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-   -   How should you run the engine? (http://www.sailnet.com/forums/diesel/76247-how-should-you-run-engine.html)

Classic30 07-13-2011 08:53 PM

How should you run the engine?
 
Here's a question: I know that all marine diesels need to be run at least every two weeks to (a) minimise the risk of seawater corrosion in the cooling passages and (b) top off the staring batteries. I've also heard that running a marine diesel off-load for long periods of time can coke up the cylinders reducing it's life, so:

Assuming a boat is sitting on it's mooring over a long period of time and never used, ideally, to get the longest life out of engine and batteries, assuming the engine is run at least every 2 weeks, for how long should you run the engine each time, at what load and at what speed?? :confused:

Idle? Above Idle? In gear? Out of gear??

No-one I've spoken to seems to really, definitively, know the answer to this, and yet hopefully there are some diesel experts around here who know the answer. Let's hear it. :)

tdw 07-13-2011 09:18 PM

Cameron my boy , you will worry yourself into an early grave.

Yes its nice if the donk gets a run every couple of weeks but shoot, it will not roll over and play dead if it only happens once a month.

Now its also true that a diesel should only be run under load but if you were to go out and let her run for half an hour every week or so you won't kill it. Of course you could just run it at low revs in reverse and hope your mooring is a goodun. :eek:

Anywho, I thought you were in a pen ?


ps - Ok so we went solar end of large year but you know us. We are out on Raven at least one weekend in two and we'll spend up to eight weeks a year living on board during our mini cruises. Pre solar we would run the dink up to two hours a day to charge house batteries. Sometimes I'd take the opportunity to go for a potter but most times not under load. That lil ol Bukh gets a bit tick from mechanic each year so it cannot have done the thing much harm.

cheers mate, love to the missus. :)

Andrew

RichH 07-13-2011 10:19 PM

With respect to corrosion (iron engine block and iron exhaust manifold), you need the engine to develop full operating temperature (180F/82C) for a period not less than ~1 hour. This will 'convert' the developed destructive ferric (red) rust to 'protective' ferrous (black) rust.

Obviously, you cant look inside an engine's cooling passages to assay the amount of 'red' rust present; so, the advice of 'running the hell of the engine at the earliest opportunity' ... is a good one.
;-)

BarryL 07-13-2011 10:44 PM

huh?
 
Quote:

Originally Posted by Hartley18 (Post 749964)
Here's a question: I know that all marine diesels need to be run at least every two weeks to (a) minimise the risk of seawater corrosion in the cooling passages and (b) top off the staring batteries. I've also heard that running a marine diesel off-load for long periods of time can coke up the cylinders reducing it's life, so:

Where did you hear that? Are you referring to a raw water cooled diesel or a fresh water cooled diesel? Either way, whether the engine is running or not, there will be seawater sitting in the cooling passages. So running the engine won't change that.

You do need to keep the batteries charged, but you don't need to run the engine every other week to do that. You can use solar, shore power, or just let them run down, and bring a jump pack on board in case they get so weak they won't start the engine.

Batteries are a lot cheaper than a new engine!

Quote:

Originally Posted by Hartley18 (Post 749964)
Assuming a boat is sitting on it's mooring over a long period of time and never used, ideally, to get the longest life out of engine and batteries, assuming the engine is run at least every 2 weeks, for how long should you run the engine each time, at what load and at what speed?? :confused:

Idle? Above Idle? In gear? Out of gear??

No-one I've spoken to seems to really, definitively, know the answer to this, and yet hopefully there are some diesel experts around here who know the answer. Let's hear it. :)

If this were my boat (and if I wasn't going to use my boat often enough I would probably just haul it or sell it), I would start the engine once a month, drop the mooring, and motor at 80% power for 15 minutes or so.

Barry

Classic30 07-13-2011 11:47 PM

TD, thanks for your concern, but having seen others do a range of things from Nothing(TM) to Run-the-Engine-for-an-hour-in-the pen-in-gear, I thought it was a question worth asking. No stress here - just curious. :)

I know there might be slight differences between makes/models, but a Diesel is a Diesel and surely there are "best practices" everyone should know.

