? Any clues from those events?
Boat was given to me by a friend. No survey

Was there any smoke from the engine?
No smoke other than exhaust

What was the RPM when you had the pressure alarm?
No idea, Tachometer isnt working

Maximum rpm or maximum continuous rpm? How long where you at that speed for?
as above. I pushed it for about 2-3 seconds before the alrm went off

Was this under sail while healing or just motoring?
Just motoring

Is this your first diesel engine?
Yes, All other boats have been gas

 

[3GGG]

There is generally no need to baby a diesel engine. If it was running well before you brought the RPM’s up then doing so wasn’t a “stunt” or particularly dangerous. In their own Operating Manual (at least for the YM series; probably similar for the GM) Yanmar says things like “Periodically operate the engine near maximum speed while underway. This will generate higher exhaust temperatures, which will help clean out hard carbon deposits, maintain engine performance and prolong the life of the engine” and “The YM series engines are designed to be operated at maximum throttle (3600 rpm) for less than 5% of total engine time (30 minutes out of every 10 hours) and cruising speed (3400 rpm or less) for less than 90% of total engine time (9 hours out of every 10 hours)”.

Whether or not there was smoke when running at high RPM’s is a very good question. Black smoke would indicate unburnt fuel which could be from overheating. Blueish smoke could be from burning oil. Either of those could’ve been associated with your symptoms. I’d definitely check the oil level now to make sure it’s not too low (as if some were lost) or too high (as if it could’ve gotten frothed up and reduced pressure). Once we know these things we’ll be able to troubleshoot better.

No smoke other than the exhaust. First thing I looked for after I throttled back. Kept watching. Had my feind jump down and look for oil under the engine but there was none. Oil level hasnt changed from when I checked it a week before.

Re: running engine at max speed: Your statement matches what the marina mechanic recommended as well. I know the engine hadnt been run for 2-3 years. I suspect the oil is old and lost viscosity. I was going to do an oil change the week prior but I had the wrong tube for my oil pump. One is on the way now. I figured a short trip wouldnt be an issue as the oil level was good.

 

[dlochner]

Since there is no oil loss either by burning or leaking, a failed oil pressure may well be the culprit. It could be switch itself or it could be the wiring. Check the connections on the switch and to the panel.

And do change the oil and the filter. Wix filters are reputed to be the best.

 

[dlochner]

Don't assume the oil light and the engine dyeing are related. Running any engine at full throttle puts a strain on it. Perhaps your engine is a little tired and under stress has trouble keeping pressure up. In my experience, diesels seem to like to run around 2000 rpm.

What kind of diesel do you have? If you have a diesel that runs at 2500 rpm WOT then the 2000 rpm is perfect. On the other hand if your diesel's WOT rpm is a lot higher, say in the 3Ks then the diesel may not be complaining, but I doubt it likes running slow.

Diesels are engineered for specific duty ratings, which include recommended speeds and durations. Even diesels built on the same block can be designed for different uses. Typical marine diesels for our boats are rated to run at ~80% WOT. Other diesels, like those for gensets are designed and rated for continuous duty a specific RPM, which I believe is about 1800 rpm. When the demand for power goes up, more fuel is injected into the engine and it provides more power to the generator but not more RPMs. This is different from our marine diesels, which increase rpms and power as more fuel is pumped into the cylinders.

Take a look at some of the diesel manufacturers websites and read the specs for different diesels. There is a lot to be learned there for free.

 

[marcham]

Do you check the oil and coolant before each start? If not, that would be a good habit.
No. But will start

Where is the oil level and coolant level at now? (Ideally, we'd like to know if it's changed from before the low pressure event).
No change in either

You mention first time running in gear.... Is this a new boat to you? Did you not check the engine in gear before leaving the dock? ( Also a good habit, making sure you can shift to forward and reverse before untying).
First time taking it out onto the water for any distance. I had moved it to a new slip a month ago. Maybe 60 ft away
I have been running the engine in neutral at about1/4 to 1/3 throttle for hours at a time while I have been working on the boat. I have run the engine about 20 hrs that way in the last 2 months. I did run it in gear while moored on the advice of the marina diesel mechanic. That was for about 2 1/2 hrs.

