Engine Quit

[diver dave]

from the 6LY3 owners manual: It refers to a certain Yanmar dash panel. (wish pix posting was easier); FRom what I see now in the service manual, pushing the E-stop switch at any station will immediately kill all 12V to the ECU (engine control unit), bringing the engine to a rapid halt. Do you notice that turning off the engine takes several seconds, normally?

text from the manual:

1. To start and stop the engine:• To start the engine, push upper half ofENG ON switch (START).• To stop the engine, push bottom half ofENG ON switch (OFF).Note: The engine will take 2 to 7seconds to stop running afterthe bottom of the rocker switch ispressed.2. EMERGENCY STOP (Figure 9, (2))IMPORTANTUse this switch only in anemergency. Under normalcircumstances, use the ENG ONswitch (Figure 9, (1)) to stop theengine.The engine shuts down suddenly whenthe upper half of the EMERGENCYSTOP switch is pushed. Push the bottomhalf of the switch after the engine hasshut down to return the switch to thecenter.Note: Restarting the engine after usingthe EMERGENCY STOP switchmay be slower or more difficultthan normal starting

 

[Seevee]

from the 6LY3 owners manual: It refers to a certain Yanmar dash panel. (wish pix posting was easier); FRom what I see now in the service manual, pushing the E-stop switch at any station will immediately kill all 12V to the ECU (engine control unit), bringing the engine to a rapid halt. Do you notice that turning off the engine takes several seconds, normally?

text from the manual:

1. To start and stop the engine:• To start the engine, push upper half ofENG ON switch (START).• To stop the engine, push bottom half ofENG ON switch (OFF).Note: The engine will take 2 to 7seconds to stop running afterthe bottom of the rocker switch ispressed.2. EMERGENCY STOP (Figure 9, (2))IMPORTANTUse this switch only in anemergency. Under normalcircumstances, use the ENG ONswitch (Figure 9, (1)) to stop theengine.The engine shuts down suddenly whenthe upper half of the EMERGENCYSTOP switch is pushed. Push the bottomhalf of the switch after the engine hasshut down to return the switch to thecenter.Note: Restarting the engine after using the EMERGENCY STOP switchmay be slower or more difficultthan normal starting

Diver,

My manual is different. There is no emergency stop, no figure 9. (I have a fig 9 but totally different).

And the starting sequence is push the start button, and to stop it's not to rock the same switch back to off.. there's a separate stop switch.

However, my manual is not identical to the boat.

But..... appreciate your thoughts and logic, makes sense, but I'm not there yet.

 

[silver lining1]

The main problem with no load idling is low cylinder pressures. Under no load the diesel asks for very little fuel resulting in minimal cylinder firing and low cylinder pressure. The explosion causes cylinder pressure which push the rings outward and causes them to seat against the cylinder walls. The piston rings seat on the ring lands in the piston and on the walls. Extensive running at no load in theory causes the rings to gently rub on the cylinder wall and not properly seat

This is in addition to loading up valves, pistons etc with not fully burnt fuel. This is quite evident in a mechanical inj system after hours of trolling. My personal opinion is to run at some load say at least 20 or 30 percent with some 50 or 60 percent cruising mixed in for 1 out of 5 hours is best for engine lifetime. I do run to WOT. Few times a year for 3 to 5 minutes to ensure proper WOT is met and that the cooling system is functioning properly

I agree with ncski that your probably getting some air in your fuel intake via racors or fuel pickup that only rarely causes a problem. Have you replaced all seals in your racors and inspected all fittings on the suction side

 

[Wxx3]

Ummm interesting superstitions.

The best advice is to make sure your engine is properly warmed up before putting big load on.

Warm up depends on many factors:
Water flow thru engine, sea water temperature, thermostat, etc.

I idle my SP 135 at 800 rpms, slightly above idle. I like running her about 15 to 20 minutes before I pull away from the dock. That insures I have no issues.

Gets up to operating after 15 minutes.

 

[foggysail]

Railroad engines are not unloaded, they are diesel-electric and there is always a load on them. Fish osts run to the fishing grounds, are fully up to temperature and then are at low load for long periods, NOT idling.

Oh really! If there is no load on the generators......train at rest......there is very little load on the diesel engine.

