marine diesels

[Anonymous No.2019117]

I am getting ready to buy a boat and will need to learn about maintaining a diesel and how to give a diesel the once over before buying. I have little experience with engine work and would call myself completely ignorant, I can do simple things like change oil or a belt and the like but that is about it. Any good resources? Google just keeps giving me wikihow tier results as any search I do shows my ignorance and google rightfully identifies me as clueless. Any general words of wisdom?

Also, pic related is the engine of a boat I am thinking of going to take a look at, it looks well maintained to my untrained eye, especially for a 40 year old engine. Does anything jump out from a visual inspection of the pic? All I can really tell is the mounts look good and show no signs of the engine moving, that hose in the bottom suggests something has leaked? What would turn the hose that color? Any idea what that hose would be?

Trying to decide if this boat is worth the trip to give it a look over, it is a decent ways away and will eat up an entire day, possibly two if I want to avoid spending most of a day on the road.

[Anonymous No.2019125]

>>2019117
Dont mean shit without knowing hours and compression.

[Anonymous No.2019126]

>>2019117
don't buy a boat. it's just a money pit.

rent a boat for the handful of times your wife lets you go out "on a fishing weekend with the boys".

[Anonymous No.2019127]

I would look for a car engine that is converted for use in a boat.

Its actually only a different radiator, that uses the surrounding water instead of air to cool the engine. A water to water heat exchanger.

Dont know how much space you have, but I would consider a mercedes diesel engine.
Something without a turbo from a w123.
Zero electronics, runs for ever.
Only downsid is the iron block.

[Anonymous No.2019130]

>>2019117
Caveat: i don't know shit about MARINE diesel engines, but
Yanmar is a decent brand, you see the model on the nameplate, find a service manual for it online, check for a way to measure the compression, borrow the tool and make a measurement, if it's in the range given in the manual then the most important thing is good. The engine looks like it was cleaned to take the pic, there are parts which show it was right up foul before, that's not a bad sign actually, the seller probably just couldn't give a fuck to clean the hose fully. Some parts look way to new too, so there is a chance it was refurbished or at least was in good enough care. There are countless books
<<< like that, which deal with amateur engine maintenance, look for some.

[Anonymous No.2019148]

>>2019125
1205 hours, no idea on compression. Sellers do not test that. Compression would tell how good the seals and the like are? High compression means no leaks?

>>2019126
It is going to be my home, renting a boat would be obscenely expensive for that and would defeat the purpose.

>>2019127
Why would I do that? If the boat comes with a good engine I am not going to replace it. Also, few car engines will fit in the engine compartment of a 30-40 foot sailboat.

>>2019130
Thanks for the info anon.

[Anonymous No.2019152]

>>2019148
>Compression would tell how good the seals and the like are? High compression means no leaks?
Diesel engines require high compression to work, the air heats up like a retard when compressed and diesel fuel is injected in, things go boom. If the compression is low, that means the engine is well worn, possibly will require expensive rebuild and may or may not be worth the trouble. As for leaks, compression has nothing to do with that, but cracks (very unlikely) and failing connections/threads (not that likely either) all leaks you may have are a matter of changing the seals/hoses, which is not expensive nor complicated.

[Anonymous No.2019154]

>>2019152
s/but/but except

[Anonymous No.2019157]

>>2019152
Ahh, so compression is a function of the pistons fit in the cylinder, low compression means the pressure is escaping between the piston and the cylinder wall?

I would assume an engine with 1200 hours would be unlikely to have issues with compression if it was properly maintained? So in this case compression is a good indicator of how well the previous owners have maintained the engine?

[Anonymous No.2019167]

>>2019157
>low compression means the pressure is escaping between the piston and the cylinder wall?
Yes, or the valves are damaged/worn/non-adjusted or the head gasket is damaged.
>1200 hours would be unlikely to have issues with compression if it was properly maintained?
Unlikely, IF it was maintained properly.

[Anonymous No.2019193]

>>2019167
Ok, thanks. Since that very new looking lower left pulley/bracket are for the water pump it suggests the pump was replaced, which seems to be about 4000 hours shy of the average water pump life span for these engines. A compression test is very much in order if I check out this boat.

[Anonymous No.2019250]

>>2019117
I have a similar year 3GM. These engines are tanks. With saildrive mine is over 700lb's. The big question I have for you is where that boat lived/s? Salt or fresh water? I hope fresh because it doesn't have a heat exchanger and that would probably be a deal breaker for me. The angle iron on the engine bed isn't original. It being unpainted and not rusted means it's relatively new. Probably is an okay repair if painted.

