Diesel Engines: To Run or not to run, that is the question

[dcharna]

All,

I have heard conflicting views on whether to run my engines in the slip to warm them when we can't get out. We launched around April 4th and the weather has been *&^%$. Would you run your engines and if so, how often.

Thanks,

Dan

 

[ImpulseIII]

Diesels typically do not warm up unless under load. Just letting them idle in the slip accomplishes nothing other than burning fuel. I start 'um if I am going out, otherwise they stay off.
Just my $.02...others may have different approaches.

 

[Lord Farringdon]

You're right, they don't warm up well in idle. Increasing rpm helps but still they aren't under load and as such temps don't reach a good operating temperature. I run my engine for 5 mins at idle, 20 mins at 1800 rpm and then another 5 mins at idle before shutdown. The temp gets close to the cool end of the operating temperature range but doesn't quite reach it.

I start and run at idle to ensure the turbo gets plenty of oil in those first few minutes after start. The remainder of the time at 1800 rpm is just to get some warmth into the engine, the 5 min at idle is just to ensure the turbo cools down well enough to avoid any oil glazing/varnish on the bearing surfaces which would otherwise eventually reduce oil flow.

The real reason I run the engine is to splatter oil around the place every two weeks if I don't otherwise take the boat out. A diesel is a big block of cold metal and it condenses water vapour in the air very well. Diurnal temperature changes can draw water/salt laden air into the cylinders through open valves and this condenses very quickly on the cylinder walls which may not have a lot of oil left on them if the engine hasn't been turned in a while. This allows corrosion of the linings to occur and you can imagine the wear that occurs during the first few strokes after start on an engine that hasn't been run for a few months. When I check my oil level after a two week absence from the boat, It's not unusual to see condensed water droplets on the dipstick above the oil level.

For boats that are regularly used throughout the year, this is not an issue. I don't imagine this would be too much of an issue for boats in Florida either since everything is normally warm and dry I guess? And, I guess if the engine is inhibitied and the hull wrapped for winter storage that's not a problem either. But, for a boat sitting out in the open in a marina all year and having periods of non-use, regular engine running drys the exterior and interior of the engine and removes any residual dampness and keeps the working parts well oiled and free of corrosion. If you own a gun, you will (should) regulary oil it and work the action for the same reason.

All IMHO of course but I note at my marina there are alot of guys running their engines when the weather has prevented any sailings for a while.

Terry

 

[Alex F]

All,

I have heard conflicting views on whether to run my engines in the slip to warm them when we can't get out. We launched around April 4th and the weather has been *&^%$. Would you run your engines and if so, how often.

Thanks,

Dan

In the areas with warmer climate (SC, FL, etc.) marinas or 3rd party vendors offer a service where a captain or mechanic comes to the boat and runs all the systems, this includes mains and generator. This service is highly used by folks who live in remote location up north and visit/use their boats once in a while. If I recall, the engines and genny are on for about 20min or so. The frequency of this service varies from every two weeks or every month. I'm sure one can arrange any desired schedule. As you can imagine, the point is that there's a very good reason the vital components (mains and genny) are being run on the regular basis. Any diesel mechanic will tell you that diesels don't like to sit without running. So, idling in the slip is way much better than not running at all.

Just my .02c FWIW.

 

[ImpulseIII]

What about the diesels and generators that sit idle all winter?

 

[trit21]

I agree with Frank on this one. Diesels do not need to be run in the slip. The only reason they offer that service is because it makes them money from owners that don't know any better. I have run my boat in the slip and it does not reach operating temps unless under load. As a matter of fact, turbo doesn't even produce any boost and the EGT's register very little temp when I run it at full RPM in the slip (doing maintenance and troubleshooting).

From what I am told, when you run a diesel at below load for any amount of time, without getting to operating temps, you may glaze the cylinder walls. Same thing when everyone on here talks about running generators with no load, it is bad for it because you have the chance of glazing the cylinder walls.

As far as getting salt laden air in the valves, it has to travel past my turbo, throught the aftercooler, uphill throught the aftercooler as well, and then into the intake and past the valves. And why would it flow that way if nothing i drawing it in? The air inside the engine isn't going anywhere so to replace that air, it has to come out of the cylinders before new salt laden air can travel in. Don't buy it.

IF you don't run it for a couple of months, take it for a cruise and get it under load. Starting in the slip serves no purpose at all unless troubleshooting/repairing/etc.

