Running engine w no load

Eric--- Buick has been the most popular brand in China for decades. We have some footage of early CAAC operations shortly after Mao & Co. pushed the nationalist off the mainland to Taiwan. A bunch of nationalist pilots defected to Mao and brought their C-47s with them to form the PRC's initial airline (CAAC). In the film officials are being driven up to the planes in..... Buicks.

Today while the Chinese drive everything from BMWs to Citroens to Range Rovers to Ferraris, Buick is still extremely popular. They have models over there, including a really good looking, streamlined 4-door and several sizes of van, that we don't have in the US.

Marin said:

Eric--- Buick has been the most popular brand in China for decades. We have some footage of early CAAC operations shortly after Mao & Co. pushed the nationalist off the mainland to Taiwan. A bunch of nationalist pilots defected to Mao and brought their C-47s with them to form the PRC's initial airline (CAAC). In the film officials are being driven up to the planes in..... Buicks.

Today while the Chinese drive everything from BMWs to Citroens to Range Rovers to Ferraris, Buick is still extremely popular. They have models over there, including a really good looking, streamlined 4-door and several sizes of van, that we don't have in the US.

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Speaking bout Buicks:

Early 1970s: From a dealer; I purchased 1966 Buick Wildcat; 425 cid, 325 hp coupe w/buckets and console - Toured U.S. in it for couple years in my very early 20's... out of my own pocket - after selling my 1st business; a restaurant and tavern in Maine I started building at 18 yrs inside a seven years abandoned kids garment factory and sold my 51% at 20. Eventually, that Wildcat had seen its day. I parked it down a secluded wooded road. It was assaulted by a bunch of wild kids - they truly totaled it! I mean seats were ripped, all glass broken, lights smashed out, interior door panels stove in, dents in the doors, quarter panels, hood and trunk. Even the 4bbl carb had been smashed with a big rock. I don't know where they ever got the energy for all that - show-offs being drunk I guess. I finally tracked down the two leaders (had been four of them). Parents had them pay it off by working for me in my masonry and concrete const co. They were not really bad kids - just did a dumb/wrong thing!

Sept 1998: From original owner/estate; I purchased 1967 Buick Wildcat; domed heads, 430 cid, 360 hp, 10.5 to 1 comp ratio, a 4 door sedan w/bench seat and cold AC - all electric accessories, 72,321 miles. 121,342 mi as of yesterday. She's still all orig except I added 2" i.d. duel Flowmasters exhausts with pressure equalizer crossover pipe. Sunday driver for me, Admiral, and our grand kids while they’re still young enough to want to hang out with us! This 430 1967 engine is way more powerful than the 66 425. When driving “Cat” by myself, I like to play with the BMWs, Mercedes, and other sporty cars. My solid color “Arctic White” land yacht can really get it on... especially at 70 to 100+ mph hwy speeds, her 430 engine loves to perform at high rpm. Can also drop 100’ rubber from stand still. At 4,400 lbs she still clocks 6.9 seconds 0 to 60. I call her my Luxury Muscle Car! Yeah Baby!

Gets pointed at and mentioned nearly every place we go.

Classic Buick Wildcat is a Fun, Fast, and Comfortable Car!

But, be prepared to pay for plenty of high test gas!

I keep clicking back on this thread hoping to see something about boats. Mods, can you split this one too?

OK Cal,
Running an engine w no load is an extreme version of running an engine w a light load. It's all a matter of how long you run a diesel w a low enough load to force the engine to run w it's lube oil, piston, valves and other vital parts at too low a temperature.

Extreme cases like trucks running all night are probably offset by running up 3000' mountain pass at a 10% grade ... at gross weight. We trawler people never do that so we should be more concerned about light loading, idling and no load running.

I think if Eric and Marin are done discussing cars, there is no need to split this thread, it has stayed true to the original post fairly well. Guys..?

Peter B said:

I think if Eric and Marin are done discussing cars, there is no need to split this thread, it has stayed true to the original post fairly well. Guys..?