You can learn a lot about a diesel by starting it up. How easy it starts and how quickly it evens out tells you about compression. How low it idles and how quickly is reacts to throttle tells you about the injectors. Getting a good heat soak in her will show any exhaust issues or oil leaks.

If she's on the hard check the cutless bearing and replace it if it's wore at all. Same with the packing box. Best to do it before splash.

If the boat's been out of action for a while don't be surprised if she develops an oil leak after a few heat cycles. Orings that have been dry will make themselves known. There should be a fiberglass engine pan under the motor to catch fluid leaks. Looks like that boat is missing it's pan. I'd put something under it to keep oil out of the bilge.

>>2019127
Bro, you don't put gas engines in boats. That's how splosions happen.

[Anonymous No.2019274]

>>2019250
It most likely has seen little if any salt water, made on Lake Ontario, currently on Lake Superior. What does the heat exchanger actually do here? I will be heading out to salt water, is a heat exchanger a difficult thing to add? There are not many salt water ready boats in these parts, so I expect to spend some time and money on this.

Bearing and stuffing box are already on the list, they are things I understand.

I do not know anything about the boats history yet, I think it has been up for sale for at least a year though, so has been on the hard for awhile. Pretty much no boat sales happened last year thanks to corona, no one sold, no one bought, market was dead.

[Anonymous No.2019294]

>>2019274
Right now that engine is raw water cooled. It sucks in whatever you're sailing in and pumps it thought the engine. That's okay for fresh water but in salt you'd be pumping salt water though the block rusting it from the inside out. Alternatively you run a closed loop system of antifreeze thought the block and into a heat exchanger which also has raw water pumped though it absorbing the heat. Keeps salt out of the engine. An added bonus is if your water heater has the ports you can circulate the engine coolant though the water heater and get hot water on the hook.

[Anonymous No.2019340]

>>2019294
Ahh, i remember reading about this. The cost of adding a heat exchanger is probably not worth it, costs almost $1500 for the yanmar exchanger, could be cobbled together for less but probably not worth it for a 40 year old engine which likely has seen little to no salt water. Especially considering that most seem to get at least 20 years of salt water through these things before it is an issue. If i go with this boat i think i would call it good, dont plan on doing much motoring anyways, it is not strong enough for bad weather and i am perfectly happy to sit out calm weather, so it will just be used for tight spaces were sails are impractical. Thanks.

[Anonymous No.2019373]

>>2019340
You do you but just because you're not running the engine doesn't stop the salt from eating it. That water sits in there running or not. You don't need yanmar parts for this. An aftermarket jasco pump with any used exchanger for something in the 20 horse range will work. It's nice to be able to charge the batteries on cloudy or get somewhere on calm seas.

If you are going to run raw water keep a lot of engine zinc's on hand and change them often. That girl probably uses pencil anodes that won't last 6 months in salt.

Happy sailing.

[Anonymous No.2019400]

>>2019117
That's not a motor m8

[Anonymous No.2019559]

I'm a Merchant Marine licensed engineering officer. I work with high speed Diesels, CAT mostly. Usually much larger than this Yanmar so i have no specific experience with it.
As some have said, see if you can get a compression test on it. owner may not want to do this as it involves removing the injectors, and bleeding air out of the injectors can be a bitch, but its the best way to gauge the engine's conditon.
1200 hours is nothing. We generally change oil every 1000 hours on our 3516 CAT main engines. They get total rebuilds at 20,000 hours.
>>2019130
This book is a good primer for someone who knows nothing. Its on my shelf somewhere, i bought it just to see what it was about because its so often recommended. Its written for the small boat owner like you are going to be.

[Anonymous No.2019642]

>>2019400
>filename

You clearly don't understand that concept.

[Anonymous No.2019809]

im this guy >>2019125
go get the specs for that engine before the test. learn the maint schedule, and determine if it was followed correctly. if none of this makes any sense, get a pro to come look, and learn from it. 1 jug at 350psi or less - that engine will need a wrench soon. but dont take the word of internet shitheads, get the fucking book, lrn2readit. thats how you cya and make informed decisions.

[Anonymous No.2019840]

i agree with the anon that mentioned you can learn a lot about a diesel by the way it starts.


Carry on.