 

[Lord Farringdon]

I guess we agree to disagee on that one Tom. I note you are in FL which I am not familiar with but all the pictures are of a very warm and dry place. In contrast, our climate can be punctuated by deep depressions and ridges of high pressure sometimes occuring on the same day. Add the high humidity in Auckland, some cool weather and the salt air environment and you have a corrosive mix that can do your engine no good if it is left to sit there particularly over the winter months. When I see condensation on the dip stick and on the outside of the engine, I know the linings are going to be getting that too. "And why would it flow that way if nothing i drawing it in?" Daily changes in air pressure. Not that a few days would make any difference but a few months of continually changing climatic conditions and atmospheric pressure will.

In the end, the benefits of running the engine may be subjective and open to debate but I have never felt uncomfortable doing it. Of course there are always stories that support the opposite view and one that I can recall involves a diesel engine that had laid in a boat on the hard for 10 years and started perfectly first time with nothing more than a change of oil and fuel filters. But I suspect the engine had laid in a warm dry environment.


Terry

 

[sea salt]

Install a pair of engine block or oil pan heaters. That will control the humidity problem in your ER and keep the rust issue at bay.

 

[Alex F]

What about the diesels and generators that sit idle all winter?

Well, this is where we just don't have an option to run them. So, we do what's necessary to preserve the engines to sit for long storage. On the other hand, I know people who keep their boats behind the house and run the systems when temps above freezing.

In my personal opinion getting the lubrication going through the engine components is the primary goal. Turbo is the different story. What about those that run at trolling speed 90% of the time? Granted, when they run at lower RPMs the engines get to the normal temp, but the turbos are not activated until they hit those throttles to 1800RPMs or so.

As with anything, we all have different opinions on things. I hope to learn something new in this discussion.

 

[ImpulseIII]

, I know people who keep their boats behind the house and run the systems when temps above freezing.

.

Why would you do that? Doesn't that suggest you then have to replace the anti freeze and re-winterise?

I guess, regardless of conventional wisdom, (assuming anything conventional can be found here).....I'll just run mine when I feel the need to go out and enjoy the boat, and take the chance of my engines deteriorating due to lack of use.

 

[HUMPH]

Prep your boat for your trip, fire up the engines then untie your lines. Idling out of the marina will lubricate the engine just fine and when you have idled underway for a while you are ready to let her fly. I do like to keep it at 7 or 8 knots until the temp starts coming up.

 

[Turtlesboat]

I run mine in the slip. Keeps the impellers from setting as well as the belts, I figure it may help things like the thermostat, circulates the coolant and oil, gives the starters a spin as well as the alternators. Maybe it's voodoo, maybe it's not. We also cruise with a Santa Rita on the boat, just in case.

 

[melida]

You're right, they don't warm up well in idle. Increasing rpm helps but still they aren't under load and as such temps don't reach a good operating temperature. I run my engine for 5 mins at idle, 20 mins at 1800 rpm and then another 5 mins at idle before shutdown. The temp gets close to the cool end of the operating temperature range but doesn't quite reach it.

I start and run at idle to ensure the turbo gets plenty of oil in those first few minutes after start. The remainder of the time at 1800 rpm is just to get some warmth into the engine, the 5 min at idle is just to ensure the turbo cools down well enough to avoid any oil glazing/varnish on the bearing surfaces which would otherwise eventually reduce oil flow.

The real reason I run the engine is to splatter oil around the place every two weeks if I don't otherwise take the boat out. A diesel is a big block of cold metal and it condenses water vapour in the air very well. Diurnal temperature changes can draw water/salt laden air into the cylinders through open valves and this condenses very quickly on the cylinder walls which may not have a lot of oil left on them if the engine hasn't been turned in a while. This allows corrosion of the linings to occur and you can imagine the wear that occurs during the first few strokes after start on an engine that hasn't been run for a few months. When I check my oil level after a two week absence from the boat, It's not unusual to see condensed water droplets on the dipstick above the oil level.

For boats that are regularly used throughout the year, this is not an issue. I don't imagine this would be too much of an issue for boats in Florida either since everything is normally warm and dry I guess? And, I guess if the engine is inhibitied and the hull wrapped for winter storage that's not a problem either. But, for a boat sitting out in the open in a marina all year and having periods of non-use, regular engine running drys the exterior and interior of the engine and removes any residual dampness and keeps the working parts well oiled and free of corrosion. If you own a gun, you will (should) regulary oil it and work the action for the same reason.

All IMHO of course but I note at my marina there are alot of guys running their engines when the weather has prevented any sailings for a while.

Terry

Terry,
I guess 1800rpm is typo you run to warm your engine.
As you know we have both kompressor and turbo.
Kompressor engages at 1500rpm and then gives the flag to turbo around 2500-2700rpm.
So between this rpm range you must not run your engine in extended periods.
To warm and cool down I always run mine at 1450rpm.

On th other side, running the engine at slip in first few minutes is good for checking any leaks of sea water, fuel, coolant, air, alternator and oil pressure. And of course leaks from drive/bellows.