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Yep. More boats, less Buicks.

Back in the 60's when GM built a motor home chassis with all the GM engines to select they chose the Olds.

The 403 and 455 were the best heavy duty engines they then made , and the use of the 455 goes on in ski boats 40 -50 years later.

Improvements in engines does continue , so today a 305 or 350 crate engine could deliver the cruise HP of the old big blocks with far better efficiency .

Most only cruised at 10 GPH per engine , 100 HP then , about 130-140HP today.

manyboats said:

OK Cal,


Extreme cases like trucks running all night are probably offset by running up 3000' mountain pass at a 10% grade ... at gross weight. We trawler people never do that so we should be more concerned about light loading, idling and no load running.

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You/us trawler people do that virtually every time you put the boat in gear, especially as you approach hull speed; a boat is always running "up hill". The truck also has a bunch of gears designed to keep the load on the engine consistent.

caltexflanc said:

You/us trawler people do that virtually every time you put the boat in gear, especially as you approach hull speed; a boat is always running "up hill". The truck also has a bunch of gears designed to keep the load on the engine consistent.

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Truck engines experience many abrupt changes of rpm and therefore stress due to often speed changes in regard to speed limits and ensuing gear selections, road angles (up or down or flat) and weights encountered per load hauled. Whereas, boat engines, for the most part, are set at one (the same) speed/rpm with virtually same load for hours upon hours while cruising in fairly calm waters. Only in tall, confused seas do boat engines experience abrupt load/rpm alterations and stress. Durations of 5 mph canal speed as well as idle time are minimal in regard to overall hours of use.

FF said:

"Diesel engines can idle for hours on end with no adverse effects other than burnt fuel".

The independiant operators in the OTR industry would disagree with you.

And yet some of the biggest offenders who waste fuel are independent owner operators.....

In the "old days" the engines would idle all night providing heat or air cond and electric power for an inverter.

In many cases they still do...

Fuel costs (and the air police) made an APU a less costly way to operate overnight.

This is true...any yet the weirdos on the left coast in CA even got pissy about APU's, unless they met their special standard.

Fewer oil changes (done on testing) and about 40% more miles between overhauls has delighted them.

Cummins has been approving a 28,000 mile oil change regimen for new engines for years now.

"no adverse effects "

If cylinder glazing and burnishing, rings sticking, lower compression and more blow-by contaminating the oil is not adverse , I don't know what is!

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Never had a problem with any of that...as the engines in the tractors (semi) that I drove were running well and not using much oil between changes and we put 750,000 miles on our engines before we sold the tractors.... I'm experienced with Cummins N-14's, N-14E's, ISM's, M-11's, Cat C-16's, DD-60's.... I ran coast to coast, flats, mountains, you name it. Pulled dry vans and chemical tankers almost always running at over 79,000 lbs.... 20 years of it. Retired now!!

"In the "old days" the engines would idle all night providing heat or air cond and electric power for an inverter".

Exactly ... they ran all night with a heavy load. Not quite the same as running with no load

boatpoker said:

"In the "old days" the engines would idle all night providing heat or air cond and electric power for an inverter".

Exactly ... they ran all night with a heavy load. Not quite the same as running with no load

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That big engine? What do they aircondition and power, a stadium?

The reefer units that freeze a whole trailer only have a small 4 cylinder diesel.

I'm thinking that cooling the cab, and running a small fridge and TV, would be NO load. HeatIng is definitely NO load.

Where I live, there are times of the year you keep the engine running, unless you have someplace to plug the block heater in.

"In the "old days" the engines would idle all night providing heat or air cond and electric power for an inverter".

Exactly ... they ran all night with a heavy load. Not quite the same as running with no load


Most air cond are under 10 hp of load , hardly heavy for a 400 HP rated engine.

FF said:

"In the "old days" the engines would idle all night providing heat or air cond and electric power for an inverter".

