Engine Quit

Here you go - read Steve on this topic. Maybe his opinion carries more weight?

The Perils of Chronic Under-Loading | Steve D'Antonio Marine Consulting

There's lots of opinions on this, maybe because diffetent types and ages of engines live different lives.

We have discussed it here many times with no definitive answers eiter way.

But without cutting and pasting a bunch of stuff to lead newbies in tbe wrong direction, all I can say is learn as much as you can about your particular engine(s) from various sources.

We have seen even some experts here are suspect in their overall knowledge.

For all of you who want to bury yourself deep in the study of the subject with data and expert opinions, have at it with this:

https://daim.idi.ntnu.no/masteroppgaver/011/11083/masteroppgave.pdf

BandB said:

For all of you who want to bury yourself deep in the study of the subject with data and expert opinions, have at it with this:

https://daim.idi.ntnu.no/masteroppgaver/011/11083/masteroppgave.pdf

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Good link BB. But the article and thesis focuses on low load, not NO load.

As example, there are studies and guidelines for no load engine operation when heavy equipment is purposely left running at idle during extreme cold weather. External oil and coolant heating can be utilized as well at these -40 conditions.

In Seevee's case doubtful you'd find any worthwhile data to support or counter his practices since no one recommends a prolonged cold start idle and walk away at the dock. Of course everyone has the opportunity do as they wish, no matter the rationale.

psneeld said:

There's lots of opinions on this, maybe because diffetent types and ages of engines live different lives.

We have discussex it here many times with no definitive answers eiter way.

But without cutting and pasting a bunch of stuff to lead newbies in tbe wrong direction, all I can say is learn as much as you can about your particular engine(s) from various sources.

We have seen even some experts here are suspect in their overall knowledge.

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This is my believe too. I don't trust the experts and the generalizations. Know your own engine. Educate yourself. Then proceed. I read everywhere information on generators which is completely contrary to what the manufacturer has said on some of our gens.

I wouldn't personally run an engine and hour at idle but if Seavee feels ok doing it then fine. I have far more problem with leaving the engine running on an unattended boat for that length than any danger to the engine. I don't know how his temperatures look doing what he does or how clean his exhausts are or anything else pertinent. I wouldn't do it out of being extra cautious and not knowing if it might hurt or not, but that's just me and not something I can say he's right or wrong on. I also wouldn't be surprised or upset that run at idle and engine shut off.

I don't think it is the best thing for the engine to idle, especially from a cold start, but I would not worry a bit about it.

I have logged LOTS of hours on my Cummins 6CTA 450 trolling at 600rpm, just a touch over base idle of 550. I know it is not the best thing for it, but I want fish and that's what it takes. So be it. If I need to put cylinder kits in, I will. And continue afterward to run it exactly the same.

One thing I do is right after cold start I kick up rpm to about 800 til I get the lines off. Do the same if I need to idle it in neutral. Quiets and smooths it out, and might keep oil moving a bit more.

Lots of engines have idled and idled and idled without any apparent harm.

Worry not.

I think this issue is overblown at both ends.

IMO idling for 5 minutes or so won't do any damage to any diesel engine. And I do believe slowly warming up an engine is important. I usually take 15 minutes or more to reach normal cruise rpm. And if I accidentally take 15 minutes to get underway it I'm not going to be the least bit upset about it.

Coolant wise my little Mitsubishi S4L2 (37hp) idles after less than 10 minutes running from cold at 180f. It tops out at 190f at cruise. But just the coolant has warmed up .... not pistons, oil, camshaft or most other moving parts.

The reason for slow warmup is to allow engines parts to expand slowly and as close to evenly as possible. Exhaust valves for example warm very fast compared to camshafts.

I think the old saying "blow her out" is an old expression that has nothing to do w modern engines gas or diesel. Mechanical diesels propably do "load up" w excessive unburnt fuel under certian conditions that would only require 1/3 to 1/2 load to clear them of unburnt fuel .. not "let-er-rip" type running. None of the running mentioned above has ever caused any black smoke or anything similar.

Just my opinions.