[Anonymous No.2019983]

>>2019809
>350psi

Huh? This is a naturally aspirated 40 yo boat engine. It's ~22 hp with a compression ratio of 20:1. They aren't physically capable of 350 psi. A compression test is a waste of time that could end with a broken injector (even if you have the correct pull tool).

We're talking a 2 cylinder diesel. Spin it over with the starter and you'll be able to hear if one cylinder is low. You can even use the decompression levers to figure out which one. OTOH those injectors are getting rare. $250 a pop depending on revision.

[Anonymous No.2020016]

>>2019983
youre right 350 is more 22/1 just doing quick math.

for that size i wouldnt be 350 more like 300. The ignition pressure of diesel is 234. its why i told op to get the specs which you graciously posted.

>40yrs old
>1205 hrs
>shiny
sounds fishy af.

[Anonymous No.2020029]

>>2019250
>Bro, you don't put gas engines in boats. That's how splosions happen.

Bro, the om617 is a diesel engine.

>Why would I do that? If the boat comes with a good engine I am not going to
>replace it. Also, few car engines will fit in the engine compartment of a 30-40
>foot sailboat.

parts availability?
also pic related: the engine istn really that big.

many old boats have either a swapped mercedes or volvo engine
They are overengineered and made to run all day.
These engines are even used as backup generators in hospitals.

[Anonymous No.2020034]

>>2020029
>These engines are even used as backup generators in hospitals.
not in the northern hemisphere

[Anonymous No.2020038]

>>2020029
while doing some research I found this behemoth:
the OM 424 LA
>v12
>diesel
>twin turbo
>displacement: 20.93L (127.7 cubic inches)
>615hp

this is a legit tank engine

[Anonymous No.2020095]

>>2020029
I'm familiar with sailboats and also the venerable OM617 engine. (I've owned two 300Ds). Unfortunately, you would be hard pressed to fit that in an sailboats engine compartment. You also would be over powered. Most engines for sailboats that size range between 20 and 40 horsepower.

[Anonymous No.2020106]

>>2019559
Thanks, added the book to my next order.

>>2019840
Care to elaborate on that?

>>2019983
13hp, this is the plain jane old fashioned 2GM, think the highest HP of the 2GM series was 18HP?

I am guessing if a cylinder has low compression it will sound quieter or less distinct from the other cylinder since not all of the fuel will explode when injected? So smaller boom? And there would be a hiccup in the rhythm?

>>2020016
>sounds fishy af.
It is a sail boat, engine is secondary propulsion. Many people only use their engine in the marina and this being the great lakes boats are only in the water for half the year and many will do or have the marina do general maintenance during that long off season. This is on the low side but not insanely low by any means. This boat looks like it was very well maintained over all, nothing on it looks anywhere near 40 years old.

>>2020029
Still an idiotic move, just because some do it does not mean anything. If this engine is in good working order it is hard to beat for my needs, almost every marina will either have spare parts or a few old junked engines to pull parts from.

[Anonymous No.2020128]

>>2020106
knowing full well what lake superior and Ontario are like i typically like the boat engine to work in a storm. youre probably right op but paranoia pays off in the great lakes. too many time ive been caught up in those waters.

[Anonymous No.2020145]

>>2020128
I will be long gone from the great lakes by the time the fall storms set in and there is no reason for me to be out in such weather, forecasts are good enough these days that I can wait out such weather in protected waters. I would much rather be comfortable below decks reading or something than fighting the weather and if I have to fight the weather, I would rather do it with the sails, time goes faster when you have something more to do then sit wet and miserable at the helm. Also, even if the engine is not strong enough on its own to fight a storm, it combined with a little bit of sail will do the job.

[Anonymous No.2020505]

>>2020106
Oh right, you got a GM. AFAIK they're stock 16 hp but different variations are rack limited. I looked up specs for an older QM which were 18 hp. You said a 40 yo boat right? It must have been repowered to have a GM in it.

When you're cranking it over if one cylinder has low compression the speed that the starter is spinning over the engine will vary and sound something like this: https://youtu.be/zdWG9n3kcbk?t=32

This is how a low compression diesel starts: https://youtu.be/ptrfWzkaOI8?t=283

This is how it should start: https://youtu.be/fw0LWNvVyKs?t=94

[Anonymous No.2020596]

>>2020505
38 years old, the 2GM was fancy new tech still but they were out. 13hp is what is on the plate, marina lists it as 18hp, so who knows.

