NOT running diesel under load anxiety

[sinnerman]

You might think of performing some maintenance on the diesel if you just bought the boat from someone else. You often cannot depend that the person before you did the proper maintenance.

- Check all the hoses for cracks & damaged /rusting hose clamps.
- Replace the engine coolant
- check the condition of the seals on the coolant reservoir cap
- Replace the fuel filters
- Replace the engine oil & filter
- Open up the water pump">raw water pump and check/change the impeller
- Clean the heat exchanger.
- Replace the zinc(s)
- Have the fuel tank cleaned ("polished" ) to remove water and algae
- Make sure the cap on the fuel fill inlet on-deck has a good o-ring on it (water can enter the fuel tank..)
- Check the belt condition / alignment. (A lot of black "belt dust" is a giveaway)
- Replace the transmission fluid
- Check the battery & battery terminal condition
- Check the condition of the battery cables at the starter and ..the GROUND cable on the engine.

Often ignored maintenance items:
- Valve adjustment (valve "lash")-Needs adjustment every xxx hours
- Injectors - They periodically need to be removed, cleaned and tested
- Exhaust mixing elbow internal condition (it rusts out)

Cheers


DD[/QUOTE]

[PineyWoodsPete]

Originally Posted by DoubleD

Chris Mac, are your 3gm30f's original? Mine is 1991 so possibly similar in age. I've yet to dismantle the cooling system, but plan to this winter. Water flow overboard appears sufficient, but I'd like to get a look inside just to be sure there aren't any obstructions brewing. I haven't run it up to full throttle yet and couldn't during sea trials as there were issues with the shaft coupling, which the seller fixed prior to sale. When starting, do you apply full throttle? I'll continue to use as needed.

DD

NO! Just start it with throttle at idle setting. With this, diesels will generally run for a bit at 2-300 RPM above idle, then fall to normal idle speed with oil well circulated. Now you can increase RPM in N if you wish to 1500 or so to warm up a bit, or leave your slip and gradually increase throttle a bit until operating temp reached - generally ~170F or 75C, when you can go to full throttle gradually to see if the seller's fix worked or other issues such as smoking, overheating or not getting near the max rated RPM, which you can find in the manual.

I would have checked all this out before closing, though!

[Celestialsailor]

Originally Posted by ItDepends

What IS bad for an engine is to run short and cold cycles. Start, run 10 minutes, then shut down. No matter what the load imposed, if the engine doesn't come up to temperature, all kinds of problems can manifest themselves over time.

I can attest to this. Bought a Hallberg Rassy 35 that was cheap due to an engine that was considered seized. When I looked at it, I took a large crescent wrench and noticed it would not turn in the direction it was suppose to but could rotate backwards about 355 degrees. I bought the boat and did a total rebuild on it but the actual problem was the piston was so carboned up that the piston was hitting the carbon. There is less that .020" from the piston to the head for compression purposes anyways.

What had happened was after the former owner passed away, well intentioned (or not) friends of the former owner started the engine for 5 minutes once a month for a year or so, then finally stopped. This carboned up the head. It sat for another year in Berkeley Ca. where it is very moist in the air. The carbon swelled up and then the family listed it and the broker found the engine could not turn over..."Yup...she'd seized!"
The whole idea with running a diesel is to let it warm up to a temperature that clears the carbon out. Anmd of course this is aided by putting a load on it. Have you ever noticed a diesel big rig when they accelerate onto a highway, they belch black smoke?...carbon.

[danstanford]

Originally Posted by Pete the Cat

The only issue about running in gear at the dock is not just your dock lines but the cleats. Boats have been holed and boaters have been killed by cleats being pulled at catastrophically high impact speeds from the dock. It doesn't happen often, but it has happened. This is very likely why the marinas prohibit the practice.

I think the suggestion was made assuming you would use a limited throttle.

[GrowleyMonster]

Occasionally running your diesel for a few minutes with no load isn't going to significantly impact engine wear, perfformance, or lifespan. Every 2 to 4 weeks it is good just to crank it up and blow out the raw water system, wet elbow, fuel system, etc and maybe heat up the alternator and the starter motor a bit. Where you begin to run into problems is sustained and frequent (as in severral times a week, for a couple of hours or more) operation at very low load, such as charging batteries with a regular OEM alternator. Or maybe idling in gear for hours on end.

This was more an issue when diesel fuel had higher sulfur content and could form sulfuric acid when not completely burnt. Now, mostly it is all about carbon buildup and just cranking the engine every few weeks and running no load for a minute or two does more good than harm. Possibly, excepting turbocharged diesels. I can't comment on them with authority in that regard.

Of course you can also just take the boat out and motor around a bit, at cruising speed, and go ahead and burn up a gallon or two of the old fuel you have been hoarding in the tank for who knows how long.

[bcboomer]

Who are you going to listen to?
Boat owners with a sample size of 1 or 2 or the manufacturers with a sample size of millions over decades?

All diesel manufacturers that I'm aware of state that you should not start the engine without warming it up completely. When they talk about warming it completely they are talking about oil temperature, not coolant temperature.
It takes more than 10 minutes at low load to warm up the oil.

Cummins, Caterpillar and Peugeot all recommend only allowing 2 or 3 minutes at idle then a moderate load until fully warmed up. I suspect all other diesel manufacturers say the same.

They know what they are talking about.