Exactly ... they ran all night with a heavy load. Not quite the same as running with no load


Most air cond are under 10 hp of load , hardly heavy for a 400 HP rated engine.

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Ummm, I think you reversed yourself....

The biggest problem nowadays with excessive idling....particularly with the diesels that hve "EGR" valves on them it seems to accelerate the gumming up of the EGR....which then leads to turbo failure.

We ran M-11 Cummins with and without EGR's for hours at idle running a PTO pump to off load chemicals....and sometimes to load... The amount of load placed on the engine when the PTO was engaged...was not noticeable.

The biggest issue now with idling whether you drive as a fleet driver or owner operator...is the cost of fuel....

75 posts later what I do not understand is most of these boats have been around for 20 to 30+ years with the original power plant. By and large most re-powers are done by owners with the money to want a modern lump in the keel, not an owner that experienced a catastrophic failure. The previous owners had no internet forums telling them about the hazards of under loading diesel engines, yet the motors survived just fine in spite of it. Many here have over 3,000 hours on engines that could very well have been chronically under loaded their entire life for all we know and yet they run fine today.

Could this kinda be like the dino/synthetic debate in that there is no right answer? Just maybe one slightly righter than the other depending upon variables. Not trying to imply under loading is a good thing, just trying to understand where all the catastrophic failures are from under loading. Are there some broken blocks and cranks that we can point at?

I've read Tony Athens take on engine loading and it seems to be up at the upper end toward over loading that causes the failures on higher performance diesel engines. Unless I've completely missed the point, idling and low loads are not traditionally the engine killers.

CPseudonym said:

Many here have over 3,000 hours on engines that could very well have been chronically under loaded their entire life for all we know and yet they run fine today.

Could this kinda be like the dino/synthetic debate in that there is no right answer?

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Personally, I think you are right on the money. Internet forums like this allow people to armchair theory things to death and get totally wrapped around the axle on issues and details that make absolutely no difference to reality.

The second boat I fished on in Hawaii in the later 70s was a 32' custom-built fishboat (made by a builder in Seattle) and powered with a Volvo Penta turbocharged, aftercooled diesel. That engine ran at low trolling speeds (perhaps 4 or 5 knots) for hour after hour, day after day, month after month, and the owner kept running it for years after I left the state in 1979.

In the late 90s while in Honolulu on a Boeing project I looked him up (he now runs a small longline tuna fleet and an ice plant that supplies most of the state with party and block ice). I asked him about the boat we used to fish on, and he said he used it a bunch of more years after I left in the same way. Never had any problem whatsoever with the engine, which is one reason when he started having his longline boats built he specified Volvo diesels.

I've had no experience with the newer generation electronically controlled diesels, although their sophisticated control systems probably make it even easier to run them at slow speeds for long periods without detrimental effects. But on the old generation engines like the Lehman, Perkins, etc, I completely agree with CP. Operate them intelligently per the builder's manual, service and maintain them properly, and they will do the 12,000 to 14,000 hours in recreational boat service they built their reputation on, a reputation that was created in reality long before synthetic oil or anyone gave a rat's butt about loading as long as it wasn't totally over or under-done.

In short, I think much of this kind of discussion these days is -- as Bill S. put it in the late 1500s-- Much Ado About Nothing. If any of it held any water, the 30 and 40 and older year-old engines in all sorts of boats today would have died decades ago. But they didn't and they continue to give good service today.

CPseudonym said:

75 posts later what I do not understand is most of these boats have been around for 20 to 30+ years with the original power plant. By and large most re-powers are done by owners with the money to want a modern lump in the keel, not an owner that experienced a catastrophic failure. The previous owners had no internet forums telling them about the hazards of under loading diesel engines, yet the motors survived just fine in spite of it. Many here have over 3,000 hours on engines that could very well have been chronically under loaded their entire life for all we know and yet they run fine today.

