Should You Exercise The Kids

Can someone show me in an engine manual or manufacturer info where it says to run them at least a couple times a month or any similar info? If your conditions warrant due to bottom growth or other items I can see it but otherwise I see no validity in starting them every other week. There are millions of boats, cars and other internal combustion engines that are winterized and/or not ran for months at a time. Now I'm not talking about letting something for years. As we all know, if it rests, it rusts. But starting every other week? How long do you really think the oil stays up in the engine after you run it? Have you never heard that the most destructive time for an engine is at start up until oil pressure builds? Why keep doing this? What are you gaining?

I agree with you, DM. Does it hurt? No. But I don't see it as a requirement.
So if you live nearby and spend time on the boat, by all means start the boat and run it on occasion. But I don't see it a necessary to hire/recruit someone to do this if the boat will sit for a couple of months. I've been around larger boats with Diesel engines my entire life, and have never once had trouble with an engine that's been sitting idle (in the not running sense, running at idle is really bad for them).

The trouble is that all the information we have is anecdotal and originates in hearsay. Including my advice As Dockmaster says: Where's the documentation?
Some of us have some exposure to running take-out engines in storage that can't be turned over after extended storage as the rings are rusted to the cylinders. There's a thread on that on the gee captain forums that many engineers have weighed in on. That is obviously the extreme, but it illustrates the concern. It's not apples to apples, either, because those kinds of engines don't have exhaust systems attached.
There are many factors involved, starting with the design of the exhaust and how much water remains in the exhaust. Add environmental factors, and that water can saturate the air in the exhaust system to some extent. Capt J points out that some engines he had experience with developed compression issues in some cylinders. Light corrosion on cylinder walls can abrade piston rings. At least some of the "oil" on cylinder walls is diesel fuel, which, evaporates relatively quickly.
Winterization is an apples and oranges scenario, since there should be antifreeze in the exhaust as opposed to salt water. Besides, who doesn't stuff a paint bucket or ball into the exhaust outlets during storage?
As NYCAP asks, how long is a "few months"? Ultimately, there will be open intake and exhaust valves. From my experience and training, I can tell you that certain 4 cylinder engines will stop at one of two places in the rotation, and it's likely similar on engines with more cylinders.. Anyone who has ever replaced a ring gear or flex plate because the starter will do little more than "zing" , knows that the damage on the ring gear is in only one place on the flywheel/flex plate. Shut off engines stop in one place, more often than not, for some reason. Additional reading, for those curious.
Ideally, the engines should have a load, which is why one forward/one reverse is a workable compromise. Ultimately, even idle can't be too bad. Just walk around any truck stop at night, especially in the winter. Many idle for hours, with no more load than the alternator keeping the TV going. It keeps the fuel from gelling and prevents "non start" situations.
Google isn't much help when searching for reliable advice on this, at least not on the first page of hits. I'm not sufficiently invested in this to look further. I tried "running diesel engines periodically" and came up with a bunch of myth-buster stories in magazines, that didn't touch on the issue.

I'm not a mechanic. I only know what I've been taught by those who came before me, and that is that an engine that sits idle for long periods develops corrosion because the pistons and cams don't stay lubricated and the only way for them to stay lubricated is to run them. I think the trucks idling in the rest stops is more so they don't lose prime after running hot for many hours than to keep them lubricated. How long does oil coating last after shut down? I DK, but not forever. As for winter layup, don't most engines get fogged as part of the winterization process?

Gas engines get fogged. Diesel engines do not.

Thank you. Wasn't sure. I've winterized many gas motors but the diesels were always left to the yard. What if anything do they do to protect the cylinders, etc. on diesels?

I don’t think the comparison to trucks at a truck stop is relevant. Most of those are running for heat, A/C or power inverters.
Again, my point was not about engines sitting for very long periods where rings adhere to cylinders. I was referring to the OP’s reference to a few months, maybe a bit more for longer winters. Seems silly to me to hire someone to start engines every other week. I think you run higher risk of the hired hand causing damage then from the engines sitting a few months.

Personally, I have never seen harm in exercising a marine diesel engine. Especially if the boat is planned to remain dormant a few months. Starting and running the main engines a few minutes monthly gives a you good overall on how the boat is operating as a whole, even if only dockside and testing gears / steering. You should also take the opportunity to check other systems and their functionality(not a bad idea for a laid up boat either).