What does rack limited mean? I am getting no results from google on that one. Maybe you might be confusing the specs of the 2GM and 2GM20, the 20 was bored out to get a few more hp.

Thanks for the links.

[Anonymous No.2021450]

>>2020596
>What does rack limited mean?

not that anon. the rack is the throttle. try googling: diesel fuel rack. i dunno much about boats but 13 hp seems extremely underpowered for a big boat. rubber boats have more on them then that.

[Anonymous No.2021856]

>>2019642
Obviously he doesn't. If we wanna talk no efficiency, talk about something that isn't slow speed.

[Anonymous No.2021864]

>>2019126
fuck off but you're right

[Anonymous No.2021876]

>>2019117
Alright OP, I've lived on sailboats for years and I have experience working with these pieces of shit, take everyones advice with a grain of salt.. especially when they say they dont know anything about MARINE diesels. there's a lot of shit to check that i could never communicate, my first diesel had worn down cams on the fuel pump and it was bought on the hard so couldnt test. if at all possible make damn sure you try to start the engine when you look at the boat. MAKE SURE the engine is cold BEFORE the seller starts her up. check for surface rust on the engine, not a big deal but tells you something about maintenance history. Check hoses. are they rotted? rusted? marine spec trident wet exhaust hose has a wire reinforcement, very expensive, 7 dollars a foot for one inch hose, 3 inch 20 dollar foot. check the oil filter, is there a date on it? how does the engine sound when it runs? hard to tell by ear at first cause marine diesel makes weird noise (all systems are MECHANICAL) no computers, wait till it warmed up for accurate sound. make the seller run her up to full neutral rpm, diesels love being run hard. Wait for her to go up to temp, if the temp gauge doesnt work, big issue. check the manual beforehand for operating temp range. check the water exhaust. should be warm, not scalding. what color smoke is coming out if any (research this on forums). check wet exhaust output, low idle should be a burst of water every couple sec, high rpm should be almost constant gush. make the seller put her into gear both fwd and reverse, look at the shaft spinning. there will be a stuffing box (shaft gasket) just inboard of the cutlass bearing (shaft thru hull penetration bearing) when spinning should have a slow drip of water. check condition of fluids (maintenance history

might help might not, too many possible issues to list

[Anonymous No.2021878]

>>2019157
1200 hour engine could be clonked out or could run another million. all depends

[Anonymous No.2021884]

>>2021876
ask owner about zincs too

[Anonymous No.2022102]

>>2021450
Ahh, so the rack is just offset, has a stop, or too short top open the throttle all the way. Thanks. It is a sailboat, if I need more power I can add sail, 13hp is enough to get in and out slips and move about a packed marina and that is it's main use here.

>>2021876
>take everyones advice with a grain of salt
life has taught me that the advice of those who preface their words of wisdom with this phrase should be taken with the biggest grain.

[Anonymous No.2022104]

>>2019117
>dat instant gasket on the fuel pump
may be a bad sign but without seeing it in person nobody will have a clue

[Anonymous No.2022144]

90 percent of the time problems with diesels is with the fuel supply. Learn how to bleed the lines inside and out

[Anonymous No.2022147]

>>2022104
Is that the squeezed out gunk right above the name plate? And that would be the injection pump and not the lift pump?

What can this suggest beyond a sloppy install? Any other problems this should suggest I watch out for?

>>2022144
Bleeding to remove air from the lines? Or are you implying more? I have read some on this but everything just mentions bleeding air out at the filter, does this remove it from the entire system or is there more?

[Anonymous No.2022164]

>>2022147
>Is that the squeezed out gunk right above the name plate
yeah
I'm just guessing here since I'm not familiar with this particular engine but judging by the lines coming from it yes that's a high pressure fuel pump for the injectors
Alone it doesn't mean anything more than what you said possibly shoddy workmanship but in my experience shoddy workmanship isn't restricted to one example IE there could be more work done to it with the same level of care
Again, I don't know this engine and perhaps in the workshop manual it states to use some form of instant gasket on this part. You need to see it and ask these questions in person

observe it running, listen for knocking or excess tapping
check oil for water ingress
other than that you could do with somebody familiar with marine diesels to help you

Ask on /o/ also since there's a lot of very engine-savvy lads over there, make a new thread or post in QTDDTOT

[Anonymous No.2022174]

>>2022102
Rack is not "the throttle" rack is the cam driven mechanical injector actuation assembly.
Calling the rack the throttle is like calling the butterfly valve on a carb the throttle.