Could this kinda be like the dino/synthetic debate in that there is no right answer? Just maybe one slightly righter than the other depending upon variables. Not trying to imply under loading is a good thing, just trying to understand where all the catastrophic failures are from under loading. Are there some broken blocks and cranks that we can point at?


I've read Tony Athens take on engine loading and it seems to be up at the upper end toward over loading that causes the failures on higher performance diesel engines. Unless I've completely missed the point, idling and low loads are not traditionally the engine killers.

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Big big difference between idling at no load and running at low load. I had my engines surveyed by one of the premier Detroit guys on the east coast. During the sea trial portion, I'd go down to the engine rooms now and then to check on him. At one point when we were coming back in at about 800 rpm, I asked him about running them that slow. He said at that speed "they'll outlast all of us". So asked him, "well then, how long am I going to live?". The #1 caution he had about running them? Don't idle them for more than a few minutes at no load and not up to operating temp. Never found a qualified person who disagreed with that. You could look it up.

Those prior owners were lucky in that they didn't have internet forums feeding them lots of bad information and hearsay, just a few gossipers at the boat club at worst.

I tend to agree about the idling thing, but that's not what's being talked about here, I don't think. The issue is underloading. By some people's calculations, we are severely underloading our two FL120s by running them at a cruise rpm of 1630. These engines are currently 40 years old, have been run by at least the previous owner at cruise rpm of 1500 to 1700 (according to his records).

Today, 14 years after we bought the boat, the engines use less than 1 quart of oil every 100-150 hours, don't smoke, don't fart unburned fuel out the exhaust except at cold startup, and start immediately.

So my guess is that our engines did not read all the posts about the horrors of "underloading" diesels in a boat, or if they did, they just laughed and said, "What a bunch of crap."

These engines are very smart, by the way, so I can imagine them having that conversation. For example, they both quit (on their own) if we try to take the boat south of Anacortes. I guess they feel we're threatening to take them back to California if we do that. So they both stop and won't re-start until we can somehow get the bow back around to point north, at which point they happily fire right up.

Earlier folks where talking about making sure you tossed the lines and started moving as soon as you fired the engine. The fear amounted to any idling exceeding a few minutes was detrimental to engine life. I just don't see it.

Marin's engines certainly don't bear that out. I see the idle thing all over California right now for smog emission purposes with construction equipment by folks who can give a crap about longevity of the power plant.

In my mind if the factory set the low idle speed at X, the engine should run just fine at whatever X happens to be. Otherwise someone explain to me where Nordhaven gets all their passagmaking range charts from considering they are running engines in gear just above low idle speed to get that range. There should be Nordhavens and Krogens everywhere getting re-powered because their owners crossed oceans at low load/speed settings.

Whoaaaa...nellie... let's not confuse things here...

First...those that said cast off and get moving...at least me said that "warming up" in the slip is a myth...nothing about idling....you can start, cast off and by the time you hit open water you can come up to cruise...just not full power.

As to idling...ANY load at the appropriate rpm is OK after an engine is broken in. What's NOT OK is a genset with the governor set to run at 1800 RPM at no load at all hour after hour is what is probably bad for it. A main...once started and starting to warm to a propotional load is fine once past normal breakin periods.

Marin said:

I tend to agree about the idling thing, but that's not what's being talked about here, I don't think. The issue is underloading.

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Gee whiz, I must be reading the thread title all wrong "Running engine w no load" Maybe it's that w without the slash that is throwing me off?

CP: you seem to not understand the difference between being at idle (or any other speed) with NO load and running in gear at idle speed. I will make this way over simplified: The issue really boils down to the engine moving, but the parts not being up to temp. They are designed to be run at a certain temp, that is, all the parts fit together properly thereby work properly when at the appropriate temperature. That is why it causes needless wear and tear, as well as other issues on the engine to run it cold. Yes, problems arise when you idle it for a long time with NO load once it has reached temp, as eventually temp comes down to an unacceptable level. There is way more to it than that, but first you need to grasp the basics of what all that metal is doing. Have a really good mechanic explain it to you some time.