Assuming this is a new boat to you, had you done a sea trial or mechanical survey prior to purchase? Any clues from those events?
Boat was given to me by a friend. No survey

Was there any smoke from the engine?
No smoke other than exhaust

What was the RPM when you had the pressure alarm?
No idea, Tachometer isnt working

Maximum rpm or maximum continuous rpm? How long where you at that speed for?
as above. I pushed it for about 2-3 seconds before the alrm went off

Was this under sail while healing or just motoring?
Just motoring

Is this your first diesel engine?
Yes, All other boats have been gas

The fact that the engine died leads me to believe a faulty switch is not a play, but you had a critical low oil pressure event.

What coulour was the exhaust smoke?

After it died, did it restart immediately and easily?

The concern here is with a low oil pressure event, the lack of lubrication could damage the cylinder walls and cause very high heat in certain areas. This could have caused the failure (temporary seizure ) you experienced.

At this point, it would be worthwhile to pay an experienced yanmar mechanic to do a compression test.

The low oil pressure could be caused by the old oil temporarily blocking oil passages or foaming. Both would have the same permanent detrimental impact on the engine.

I was in a similar situation with an engine that sat for 3 years. Did 3 oil changes in 100 hrs before the 3rd stopped showing crud (you can never empty all of it unless you have access to the oil pan drain).

I'd also drain the oil and send a sample for analysis to see what the metal content is (would show up if there is piston or cylinder wear).

 

[3GGG]

What coulour was the exhaust smoke?
Normal. Slightly gray. I kinda looked like there was more? Like on starting and there is too much fuel?

After it died, did it restart immediately and easily?
Yes.

The concern here is with a low oil pressure event, the lack of lubrication could damage the cylinder walls and cause very high heat in certain areas. This could have caused the failure (temporary seizure ) you experienced.

At this point, it would be worthwhile to pay an experienced yanmar mechanic to do a compression test.
OK. I will see who I can find

The low oil pressure could be caused by the old oil temporarily blocking oil passages or foaming. Both would have the same permanent detrimental impact on the engine.

I was in a similar situation with an engine that sat for 3 years. Did 3 oil changes in 100 hrs before the 3rd stopped showing crud (you can never empty all of it unless you have access to the oil pan drain).
I was thinking of doing this as well to try to clear out some of the old oil.

I'd also drain the oil and send a sample for analysis to see what the metal content is (would show up if there is piston or cylinder wear).

 

[Rich 35.5]

That sounds like the oil level may be too high. If it is, it gets aerated by the crankshaft, air compresses much easier than oil, so low oil pressure.

 

[Ralph Johnstone]

I was in a similar situation with an engine that sat for 3 years. Did 3 oil changes in 100 hrs before the 3rd stopped showing crud (you can never empty all of it unless you have access to the oil pan drain).

That sounds like an excellent idea because it's FREE. Almost. Do this before shelling out money for a mechanic or anything else.

DO NOT run the engine again with that old oil. Change you oil and idle at the dock for a half hour. Change the oil again to see what the old oil looks like. If it's not bad, take it out and run it for a couple of hours. Return to the dock and change it again and see what the previously replaced oil looks like. There will be some carbon in the new oil as it only takes a few hours to turn as black as ink. Even blacker if that's at all possible. Keep changing oil until the oil is reasonably clean for diesel oil.

I have been running the engine in neutral at about1/4 to 1/3 throttle for hours at a time while I have been working on the boat. I have run the engine about 20 hrs that way in the last 2 months.

I can think of nothing worse for a diesel engine.