Quote:

Originally Posted by BarryL (Post 750000)
Where did you hear that? Are you referring to a raw water cooled diesel or a fresh water cooled diesel? Either way, whether the engine is running or not, there will be seawater sitting in the cooling passages. So running the engine won't change that.

Hypothetically speaking? Fresh water cooled. "The engine must be started and warmed up at least once every 14th day while the boat is in the water in order to prevent corrosion." - Volvo MD2010-MD2040 Instruction Book pg 12... or perhaps Volvo don't know what they're taking about?!? :p

...and I suspect is where RichH is coming from, although, to me, it seems it doesn't take an hour for the engine to be "warmed up". Even so, running an engine for ~1 hour every 2 weeks would mean minimum 26 hours/year on the engine. That's still well within the max hours between service intervals. Perhaps that's the "how long" answered then!


The trend thus far seems to be to take the boat out for a spin on a regular basis.. not always possible, but I guess that indicates "run under load". Would that mean that someone doing a circumnavigation, say, would be advised to run their engine in gear whilst charging the batteries - or is an alternator or two now considered to be enough of a "load"?? ;)

tdw 07-14-2011 12:14 AM

Quote:

Originally Posted by Hartley18 (Post 750024)
TD, thanks for your concern, but having seen others do a range of things from Nothing(TM) to Run-the-Engine-for-an-hour-in-the pen-in-gear, I thought it was a question worth asking. No stress here - just curious. :)

I know there might be slight differences between makes/models, but a Diesel is a Diesel and surely there are "best practices" everyone should know.



Hypothetically speaking? Fresh water cooled. "The engine must be started and warmed up at least once every 14th day while the boat is in the water in order to prevent corrosion." - Volvo MD2010-MD2040 Instruction Book pg 12... or perhaps Volvo don't know what they're taking about?!? :p

...and I suspect is where RichH is coming from, although, to me, it seems it doesn't take an hour for the engine to be "warmed up". Even so, running an engine for ~1 hour every 2 weeks would mean minimum 26 hours/year on the engine. That's still well within the max hours between service intervals. Perhaps that's the "how long" answered then!


The trend thus far seems to be to take the boat out for a spin on a regular basis.. not always possible, but I guess that indicates "run under load". Would that mean that someone doing a circumnavigation, say, would be advised to run their engine in gear whilst charging the batteries - or is an alternator or two now considered to be enough of a "load"?? ;)


You've had dealings with Volvo then ? :rolleyes:

I'm not at all sure but just cos the water is warm does not mean full operating temp. I thought that an hour seemed too long but yes probably at least half an hour would be good.

I suspect it takes more than an alternator but I'd love to be proved otherwise.

Classic30 07-14-2011 12:20 AM

Quote:

Originally Posted by tdw (Post 750034)
You've had dealings with Volvo then ? :rolleyes:

On the odd occasion.. and each time I do, my wallet develops this little corrosion hole and all my money leaks out! :eek: :rolleyes:

Quote:

Originally Posted by tdw (Post 750034)
I'm not at all sure but just cos the water is warm does not mean full operating temp. I thought that an hour seemed too long but yes probably at least half an hour would be good.

Good point and, not having a temperature gauge, not something I'd really thought about.

aeventyr60 07-14-2011 12:32 AM

When my boat with a Perkins 4108 is not being used much, I 'll run the engine once a month, I bring it up to operating temperature, then run it in reverse at 1500 rpms for 15 minutes, then run it in forward at 2000 RPMs for another 15 minutes, then 15 minutes to cool down in neutral. Seems to have worked fine for this engine.

tdw 07-14-2011 12:32 AM

Quote:

Originally Posted by Hartley18 (Post 750035)
On the odd occasion.. and each time I do, my wallet develops this little corrosion hole and all my money leaks out! :eek: :rolleyes:



Good point and, not having a temperature gauge, not something I'd really thought about.

No temp gauge ? Wow .... that really was a bodgey instal wasn't it ? I could live without lots of engine geejaws but a temp gauge ? No way.

Classic30 07-14-2011 04:39 AM

Quote:

Originally Posted by tdw (Post 750040)
No temp gauge ? Wow .... that really was a bodgey instal wasn't it ? I could live without lots of engine geejaws but a temp gauge ? No way.

:p :D


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