Bit of experience from a different application but I feel this relates. While on trans Atlantic passages to the Med on any yacht we would have our cruising RPM for what was normally 10-15 days continuous run time(Many factors determining run time). Our RPM for 2500NM + voyages was generally different to short Caribbean jumps. Reduced by more than couple hundred RPM most of the time. If our distance to be covered exceeded 72HRs I would implicate increasing main engine RPM to 80% load for 20 minutes once a day. This was an effort to move the engines/gearboxes through RPM range during the pro longed lower RPM crossing period. Sometimes the exercise lasted longer than 20 minutes. Having not done that for 10-15 days continuous, 1000RPM, on a CAT3512 can have negative impacts over time.

As suggested previously, you are not creating more problems by starting and checking your equipment on a monthly or bi weekly basis. If anything it could alert you to a new issue that may have been a developing problem months/years! I've seen plenty of dockside beauty's go to leave port only to discover a maneuverability issue in the most precarious navigational situation, then disaster. Check your gear!

The question never answered is "what is a few months?" If it's only one or two months, I would have someone checking on the boat unless I had cameras and gauges but I wouldn't have them run it. However, if it's six months, I would have a professional run it periodically and check other systems so I would return to a boat ready to go, not to one with a myriad of issues needing to be addressed. My personal cut off point would be 2 months but I wouldn't argue with 3.

Our only experience in this regard was leaving a boat on Lake Pickwick over a winter. We could monitor vital signs and had many cameras we could check remotely. Still, every 4 to 6 weeks, we flew two people there and they took it out and ran it for several hours, serviced it, made sure all was good, then they flew back home. That was extreme and we probably could have just paid the marina to run it a little at the dock, but we wanted to check it and run it ourselves as we didn't have any experience with anyone there.

H

Hopefully we're not talking about a "hired hand", but someone who knows boats. On boats I checked it started by observing the lines and waterline, and for signs of damage or break in. Then a check of the interior, fridge, a/c, flushing toilets, engine room check, then firing up and bringing up to temp. On the boats I checked I also took them off the dock and brought them up on plan before putting her back to bed. All told about 1 hour aboard. I've got a little more experience than a "hired hand" though. Who you have will certainly determine how much you have checked though. I wouldn't hire some kid and give him the keys to my boat much less the ignition keys. I had one boat I came to and found the windshield smashed. Turned out a sea gull was dropping clams to crack them open. Needless to say I definitely don't recommend walking away and trusting to luck for a few months.

For seasonal lay-ups, ie.. November to April, we don't do anything to diesels except fill the raw water side with anti-freeze.

I have been doing the that plus oil change right before hauling out

Yes, I do that too although don't really consider it "winterization". Just annual service that it makes sense to do right before lay-up.

I will also say that, having watched multiple seasons of Goldrush which makes me an expert on diesels, I don't think they do anything their heavy equipment over the long winter other than turn off the key and watch the snow pile up!

Changing the oil, I've also understood, was important because it removes the acidic, ash heavy used oil

When you park your disc brake equipped car for a few weeks you will notice surface rust building up on the discs. That is what happens in the compression chambers of the cylinders with open valves and open exhaust. Internal rust and sea water laying in coolers are not your friend. Hauled or not the sea water side should be flushed with fresh water, block heaters on and in a perfect world stick a soccer ball in the exhaust.

That's a good point and I agree with you. 2-3 months is a good "cut off point". About your experience at Lake Pickwick with your boat. Maybe it had been better to pay someone there to do the job. Flying two people there every 4 to 6 weeks to make the service and check is a possibility but maybe not the easiest one

It's very important in a boat. Everytime the boat rocks, or in your case steps on the gunnel to get on the boat, water rushes in the exhaust (or out and back in) and forces humid air in and out of the open cylinders. The same with boats that sit where there's a lot of current. I literally came across a boat with a dead cylinder on each engine and only 300 engine hours because of this very same situation. Oil sits on things for a while......but it also helps get any moisture out of the valve cover area and stuff like that.......everything gets worked.....(impellors, injectors, etc.).....seals get moved.......you find if something is failing.

In boats for sale that I've been involved with and the engines weren't run on a regular basis and sat for a few months as the vessel was for sale, you can always tell in the oil samples as they're always higher in iron......(and other metals) even if the oil change was within a year.