Bleeding the air is more than just the filter. You bleed the air after a filter change in order to avoid getting air lock in the pump or lines. Mechanical diesels are very sensitive to this. Basically if you get air inside the injector pump or lines it won't ever push fuel through.
There will be places such as the injectors or pump output lines that you need to crack open in sequence along with cranking the engine in order to bleed the air out.

[Anonymous No.2022187]

>>2022164
Thanks. I will start a thread on /o/ this weekend.

The injector pump was actually a part that jumped out too me because the nuts and a bolt where replaced with something that looks to easily rust and there are no signs of any anti-seize or grease on the visible threads. This is one part I expected to pull before heading out to salt water just for ease of mind, assuming it is not something too involved. I did not even notice the gasket until you mentioned it.

>>2022174
I was not calling it the throttle, at least I don't think I was, but I really haven't a clue. Thanks for the clarifications.

[Anonymous No.2022207]

>>2022187
indeed it seems there should be 2 gaskets. Somebody has definitely had it all off and resprayed the whole area silver after putting it back together. Requires closer inspection I'd say
I'm sure this will be a handy link for you if you end up purchasing it

http://www.marinedieseldirect.com/catalogs/catalog.php?owner=mdd&model=2gm&manufacturer=yanmar&catalog=y00r0902

[Anonymous No.2022242]

>>2022187
also yes regarding the fixings one would expect them to be stainless, or non-ferrous plated if they require a higher tensile strength than stainless A4 can provide

[Anonymous No.2022502]

>>2019117
Just remember OP, boat stands for Break Out Another Thousand. Hope you got the money

[Anonymous No.2022504]

>>2022242
The original hardware isn't stainless. The injectors run at ~2200 psi and the lines are painted steel. It doesn't matter really. OP's engine is raw water cooled. It'll have salt running though the water jacket.

[Anonymous No.2022801]

>>2022102
someone who takes a strangers knowledge without question has none of their own

[Anonymous No.2022857]

>>2019127

I've also seen people use the BMW straight 6s, M57s and earlier. It's a shame what they did to modern diesel engines, but I suppose it was necessary....

[Anonymous No.2022929]

>>2022504
Are bare mild steel fasteners common on marine engines?

[Anonymous No.2023100]

>>2022502
Do you really find this to be clever or funny or even wise? You are like the fourth person it to express this sentiment without bothering to read the thread and find out my situation. There is absolutely nothing about owning a boat that makes it expensive, there are just a whole lot of stupid people that neglect their boats all year and once they finally go down to the marina discover that simple to fix problem has become rather expensive. Maintain your boat, park it a mooring, it will cost you a few hundred a year at most.

>>2022929
Most of those are Grade 7, but it depends on the use. An engine like this one will live a dryer life with less stress than most car engines a marine diesel in a boat like this will never see a pothole or deal with salty tire spray, and will only run a tiny tiny fraction of the miles traveled by the boat.

[Anonymous No.2023179]

>>2019117
I had this exact motor in my boat. It just fucking worked, never had any problems with it and it had a lot of hours in it. When I took it over it was badly servived by previous owners but still worked like a charm. Just do yearly services like fuel filter, change of oil etc and you're fine!

[Anonymous No.2023202]

>>2023100
Your retarded, I grew up working with my dad in his marine repair business. You said you know nothing about the diesel engines and you're saying they're not expensive to repair and maintain? OK. Hope it sinks with you in it

[Anonymous No.2023217]

>>2023179
Most everyone seems to agree that these engines are very difficult to kill.

>>2023202
Just because I know nothing beyond simple maintenance like oil changes does not mean I have no knowledge or experience regarding the cost of maintaining and owning a boat. Believe it or not there are these people called mechanics, you provide them with money/goods/services and they do the work for you, I would expect you to know this given your unverifiable background.

[Anonymous No.2023231]

>>2023100
>Grade 7
>shitload of rust
>is obviously just mild steel
Yeah I'm thinking the fasteners in question aren't original

[Anonymous No.2023232]

>>2023231
You can see the 7 on most of the bolts. It is already established that the rusted ones are not original.

[Anonymous No.2023261]

>>2023217
Do yourself a favor and don't buy the boat, wrenchlet

[Anonymous No.2023265]

>>2023232
bro I'm not sure if you're the same anon these last few posts but if so was this a subtle troll?