Run the Engines or Don't Run the Engines?

S

shadow9999

Member
Nov 23, 2009
110
NJ and FL
Boat Info
Viking Sport Cruiser 50
Engines
Volvo D12's
My boat is powered by pair of Volvo D12´s. I use the boat in New Jersey and the surrounding area in the summer and down in south west Florida in the winter. So the boat is used year round. I am on top of all the maintenance and do everything at or before the specified number of hours.

I use the boat regularly. Normally at least every other weekend, and often more frequently than that. However, being up in NJ in the summer, things really slow down after Labor Day. So there is not much boating going on except for fishing, which I don´t do on my boat. And if it begins to cool down early, no one really wants to go out on the boat because we are all looking forward to the warm winters with the boat down in FL. So potentially there may be 6 or 7 weeks of no boating around that time of the year.

Everyone knows that its bad for a diesel engine to sit. Diesels love to run. So I was told that its a good idea to run the engines at the dock at least once every two weeks and bring them up to temperature. This way you don´t have the same valves open to the salt air for long periods of time (because depending on where the engine stops turning, different valves will be open and closed), the engines get lubricated, etc.

Now, I have also read that idling a diesel engine and running it at no load is not a good thing either. In fact, I read that this will cause more wear on the internal engine parts than running it at load for the same amount of time.

So what should you do during these periods of non-boating activity? Run the engines or not?
 
If sitting for 6 or 7 weeks would hurt them, the diesels in my boat and all of our seasonal construction equipment that sit from the time the asphalt plants shut down in November until April would be junk. You might want to add a little treatment. FWIW, I use Power service Clear Diesel (there are others that are probably just as good) in my boat and all our laid up equipment.
 
It's useless to run them at idle at the dock as they will never get to temp. My friend leaves for Florida in his RV for 4 or 5 months and leaves his 560DB sitting the entire time. He keeps the tanks full and makes sure the proper additives are in the fuel. He has owned the boat for 12 years and everything is perfect on this boat (except the name which needs to change to Plan A when I get it!)
 
In a boat, every brand of engine has limits as far as sitting idle. That is because of ambient temperatures, relative humidity, how tight the engine spaces are, how large the engine spaces intake vent is, etc. About the only way to tell your set up's tolerance for sitting idle is to read your owner's manual relative to extended lay-up or to try letting them sit for the time you have available. It you are stretching the limits for your boat, you will soon tell it in your maintenance and repair cost.

I live part time in Tennessee and part time in Florida; my boat is in the water in NW Fla 100% of the time. I am usually in Florida using the boat every 3-4 weeks for 10-14 days. I have Cat diesels in a Sea Ray and I have found that 5-6 weeks is acceptable when necessary, but beyond that, and I have to deal with absentee owner's issues like getting the marina to clean the strainers, check the shore power service etc., but my engine have shown no negative impact from corrosion or condensation for even the few times we've been caught and couldn't run the engines up to temp and under load for 8-12 weeks.

Here is a side story: I buy and sell light construction equipment for profit and so I can have access to a backhoe, dozer, Bobcat etc when I want it. I recently bought a Case 580K backhoe with a 4B Cummins engine in it that was turned over on its side in a dirt pit. The owner loaned it to his daughter to dig a foundation. Well, a divorce, a bankruptcy and a serious illness diverted everyone's attention and the backhoe laid there on its side for 5 years. I bought it from the bank who held the lien, dug it out of the mud, hosed it off, put a fresh battery in it and it didn't turn over but about 2 times before it fired up. It smoked like the devil on the stale fuel, but I cleaned the windshield off and drove it home. I serviced it, treated the fuel (Power Service Biocide, Diesel Kleen and 9-1-1) and changed all the filters and ran all the old fuel thru it and it never hiccupped or missed a beat and the only repair needed was to replace broken running and work lights damaged when it fell into the pit.......there was no corrosion, no valves stuck, and no effect at all from sitting idle.

Maybe I'm lucky........but I don't get excited about letting diesels sit idle for a few months.
 
Funny, Tom!

Believe it or not, I own 3 Cummins engines and have owned them longer than my Cats.........I love them, but I prefer Caterpillars because of their over design and parts resource.
 
Funny, Tom!

Believe it or not, I own 3 Cummins engines and have owned them longer than my Cats.........I love them, but I prefer Caterpillars because of their over design and parts resource.
 
Those of you who know me frequently abuse me about how few hours I put on the boat annually. And deservedly so. But part of my paltry 40 hours consists of getting the boat off the dock just about every week of the summer. If not a trip to a destination, it will be a short little "cruise of shame" just to ablate some paint and mix up the fuel tanks.

If I had a climate-controlled lower helm and the boat behind my house (I know you have a slightly different situation this season in NJ), I'd take a 1/2 hour cruise rather than run them at the dock, and I'd do it once a week during that doldrum period.
 
I run mine at the dock if I know it won't be moving for awhile, but not really for the corrosion but for everything else. to turn my impellers so they don't set. test the batteries. check for leaks. turn the starters. pump some oil around the engines. check the belts. make sure the alternators are doing their thing etc...
 