Regarding the engine quitting ...

I had that problem for years. Mostly just slowed down a little or a lot. It finally quit in Georgia Strait. Got towed by a passing boat - lucky me.

Later I concluded that bits of sealant was the cause (causes) of the slow downs/quitting. I took apart the entire fuel manifold replacing thr hoses, fittings and throughly cleaned all the pipe fittings using sealant sparingly and only on the upper threads. Hasn't missed a beat since.

I offer this as an engine quitting story but don't belive it's the OP's problem.

Xsbank said:

Here you go - read Steve on this topic. Maybe his opinion carries more weight?

The Perils of Chronic Under-Loading | Steve D'Antonio Marine Consulting

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Xsbank,

Good read, and I totally agree with it, as I do the report posted by BandB.

In the case of my idling for an hour, I must emphasize that it's not the norm, in fact this was the only time any one of my boats has idled for a hour... ever. It was one of those things... thought she was ready to board... just a few more minutes... a few more, and next thing it was an hour. I'll probably never do that again.

But, if the idling caused the engine to quit, I'd like to know. Will look deeper into things, just to try to confirm something.

Also, an hour of idling is not the best operation (same in cars and planes), but doubt that it hurt anything, unless it was the bulk of the operation.

BandBs article addresses "low load" as operations below 40% of max rated power, which isn't far from where a lot of us cruise. And the problems with continuous operation at low power are real, but not hard to avoid. One needs to have the temps up to burn off the contaminants, especially water. Surprising, it's about the same with aircraft engines (and that's my field as an A&P and AI), similar, but different.

As for glazing, I'd bet that the vast majority of the time, glazing is a result of poor break in, as noted by BandBs article.

How the heck did we get so far off topic :face palm:

But, appreciate all the comments.....

Seevee said:

But, if the idling caused the engine to quit, I'd like to know. Will look deeper into things, just to try to confirm something.

Also, an hour of idling is not the best operation (same in cars and planes), but doubt that it hurt anything, unless it was the bulk of the operation.

.

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I doubt it hurt anything myself, but I'm not at all surprised the engine quit at some point in the process. Engines stop while idling a lot for different people, sometimes bad cases when they're docking. I have had cars in the past where the idling was set too low and they'd stop at lights occasionally, but as soon as the idle was set right, the issue was gone.

I think it could be one of a million things and unless it happens again with you on the boat you'll never have an idea. Even then you might not. Only if whatever caused it gets worse and more identifiable. Still my guess is it's nothing and as you say, you'd never left it for an hour of idling before so not like you can say this was unusual for it to quit. I wouldn't worry about it.

You could leave it idling and sit in the boat and wait to see how long it will run before it quits, but personally I think that would be sort of dumb to do.

I'll bet there is a little bit of an air intrusion issue. Once power is up, the air washes through without issue. Only shows up in weird ops like the hour idling. Tracking down the issue might be a bugger. If engine runs fine otherwise, I'm not sure I would put much effort into troubleshooting.

BandB said:

You could leave it idling and sit in the boat and wait to see how long it will run before it quits, but personally I think that would be sort of dumb to do.

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Yea - can you imagine the guff he'd get if he did it AGAIN?

My engine gets air when my starboard tank gets lower than the lift fuel pump.

Not always but the engine will start and run norfmal, the 5 minutes outside the marina it will sputter and 2X it has died on me.

Tightened everything, next step is try electric fuel pump.

Been chasing it a bit for 2 years.

Xsbank said:

Here you go - read Steve on this topic. Maybe his opinion carries more weight?

The Perils of Chronic Under-Loading | Steve D'Antonio Marine Consulting

Click to expand...