As another check, run your engine at idle (not like above) and shake the wires leading to the pressure sensor on the engine. See if you can get an alarm anywhere on the wiring. Try disconnecting the wire to the pressure alarm to ensure there is a LP alarm when there should be and the alarm is in good condition.

From what you say about no change in oil level, I wouldn't be too concerned about engine damage YET. Unless the engine shows real problems, I would continue with the checks as suggested by others.

Keep in touch.

 

[3GGG]

That sounds like the oil level may be too high. If it is, it gets aerated by the crankshaft, air compresses much easier than oil, so low oil pressure.

There are two marks on the dip stick. a low and a high. my oil reads at about 3/4 between

 

[3GGG]

That sounds like an excellent idea because it's FREE. Almost. Do this before shelling out money for a mechanic or anything else.

DO NOT run the engine again with that old oil. Change you oil and idle at the dock for a half hour. Change the oil again to see what the old oil looks like. If it's not bad, take it out and run it for a couple of hours. Return to the dock and change it again and see what the previously replaced oil looks like. There will be some carbon in the new oil as it only takes a few hours to turn as black as ink. Even blacker if that's at all possible. Keep changing oil until the oil is reasonably clean for diesel oil.
I will do this. My first diesel so I don't know what clean diesel oil looks like. Should I assume after 3rd full oil change it would be reasonably clean?



I can think of nothing worse for a diesel engine.
Why is this?

As another check, run your engine at idle (not like above) and shake the wires leading to the pressure sensor on the engine. See if you can get an alarm anywhere on the wiring. Try disconnecting the wire to the pressure alarm to ensure there is a LP alarm when there should be and the alarm is in good condition.
OK. Will do

From what you say about no change in oil level, I wouldn't be too concerned about engine damage YET. Unless the engine shows real problems, I would continue with the checks as suggested by others.

Keep in touch.

 

[jssailem]

I don't know what clean diesel oil looks like.
It looks nearly the same and the oil that is in your quart container as you empty it into your diesel engine.

The Carbon Black (CB) which turns the oil black is partially burnt fuel. It accumulates in the engine when the engine is run at low RPM's as the engine does not get hot enough to burn all the fuel being sprayed into the cylinders. Under load (turning the prop) and at 80% plus of wide open throttle (WOT), sometimes will blow the CB out in the exhaust. Flushing the oil should also help clean it out of the oil passages and sump. If you run under load at the dock be sure to secure the boat to the dock and that the dock cleats can handle the stress.

 

[3GGG]

I don't know what clean diesel oil looks like.
It looks nearly the same and the oil that is in your quart container as you empty it into your diesel engine.
OK.

The Carbon Black (CB) which turns the oil black is partially burnt fuel. It accumulates in the engine when the engine is run at low RPM's as the engine does not get hot enough to burn all the fuel being sprayed into the cylinders. Under load (turning the prop) and at 80% plus of wide open throttle (WOT), sometimes will blow the CB out in the exhaust. Flushing the oil should also help clean it out of the oil passages and sump. If you run under load at the dock be sure to secure the boat to the dock and that the dock cleats can handle the stress.
During the runs after the oil changes, i need to run 80% of WOT? I noticed when I tried to push the throttle it would revert back to a lower setting. Is that correct? Not sure what WOT would be in that case

 

[dlochner]

During the runs after the oil changes, i need to run 80% of WOT? I noticed when I tried to push the throttle it would revert back to a lower setting. Is that correct? Not sure what WOT would be in that case

If the throttle won't stay at WOT, it is a problem with the throttle mechanism.

The black in the oil is carbon from blow by in the cylinders. At idle, the engine does not get hot enough for the rings to expand and seal the piston, thus some oil gets by and some partially burned fuel also gets by. Long runs at idle will also cause the cylinders to glaze, which is apparently a bad thing, I don't fully understand. The other issue is carbon deposits in the exhaust elbow. The partially burned fuel collects on the elbow restricting exhaust flow and helping to accelerate corrosion of the elbow.