 

[Seevee]

The main problem with no load idling is low cylinder pressures. Under no load the diesel asks for very little fuel resulting in minimal cylinder firing and low cylinder pressure. The explosion causes cylinder pressure which push the rings outward and causes them to seat against the cylinder walls. The piston rings seat on the ring lands in the piston and on the walls. Extensive running at no load in theory causes the rings to gently rub on the cylinder wall and not properly seat

This is in addition to loading up valves, pistons etc with not fully burnt fuel. This is quite evident in a mechanical inj system after hours of trolling. My personal opinion is to run at some load say at least 20 or 30 percent with some 50 or 60 percent cruising mixed in for 1 out of 5 hours is best for engine lifetime. I do run to WOT. Few times a year for 3 to 5 minutes to ensure proper WOT is met and that the cooling system is functioning properly

I agree with ncski that your probably getting some air in your fuel intake via racors or fuel pickup that only rarely causes a problem. Have you replaced all seals in your racers and inspected all fittings on the suction side

Silver,

Agreed, but the seating of the rings on the piston walls is part of the break in period.... not normal operation. Once seated, it's no longer an issue and you won't get glazing.

But, I still agree on some load after reasonable warm up, but after break in, not quite as critical. And if one operates at fairly low power, the racing procedure is appropriate.

 

[silver lining1]

Seevee. I mostly agree but not completely so a little more detail. First this has nothing to do with why your engine stopped - just to be clear. Cylinder glazing and polishing are different. And definitely the most important time to seat the rings and the cylinder walls is in the first 50 or 100 hours of breakin.

But a diesel can be susceptible to glazing or polishing after breakin due to long periods of idle or very low load. The reason is the cylinder pressure is what causes the rings to seal. And low cylinder pressures combined with low exhaust temps indicate not fully burnt fuel. The low pressure and resulting poor ring seal causes increased blow by of partially burned fuel. This can causing glazing over time and an increase of contaminants in the oil. The cylinder walls are then not properly lubricated and damage results.

So that is why I believe if one runs at 20 or 30 percent load for extended periods it is important to get the engine, oil, cylinder walls fully up to operating conditions for say 1 out of every 3 or 4 hours of run time. And extended idling with no load is even worse for the above reason

Having said that I think it is good to let the engine run for 10 or 15 minutes while untying etc to get some heat in the engine before leaving and I also like to do that at maybe 800 rpms where it idles smoother. Then the engine should be at full operating temp with thermostats open before reaching cruise speed. This is essential because the pistons, piston skirts, rings etc will have reached their design operating dimensions and wear will be minimized resulting from the different thermal expansions and the cylinders can reach proper temps and pressures

 

[mitkofisle]

In response to FoggySails comment about locomotive diesels and generators not being under load at idle --

Large diesel/electric equipment such as cranes and locomotives usually have resistive load banks built into the system so if the machine is not working, i.e. at idle, the load banks come online to put a load on the diesel/generator.

 

[diver dave]

One of the China cities I visited had lots of city buses, diesels. They shut them down at every stop light. At the first intersection, I thought something bad happened. I never quite understood our propensity to keep diesels turning for hours on end with no apparent reason. My dad did the same with a MB diesel car, in the late '60s. I saw a utility truck last year at a substation running with no one there. Not surprised if it ran all night. No, it wasn't powering any city!

 

[foggysail]

In response to FoggySails comment about locomotive diesels and generators not being under load at idle --

Large diesel/electric equipment such as cranes and locomotives usually have resistive load banks built into the system so if the machine is not working, i.e. at idle, the load banks come online to put a load on the diesel/generator.

That may be, I don't know, could not find information on loading an engine just to keep it loaded. But I did find that locomotives DO use resistor load banks but for braking. Somehow...don't know the circuitry... they capture the mechanical energy of motion by transferring it to heat. My guess is that the resistor bank is placed across the electric motor power connections which will attempt to stall the electric motor which most likely is directly connected to wheels. The attached URL describes the procedure. Trains don't use brake bands or pads as cars and trucks do.

http://www.resistorguide.com/braking-resistor/

And something else to consider. I doubt that the railroads would want to just throw away money heating resistors in order to keep a diesel operating with a load. Energy wasted is money wasted.