And to add some balance

To me, the easiest way to gauge whether slow speed running is detrimental over years and years of operation is to look at commercial fishing vessels with older designed engines from Detroit, Cat, Cummins, etc… Revisiting the “Detroit” mystique again, its longevity was built on engines rated to run at 1900-2100 RPM and above, but could only last for 30+ yrs when operated continuously at 1100-1600 RPM (again, well under 50% of rated HP)..These same engines in a “crew” boat used in the off-shore oil industry, would go through “top-ends” (or worse) just about yearly when run at close to their governor settings..The longest-lived engines that I’ve been involved with (hrs and yrs wise), have been engines in commercial or recreational trawler type applications run at 50% of rated HP or less.
(snip)
In closing, I’ll mention that although this topic is brought up quite often and many people preach that you’ve got to use a diesel hard if you want it to last, I’m still waiting to find one that was rebuilt before its time due to low speed use..Just the opposite seems to be always the norm.

https://www.sbmar.com/articles/low-speed-running-break-in-of-marine-diesels/

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".The longest-lived engines that I’ve been involved with (hrs and yrs wise), have been engines in commercial or recreational trawler type applications run at 50% of rated HP or less."

What HP an engine is rated to do at WOT has little to do with service life at lower RPM.

Every engine has a graph that shows max power at lower RPM , it might be 215HP at 2100RPM , but down at 1500RPM it could be 100HP.

As long as a substantial percentage of that 100HP is used the engine will live fine.

If only a tiny percentage is used , slobbering becomes possible.

The best way to set up a boat is with a fuel map , the center of the efficiency bullseye is usually the sweet spot.

FF said:

".The longest-lived engines that I’ve been involved with (hrs and yrs wise), have been engines in commercial or recreational trawler type applications run at 50% of rated HP or less."

What HP an engine is rated to do at WOT has little to do with service life at lower RPM.

Every engine has a graph that shows max power at lower RPM , it might be 215HP at 2100RPM , but down at 1500RPM it could be 100HP.

As long as a substantial percentage of that 100HP is used the engine will live fine.

If only a tiny percentage is used , slobbering becomes possible.

The best way to set up a boat is with a fuel map , the center of the efficiency bullseye is usually the sweet spot.

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Actual ex commercial fishing trawler plodding along in the dark now doing 7.5 knots @ 1150 rpm.
That's her sweet spot and probably less than 100 of the 315 horses supposedly available at full noise.

I can't reconcile why JD says my boat engine shouldn't idle longer than five minutes without load while observing railroad locomotives and trucks idling for hours on end.

markpierce said:

I can't reconcile why JD says my boat engine shouldn't idle longer than five minutes without load while observing railroad locomotives and trucks idling for hours on end.

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Exactly.

markpierce said:

I can't reconcile why JD says my boat engine shouldn't idle longer than five minutes without load while observing railroad locomotives and trucks idling for hours on end.

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Damn good question!

koliver said:

My first 1/2 of my boating life was in sail. There, engines don't last at all well. That is primarily due to so many startups being for just long enough to get out of the marina and get the sails up. No chance of getting the temperature up. I know of many sail boats being re-powered. I only know of few power boats being re-powered. It is not a coincidence.

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I did that today with my sailboat. I had to move it from my slip to the guest dock because I can't get out of the slip at low tide. The broker is taking it for a sea trial and survey tomorrow morning. So I started it up, idled in an out of gear for about 20 minutes. Had to back the boat into a tricky spot to tie up. Fortunately, there were some YC members there who were able to take a bow line as the wind was blowing the bow away from the dock.

The engine never really made it to temp and I was going in and out of gear a LOT to get the boat to back in the right direction. It has been too long since I have done that with the sailboat. At this point, it would have been easier with my NP43 with its bow and stern thrusters.

dhays said:

I did that today with my sailboat. I had to move it from my slip to the guest dock because I can't get out of the slip at low tide. The broker is taking it for a sea trial and survey tomorrow morning. So I started it up, idled in an out of gear for about 20 minutes. Had to back the boat into a tricky spot to tie up. Fortunately, there were some YC members there who were able to take a bow line as the wind was blowing the bow away from the dock.

The engine never really made it to temp and I was going in and out of gear a LOT to get the boat to back in the right direction. It has been too long since I have done that with the sailboat. At this point, it would have been easier with my NP43 with its bow and stern thrusters.

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Wifey B: After coming over to our side, you just can't go back.