Running the engine under load and at high rpms causes the rings to heat up and seal, the fuel to be more completely burned, and any carbon deposits in the exhaust elbow to burn off. All good things for a diesel.

 

[jssailem]

I noticed when I tried to push the throttle it would revert back to a lower setting. Is that correct?

Your engine shows an RPM on your Tach.
The spec for the Yanmar 2GM is
The continuous rating output at the crankshaft is 11.8 kW, at 3400 revolutions per minute (rpm). The maximum output at the crankshaft is 13.4 kW, at 3600 rpm.
80%is 2880 RPM. The Spec says you can run the engine at 3400. On your boat you need to identify what RPM gets you to your hull speed. If it is below 3400 that would be golden. If it is at 2880 that would mean you could run the engine at that RPM all day and go as fast as your boat hull permits. You would have reserve power to deal with foul weather conditions.

For this exercise to resolve the oil issue, I would run the engine spinning the prop at the dock fast enough for the engine temp to get up to 125ºF. I would record the RPM needed to reach this temp range. Once the engine temp hits that range I would shut down and change the oil. Note the oil will be hot take precaution not to get burnt. Pumping out the oil should be easy. Change the filter and then pour in new oil. Repeat the process.

The throttle drift is a separate issue. More info is needed. I would look at the linkage. You may have something loose in the linkage. Throttles are designed to be set and stay at that position. Not sure what type of throttle linkage you have.

 

[jviss]

When the demand for power goes up, more fuel is injected into the engine and it provides more power to the generator but not more RPMs. This is different from our marine diesels, which increase rpms and power as more fuel is pumped into the cylinders.

Dave, I do not believe that is correct. Marine diesels, as with most/all diesels, have speed controls: a governor connected to the high pressure injector pump. When we advance the so-called throttle [1] it adjusts the governor for a higher target RPM, and the governor controls the injector pump to supply the correct amount of fuel to maintain that RPM, over varying loads.

[1] there is no throttle on a diesel engine. There's a speed control, and is connected to the governor, and controls the engine RPM. It works in concert with the injector pump to supply the right amount of fuel to maintain the RPM over varying loads. It's weird, as even diesel vendors/manufacturers will use the term throttle and "WOT" (wide open throttle) in their literature, even though there's no throttle.

 

[dlochner]

[1] there is no throttle on a diesel engine. There's a speed control, and is connected to the governor, and controls the engine RPM. It works in concert with the injector pump to supply the right amount of fuel to maintain the RPM over varying loads. It's weird, as even diesel vendors/manufacturers will use the term throttle and "WOT" (wide open throttle) in their literature, even though there's no throttle.

The American Heritage Dictionary might disagree.

throt·tle (thrŏtl) Share:​ n. 1. A valve that regulates the flow of a fluid, such as the valve in an internal-combustion engine that controls the amount of air-fuel mixture entering the cylinders. 2. A lever or pedal controlling such a valve. tr.v. throt·tled, throt·tling, throt·tles 1. a. To regulate the flow of (fuel) in an engine. b. To regulate the speed of (an engine) with a throttle. 2. To suppress: tried to throttle the press. 3. To strangle (a person); choke.

Dave, I do not believe that is correct. Marine diesels, as with most/all diesels, have speed controls: a governor connected to the high pressure injector pump. When we advance the so-called throttle [1] it adjusts the governor for a higher target RPM, and the governor controls the injector pump to supply the correct amount of fuel to maintain that RPM, over varying loads.

Generators that produce AC directly, and not DC converted to AC, must maintain a constant rotational speed in order to produce the desired frequency, i.e., 60hz.

 

[jviss]

M

Generators that produce AC directly, and not DC converted to AC, must maintain a constant rotational speed in order to produce the desired frequency, i.e., 60hz.

Most modern generators are inverter-based, so, not necessarily.