EDIT: My guess for crane using resistors is to eliminate mechanical braking when lowering heavy objects not to keep an engine loaded. Heavy objects can have huge amounts of stored energy when the object is lifted and when the object is lowered, that energy must be absorbed either with mechanical brakes or electrically with resistors.

 

[Seevee]

Appreciate all the comments about idling, glazing, etc., which are fine, but little to do with my original question.

I'll go on record that with the idling and glazing I'd strongly bet that's not an issue for the vast majority of us.

As for "why did it quit?" I've got a few good replies, and really suspect it's a fuel issue. But looking over the fuel, filters, etc, doesn't look like anythings wrong, but will change the filters in the next day or so.

Also, got a call into Yanmar, to get their perspective.

 

[BandB]

Appreciate all the comments about idling, glazing, etc., which are fine, but little to do with my original question.

I'll go on record that with the idling and glazing I'd strongly bet that's not an issue for the vast majority of us.

As for "why did it quit?" I've got a few good replies, and really suspect it's a fuel issue. But looking over the fuel, filters, etc, doesn't look like anythings wrong, but will change the filters in the next day or so.

Also, got a call into Yanmar, to get their perspective.

Back to your original question. Here's my reaction.

1. Engine has shut off when I return an hour later.
2. So what. I don't concern myself unless I notice something else or it happens when I'm there to observe. There's no pattern, no real sign of a problem. Nothing that says it's shocking engine wasn't running when you returned. I don't know if mine would be because I've never left it at idle for an hour.

I really just think you did something unusual and got an unusual result but if in ordinary operation it's not showing issues, I wouldn't get concerned.

Over the years I've seen diesel trucks stop running when left sitting and not seen alarm on the part of the driver. My uncle had a diesel Mercedes that just didn't idle well. Your idle could be set low but I wouldn't decide that on one incident. Next time I start the engine in advance of using the boat, I'd stay there to observe. Odds are you will never duplicate what happened. This is one of those things where you take a car into the shop but the mechanic can never duplicate the problem you describe. You pick the car up and although they did nothing the problem doesn't recur.

Go boating and stop worrying until you have something more concrete to worry about.

 

[Al]

A lot of interesting replies...

I don't believe idle operation causes glazing. Glazing is almost always caused by improper break in procedures, and not operating at high enough power to break in the cylinders. Idle at break in time is not good and cause glazing.

As for operating at high power to remove carbon deposits, Yanmar has a procedure for that which I subscribe to and keeps the engine running cleaner, evidenced by the cleaner smoke out the exhaust. This is necessary for a lot of low power operation, which is typical of trawler operation.

Now, idling for an hour is not SOP, but should not be a reason the engine quit, nor am I convinced that any harm is done, and the opposing comments here don't make sense. But if you can back them up with real data, I'm listening. Yes, there are probably more carbon deposits with idle operation but a non issue is one does the racing procedure. Glazing? No way.

Ski's answer seems the most logical, and if someone has other possibilities to contribute, would be appreciated.

Until I read this post I was believing that for all of my 50 years of running and operating boats was in error or outright wrong. Not going to delve any further into specific head shaking wonder save to say "Wow"
Always have started and run the power plant at a modest idle (800)RPM at the dock in neutral. In gear if planning to change the oil to raise the temp faster. I want to know if there is a problem lurking about BEFORE leaving the dock. Here in my area this is the standard procedure, not cutting loose and leaving cold. As far as I know in my travels in Southeast Alaska it is the standard procedure.

SeeVee nails the topic to the wall like a moose rack record!!



Al-Ketchikan

 

[Art]

Seevee - I'm sure you've heard of an engine "burping"? On occasion they do what may sound just like a burp. Burp can be caused by various items regarding fuel delivery, item contained in fuel, momentary electrical glitch. These burps usually are fairly meaningless and often become self corrected... such as it seems yours has done. At low rpm a large burp or possiably a group of small burps can stall an engine. Especially if it is not up to full operating temp.


If I were you there are two ways I'd approach this matter.


1. Basically ignore it, keeping it in back of my mind, and continue boating in usual fashion.


2. Set up exact same circumstance of conditions for running engine and read a book or have breakfast aboard for an hour while listening for same stall-factor to occur.