It does bring up an interesting question. We know lots of powerboaters had sailboats first. I wonder how many the other way around. I would think far smaller percentage who have gone from power to sail.

markpierce said:

I can't reconcile why JD says my boat engine shouldn't idle longer than five minutes without load while observing railroad locomotives and trucks idling for hours on end.

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Its because they soon will be properly loaded which raises exhaust temps to clear the carbon buildup from idling. Now if those same locomotives and trucks were NEVER or rarely loaded, then you would have carbon caused problems at the very least. Those idling engines as I recall seem to smoke more than most boats. Is it from zillions of run hours or cyl glazing. Who knows? For the most part we're all just guessing.

BandB said:

Wifey B: After coming over to our side, you just can't go back.

It does bring up an interesting question. We know lots of powerboaters had sailboats first. I wonder how many the other way around. I would think far smaller percentage who have gone from power to sail.

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Well... You might see a few more in their early years rather than say "over 50" to go from power to sailing. Sailing contains a rather romantic history don't cha know!

For the after 50 group... sailing to power is I believe the main stream for "pleasure" boating.

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.

Xsbank said:

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.

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Regardless, my JD powers an alternator so there is some load even if the propeller shaft isn't turning. How's that different than a locomotive producing some electricity too? ... On the other hand, I can see a difference from idling a cold engine as opposed to a fully-heated engine.

As for idling....

We really need to get the engine up to temp to burn off carbon and water deposits. And that can easily be done in the 40% of power range.

But what probably would be harmful, if one idled the boat for a long time, perhaps to charge up a battery, and then shut down and never got up to temp. Then you still have all that crap in the engine.

Seevee said:

Had a strange thing happen last night.

Started the boat, like I have many times before, and often let it idle for a bit. This time went back into the house to help the Admiral get ready and that took an hour.... she couldn't decide what to wear.

When I got back to the boat, the engine had quit. I had all the electronics on, so I started the genny to add a little charge to the battery and a bit later started the engine. Ran fine. Nothing seemed wrong.

Ran it for a short run, about 15 min. Shut down for a few hours, started up again for another 15 min run and everything was fine.

Just wondering what caused it to quit.

Usually it's a fuel problem, but apparently not, as it ran fine again and the genny ran without a hitch. Spec of water? Don't know.

Thoughts?

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What model motor? Specifically, what happens when you shut down the motor? Does a solenoid turn on, turn off, or mechanical fuel off or ??

diver dave said:

What model motor? Specifically, what happens when you shut down the motor? Does a solenoid turn on, turn off, or mechanical fuel off or ??

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Diver Dave,

It's a Yanmar 6LYA STP, 370 hp., electronic controls. There's a magnetic switch on the starter that starts it when the switch is closed. The engine is stopped wit a solenoid that turns off fuel flow when the stop switch is closed.

Seevee said:

Diver Dave,

The engine is stopped wit a solenoid that turns off fuel flow when the stop switch is closed.

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This engine does have an "emergency stop" button, different from the normal "engine stop" control.

Of course, being an electronic engine, it will have diagnostic codes that are readable over the CAN bus. I'm looking at the ECS manual now, and it may log the "emergency stop" command. Not sure if it is "sticky" though.

I suppose where I am going with this is it may be worth checking some easy stuff, since you don't want "uncommanded stops" when underway. A number of connections and electronic sensors need to work the keep this engine spinning.

diver dave said:

This engine does have an "emergency stop" button, different from the normal "engine stop" control.

Of course, being an electronic engine, it will have diagnostic codes that are readable over the CAN bus. I'm looking at the ECS manual now, and it may log the "emergency stop" command. Not sure if it is "sticky" though.

I suppose where I am going with this is it may be worth checking some easy stuff, since you don't want "uncommanded stops" when underway. A number of connections and electronic sensors need to work the keep this engine spinning.

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Thanks Diver Dave,

I've had the "auto stop" stuff fail engines on other boats but not diesels. The only emergency stop that I know of is if the fire extinguisher is activated. At least there's no manual one. Will look at the manual again on that one.