I always start mine with the engine hatch open to check above, then start my electronics, collapse the shore power cable and fenders then untie and leave the slip. These takes 3-5 minutes and after passing the 1/4mile no wake zone at idle engine temp shows 40C then I gradually increase the rpm to 1450. A few minutes later optimum temp reached then I spool up and plane.

 

[mysticowner]

If you can't bring the oil to operating temperature you would be far better off to fire the engine for about 30 seconds to circulate oil and the impeller and shut it down. That sprays around the oil and lubes the cylinders. JMO

 

[Lord Farringdon]

Terry,
I guess 1800rpm is typo you run to warm your engine.
As you know we have both kompressor and turbo.
Kompressor engages at 1500rpm and then gives the flag to turbo around 2500-2700rpm.
So between this rpm range you must not run your engine in extended periods.
To warm and cool down I always run mine at 1450rpm.

Hi Sayat,

Good to hear from you again . My throttle quadrant is a little different to yours but I have to push a button to disengage the engine from the drive so that when I advance the throttle, the engine rpm increases without driving the props. The maximum speed this can go to is 1800 rpm so no typo. As for running between the supercharger (SC) and turbo speeds well, the main problem as I see it is that the SC gets up to about 12000 rpm just before the turbo kicks in at around 2500 to 2700 engine rpm. Running the SC at that speed for long periods is going to generate a lot of heat and may not be too good for the SC. In contrast, running the SC at 1800 engine rpm is not likely to be as much of a problem so far as heat generation is concerned. In fact I wouldn't be surprised to learn that the 1800 max 'out of drive' rpm is based around an acceptable speed for SC running but I am guessing a bit there.


As for the turbo, you can see that with the engine running at 1800 rpm the turbo is running below boost threshold which is normally attained around the 2500-2700 rpm. So the turbo may not be doing any work but it's still spinning ...and fast.

This from Wiki may be interesting too:

"Because turbochargers have high operating temperatures, it is often recommended to let the engine idle for up to three minutes before shutting off the engine if the turbocharger was used shortly before stopping. This gives time to cool the turbo rotating assembly. It also ensures that oil is supplied to the turbocharger while the turbine housing and exhaust manifold are still very hot, otherwise coking of the lubricating oil trapped in the unit may occur when the heat soaks into the bearings, causing rapid bearing wear. Small particles of burnt oil can accumulate and lead to choking the oil supply and failure. This problem is less pronounced in diesel engines, due to specifications of higher-quality oil."

Still, I don't think I'd want to run the engine at 1800 rpm for hours at a time. That might be asking too much of the SC.


Cheers mate

Terry

 

[melida]

Terry,
Glad to hear you again.
I think you don't have the EDC control panel in the below pic. When I press to the N button then move the throttle it advances at idle max. 1500rpm to prohibit the kompressor kick in . Something technically wrong with your settings.

Even at idle when the engine is cold kompressor works to heat up engine quickly. You can feel it to put the lever forward or reverse, kompressor stops since 1500rpm hasn't reached yet.
This is the same principle if you familiar with Kompressor series of Mercedes cars. When you start the engine it runs at 1500rpm app. 1 minute then idles to 600-700rpm then ready to go.

You're right about the turbo and ofcourse what I do is the same for cool down period. Once the turbo spooled up after tied to my berth or anchored I let the engine run for 3-5 minutes to cool better the raw water passed components while they are not working harder.

Take care my friend.

 

[Alex F]

Why would you do that? Doesn't that suggest you then have to replace the anti freeze and re-winterise?....

Frank, I think you know what I meant when I said that they do it when the temps are staying above freezing. The difference is that having the boat behind the house allows folks to have longer boating season and keep the engines decommissioned for much longer. While you and I tuck our boats under shrinkwrap in the last weeks of October or beginning of November, Dom and Rod just winterize their systems and keep the engines decommissioned. While the temps are mild with the help of oil pan heaters and/or boatsafe ER heaters the ER stays above 40 degrees. This allows these guys to run their boat on a nice day or just idle at the dock. Obviously it's all weather dependent, but I think most of the time their engine winterized only for couple of months (Jan and Feb), not like ours 4-5 months.

I run mine in the slip. Keeps the impellers from setting as well as the belts, I figure it may help things like the thermostat, circulates the coolant and oil, gives the starters a spin as well as the alternators....

If I had the boat docked behind my house these are enough reasons to fire up the engines once in a while for 20 min or so. There are just too many components that people are overlooking and those components don't like to sit without moving for a long time.

 

[ImpulseIII]

Didn't know what you meant....and who is Dim?

 

[Alex F]

Typo...correction made.