Thanks to everyone for their input. I appreciate it.

Now I have a follow up question. So I understand that running the engines at idle under no load is not good. too much wear. But what about running at idle under load. Like when you are in a no wake zone. Lets say you are on the ICW and you hit a long patch of no wake. Is this bad as well? Will this cause excessive wear, or the the fact that the engines are under load make them happier?
 
Under load makes them much happier as well as up to temp. Sitting dock side, out of gear (no load) the engine will not get to full operating temperatures. Even at full throttle (only do this after engine is at operating temp) the turbo won't even kick in or spin up and EGT don't register while at cruise EGT is 875-900 and boost is 15 psi or so. What that means is the governor is not allowing max fuel flow due to no load, supplying little fuel and some is unburned. Running boat excessively at dock just to warm things up has a chance of glazing the pistons and having a carbon build up. At temp and under load, this is very unlikely (read never) going to happen due to heat burning all the fuel making the most power and burning off the carbon that is built up when you have to idle. IF you have to run at extended lengths at idle, follow it up by running the engines at cruise to 'burn off' and warm up the engine. This makes diesel engines happy.

NOTE: unburned above does depend on type of engine (common rail or mechanical governor) but I have mechanical diesels and the that is what this unburned fuel is referring.
 
If your particular engines have a limit on idling, it will be noted in the owners manual and probably have a placard near the helm station advising as such. If it isn't there, a long no-wake zone is just part of boating in So Fla. Extended idling may cause a higher volume of crankcase fumes than your crankcase vent system can handle and you may notice some oil drips from the drain tubes or breather, but that is normal. Some systems, particularly Walker Air Seps do a great job but are sized for air flow at higher than idle rpms and you will get a drop or 2 of oil under the Air Sep after an extended idle period.
 
trit21 said:
... IF you have to run at extended lengths at idle, follow it up by running the engines at cruise to 'burn off' and warm up the engine. This makes diesel engines happy....
Click to expand...

Tom,

This is pretty much in line with what I was advised by my Cummins Tech when I asked the same question about slow cruising at extended periods. He explained that there are tons of different commercial, as well as recreational boats that run at slow speed. So, he said that I can do the same and run all day long at slow RPMs (under 1400RPMs) and all is needed at the end of the cruise is to bump the engines up to normal cruising speed for few minutes to engage the turbos and "clean things up".

I've done tons of slow speed cruising and the temps get to normal operating temps even by going at 1000RPMs for some time. Sue it may take a little longer, but the point is that the engines do reach the normal temps range.

Also, I had no problems getting my temps reach to norm at high idle. This is in fact what I do when changing oils in the fall. I run the engines at around 900-1000RPMs and in 15 min or so I see the temps go to norm. To raise the temp on transmissions, I'll kick them in gear at the dock. I wouldn't advise it if you have low water, but with plenty of clearance it's no harm as long as you don't stir too much silt and don't let it get into the engines. So, my point here's that even at the dock you can get your engines up to normal temps as long as circumstances (plenty of water) allow it.

Everything I've said applies to my blocks, which are smaller than your. So, as Frank pointed out, find what works for your engines. But, I would think that it's not much different, other than it'll take longer to have bigger blocks to warm up.
 
trit21 said:
Under load makes them much happier as well as up to temp. Sitting dock side, out of gear (no load) the engine will not get to full operating temperatures. Even at full throttle (only do this after engine is at operating temp) the turbo won't even kick in or spin up and EGT don't register while at cruise EGT is 875-900 and boost is 15 psi or so. What that means is the governor is not allowing max fuel flow due to no load, supplying little fuel and some is unburned. Running boat excessively at dock just to warm things up has a chance of glazing the pistons and having a carbon build up. At temp and under load, this is very unlikely (read never) going to happen due to heat burning all the fuel making the most power and burning off the carbon that is built up when you have to idle. IF you have to run at extended lengths at idle, follow it up by running the engines at cruise to 'burn off' and warm up the engine. This makes diesel engines happy.

NOTE: unburned above does depend on type of engine (common rail or mechanical governor) but I have mechanical diesels and the that is what this unburned fuel is referring.
Click to expand...

Not looking to hi-jack this thread so a quick yes or no will suffice and I will take my gas burning nose out of your diesel business but does this apply to GAS engines as well? Now back on topic please, and thank you
 
The Volvo D12 is a very reliable engine. The Volvo engine can sit dormant for fairly long periods as long as they are in good service condition and are regularly serviced. Many of our equipment will sit in customs and then at various shipping yards for extended periods then be shipped to the end Customer who may be a seasonal business.

The D12 and all other Volvo engines are used in many different applications from heavy road trucks to dirt equipment or power generation and marine.

Key here in good maintenance.


All that being said when you do start a diesel make sure your warm it up before shutting it down. Also prolonged periods of idle will wash the cylinder walls down and score the pistons.

Letting a diesel set is I OK but when you start it, run it at recommended operating rpm. This keeps the engine oil lubricating the cylinder walls.


Sent from my iPhone using Tapatalk
 
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