Craig your point is well taken and made many times before. Our engines aren't going to die from idling or even idling quite a lot. No problem as long as the engine is run at about 50% load most of the time and maybe even less as many do here on TF.

But I don't think John Deere's recommendation to minimize idling should be completely discarded either. Lots of idling is not "good" for the engine like lots of sugar isn't good for people but lots of people ingest lots and lots of sugar over long periods of time and they do drop dead prematurely all the time but it's rare for sugar to kill people 30 or 40 years old. Since we don't run our engines close to their upper limits of running time we rarely see the negative effects of idling or underloading unless it gets so severe glazing results.

So for all practical purposes we can, generally, just forget about it.

caltex has got you there Marin. "No load" is no load. But at 1500rpm there is the not totally insignificant load of spinning the engine that fast. To increase rpm more more fuel needs to be injected and more work needs to be done. So the load is small (very small) so I think no load on this thread would be out of gear at any rpm.

But if I was the subject of post # 82 I'd be very offended.

Eric, do you understand the difference between running the engine at idle with no load and running it in idle while in gear?

I understand the metallurgy and the thermal expansion rates just fine. It's the claims of running under X% load that are not making sense to me. One poster early in this thread was claiming he never saw an engine reach rated temperature without a 65 - 70% load with a thermal imaging camera.

George, you said yourself that your mechanic stated while comming into the marina at 800 rpm the engines would outlive you if ran at that speed constantly. I hardly think 800 rpm represents even thirty percent load on your Detroits. The mechanic analyzing them thought they where fine.

Psneeld I perhaps misremembered your line about the warm up period and I agree with what you wrote above. Whoever would run a genny for hours on end with no load at all has more money than brains in my book.

I suppose what has me confused are those that feel idling, even for a half hour or so is detrimental to engine life. Burns fuel but there is more damage from over loading IMO.

caltexflanc said:

Gee whiz, I must be reading the thread title all wrong "Running engine w no load" Maybe it's that w without the slash that is throwing me off?

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I went back and looked at the original post and you're absolutely correct. The topic is no load at all although it did not seem to specify no load at idle or no load at any rpm or both.

But more recent posts had gotten into the topic of underloading underway, so I got the impression the thread had wandered off in that direction.

cal,
Yes ... in gear there is a steady torsional resistance applied to the crankshaft from the prop and delivered to the crankshaft via drive train.
Out of gear the resistance is relatively smooth frictional resistance and the torsional sharp pulses of resistance from compression and power strokes that comprise the bulk of torsional vibration.

Craig wrote;

"I suppose what has me confused are those that feel idling, even for a half hour or so is detrimental to engine life. Burns fuel but there is more damage from over loading IMO."

Just like refined sugar is detrimental to your life.
I thought it was a pretty good analogy Tom.

CPseudonym said:

....
Whoever would run a genny for hours on end with no load at all has more money than brains in my book...

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Or forgetful/distracted. My Onan genset manual says run it 5 minutes, no load, before closing down after use, to reduce temp. I use a kitchen timer kept at the helm. With main engines running and operating the boat, I easily forget.
There`s a tip, and an instance to run no load.

Can smell the aroma of diesel fuel and exhaust!

And, know that I'm in a pretty much diesel-only thread...

But, I Simply Gotta Ask: For delta, bay, close costal, and even some off shore cruising with a pinch of blue water jaunts... what the heck is the matter with utilizing really good performing gasoline engines??

Gas engines are simple/easy/inexpensive to maintain or repair, clean burning and mostly odor free, reliable, cost effective, and quiet for powering self contained cruiser-boats; trawler design - or otherwise. And, when traveling at hull speed or below good gas engines can be darn economical in using fuel. New, high tech gas engines are getting right in line with diesel engines regarding fuel economy.