[Cheechako]

Originally Posted by DoubleD

I have anxiety of starting my diesel, without putting it under load. I recently acquired my Caliber 33 and hope to keep its Yanmar 3GM30F diesel running strong for many years. Having read about the ramifications of running a diesel without any load, I’m reluctant to start it up without taking it out of its slip to motor around to put a load on it. What is worse, not running the diesel at all, or running it without some sort of load? I know one reason to run it under load is to get it up to temperature so that carbon deposits and raw water condensation don’t muck up the cooling system. I currently don’t need to run it to charge the batteries as I’m in a marina on shore power. The boat does have an engine driven refrigeration compressor, is that enough load? Although I’m down on the boat every few days, I can’t always take it out. I suspect the answer is somewhere in the middle. Start it every few days but run it under load every few weeks? Thoughts?


DD

My boats have all been engine charging... mostly (no large solar panels or wind gens). I've never experienced issues with running just that small load and you can hear the diesel work when the alternator kicks in. Especially the 3GM30 which is what... about an 18 hp engine at less than the 'airplane speed' Yanmar recommends? At say 1200-1400 rpm you are probably putting out 10 HP max? (I dont have the curve handy)
-You can run at the dock with it in gear, and may need to in order to get it to warm up properly anyway. That's what I've done a lot.
-Consider not having it on the shore power charging, then when you start the engine, your alternator will be loading up the engine using maybe 4 HP of the 10 HP or so.

[chris mac]

Originally Posted by sailmontana

Q: what does the "partial rebuild" entail?

I have two of what I have also been told is the best yanmar, the 4JH4E w around 7000 hours and want to see 10K, what are the greatest hits of service for these older work horses?

J-

By partial rebuild, I used a more politically correct term than I was given.[emoji41] My mechanic, who has been working on diesel engines longer than I've been alive, called it a mexican rebuild.
He mounted them on his work bench and tore them down. Replacing or repairing what was needed. Also cleaning, repainting, ect. Since parts for the vdrive are hard to source, he also fabricated some parts
We only had 1 working hour meter prior, and it was just shy of 9000. He felt we shouldn't have any issues for another decade of use.
The pic is after rebuild, before install.

[Cheechako]

Originally Posted by chris mac

By partial rebuild, I used a more politically correct term than I was given.[emoji41] My mechanic, who has been working on diesel engines longer than I've been alive, called it a mexican rebuild.
He mounted them on his work bench and tore them down. Replacing or repairing what was needed. Also cleaning, repainting, ect. Since parts for the vdrive are hard to source, he also fabricated some parts
We only had 1 working hour meter prior, and it was just shy of 9000. He felt we shouldn't have any issues for another decade of use.
The pic is after rebuild, before install.Attachment 266779

In auto work we would call that an "Overhaul". As opposed to a rebuild which would include most everything rebuilt.
The Overhaul was rings, bearings, valve grind etc. and anything it obviously needed. But worn camshaft or bearings, new tappets, distributer? etc... unlikely.

In those days car engines didn't last near as long as they do now, so many of those perpheral things weren't that worn at 80000 miles when the valves or rings might be. Now a car engine goes 200k miles +.

[sailmontana]

thanks for all that, love this place!!
J-

[Baby tug]

This is a pet peeve of mine it does not hurt your engine at all running it right above idle all day long every day year after year after year , not true that it hurts your engine and carbons it up , I’ve been around diesel engines my entire life mini small excavators that use the same engines that you find in your sailboat run just above idle all day long every day and will go thousands of hours , The last one I rented had 36,000 hours on it , you were given instructions when you rented it to run Just above idle never give it any more power than absolutely needed , written right on the contract that you signed , it doesn’t seem to hurt that much either to run them at full throttle continuously I recently read an article about a generator that was used to power lights and ventilation in a long tunnel that ran 24 seven 365 days a year it was set up so you could change your oil while running and fuel filters of course they retired the engine when I was in excess of 200,000 hours send it back to the manufacturer For an overhaul the manufacturer sent them a brand new motor , At no cost and they wanted to keep this motor for advertising , When they tore it down they found the internals to be all within specs , it didn’t need a rebuild , What kills your engine in your sailboat internal rusting , moisture in the cylinders rusting the cylinder walls etc. etc. and starting them puts most of the Where on the engine , No oil circulating !!!!! , There’s a commercial boat kitty corner from my boat that has some kind of caterpillar in it , it has 80,000 hours before the top was gone through if you want to know about diesel engines and boats talk to the commercial fisherman , these websites are full of misinformation, I’m sure many of you Well argue with my points it will fall on deaf ears ,If I were to spec a new engine for my boat I would spec one that would give me the power needed between 1400 and 1600 RPMs it would be propped that way as well, Just as a sidenote Boat Kitty Korner form me ran between 1400 and 1600 RPMs its entire life

[Celestialsailor]

Originally Posted by GrowleyMonster

Occasionally running your diesel for a few minutes with no load isn't going to significantly impact engine wear, perfformance, or lifespan.

Originally Posted by Baby tug

This is a pet peeve of mine it does not hurt your engine at all running it right above idle all day long every day year after year after year , not true that it hurts your engine and carbons it up ,

Either you guy's missed my (Post #33) or you guys just don't believe or like me anymore...which would really hurt my feelings!

[Baby tug]

[QUOTE=Celestialsailor;3701939]Either you guy's missed my (Post #33) or you guys just don't believe or like me anymore...which would really hurt my feelings![/QUOT


Would you like to make a wager , I will , you got an extra 10 grand laying around , I don’t know what caused The problem with the boat you bought, I would look at the wet exhaust that causes problems that anything else

[GrowleyMonster]

Originally Posted by Celestialsailor

Either you guy's missed my (Post #33) or you guys just don't believe or like me anymore...which would really hurt my feelings!

Now don't sulk... we still like you just fine!

[Celestialsailor]

Originally Posted by GrowleyMonster

Now don't sulk... we still like you just fine!

Ah shucks!