Yeah, I know - - > Yada, Yada, Yada... You run risk of blowing sky high from gas fume explosion; but, that simply ain't a gonna happen if the boat is equipped/vented correctly with all gas tanks/lines in good condition and the Captain is carefully looking after what's going on. I will admit - there is a very slight chance some numb-skull fills an area with gasoline fumes and somehow ignition occurrs, then a BOOM will happen. But those things are always averted on a good Captain's boat! At least that's how I see it!

Oh and to dispel another item - - > Carefully maintained, gently used, high quality gas engines can run well for several thousand hours; 4,000 + hrs is not unheard of. And, although gas engines may need replacement anywhere from 2 X to 5 X as often as various diesel makes/models, the cost of gas engine replacement is pennies and the hassle is limited in comparison.

Now, I’m not saying that I won’t again own a boat with diesel and not saying that diesel is overrated, nor am I saying that diesel is not a required power source once a craft gets past a certain length and weight, cause it is! I’m just saying that gasoline engines in small to mid sized (28’ to 45’) pleasure cruisers ain’t a bad way to go!

Simple Is as Simple Does!

Art said:

But, I Simply Gotta Ask: For delta, bay, close costal, and even some off shore cruising with a pinch of blue water jaunts... what the heck is the matter with utilizing really good performing gasoline engines??

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It's simple, Art. Gasoline engines are really, really, REALLY boring. Anyone, even my dog, can run a gasoline engine and fix it. They convey no status whatsoever upon the owner. Soccer moms operate gasoline engines. Teenage kids with 0.8 grade point averages operate gas engines. When someone says they have gas engines in their boat, the unspoken questions other boaters immediately have are, "What, you couldn't afford a diesel?" "You afraid of diesels?" "Are you that dumb that you can't figure out how to operate a diesel?" And so on.

To paraphrase the comedian Gallagher, gasoline engines have no Style. They simply aren't cool.

When a boater talking to other boaters on the dock says, "I have a gas boat," you'll notice the other boaters wander off or start talking amongst themselves about the weather or they suddenly remember they have to see a guy about a horse.

A cruising boat with gas engines just isn't a cruising boat. It's a wannabe boat.

Now Bob Tollefson was well aware of this but back in 1936 when he got started diesel engines were big heavy scary things that didn't lend themselves to recreational boats or boat owners very well. And he knew his market didn't want to screw with something they didn't understand. So he used gas engines like many of his contemporaries.

But as diesels became smaller and lighter and less expensive and easier to deal with the boat folks took notice. American Marine put diesels in their then-new line of Grand Banks boats in 1966 and coined the marketing phrase "Dependable Diesel Cruisers." Across the way at Kong & Halverson, they did the same thing with their Island Gypsy line. And on it went.

Gas boats became the toys of the go-fast boys, water skiers, and whatnot. The no-substance crowd, if you will.

And since serious boats (even the newerTollycrafts) soon all sported diesels, it followed that diesel became synonymous with "serious boat." As opposed to Bayliner and Sea Ray runabouts and such.

So you see, Art, there is nothing operationally detrimental about having a cruising boat with gas engines in it. It will go all the places the diesel boats will. But unlike the operators of diesel boats, there is simply no way to operate a gas cruising boat and have anyone take you seriously. Or think you're cool.

You'll just be a guy who had to "settle" for a gas boat because for whatever reason you couldn't swing a diesel boat.

I feel sorry for them, I really do. Sometimes I think there should be one of those worldwide funds, like the Save the Children funds with their tear-jerking informercials, set up to help the unfortunate owners of gas cruising boats. After all, they're just victims, right? It's not their fault they lacked the foresight, the means, and the sense of dignity and class to get a diesel boat. Perhaps they didn't choose gas. Perhaps it was thrust upon them by unfortunate circumstances. A broken home, lousy education, possibly even gang influence could send a youngster down the road to gas and the ultimate humiliation and disgrace he faces later as an adult in a diesel world.

I can only speculate, however. You'd need a whole battery of phychologists to answer your question in something approaching a meaningful way.