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Old 20-12-2020, 11:19   #16
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Re: Auto Diesel engine into boat?

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As I evaluate different repower options, one thought I have is to go to a junk yard and purchase an automobile Diesel engine and place it into my boat. Has anyone done this? What would be the drawbacks?
You might want to subscribe to Boats and Harbors, they have tons of ads for running take outs, rebuilds you name it.

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Old 20-12-2020, 11:39   #17
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Re: Auto Diesel engine into boat?

To the OP - You have probably already seen this ? If not , worth a read: https://wavetrain.net/2011/01/30/bom...soline-engine/ with tips about learning how to live with a petrol powered Atomic 4 engine rather than repowering.

My experience of (paying someone else) to fit a new engine was that it was more involved & more costly than I expected (like always?).

Not at all familiar with electric power on a boat. I assume you mean a battery powered electric motor? How do you charge the batteries? A petrol or diesel generator ?? doesnt that put you back to square one?
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Old 20-12-2020, 11:42   #18
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Re: Auto Diesel engine into boat?

What diesel engined car uses 30 hp or less? I re-engined with a Beta 35, 4 cylinder diesel based on a marinised Kubota fork lift truck engine. Very happy so far...
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Old 20-12-2020, 11:49   #19
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Re: Auto Diesel engine into boat?

The "Marinizing" Process

https://www.glen-l.com/weblettr/webl...inizing-1.html


Short video indicates what is necessary. The peripheral equipment that is necessary to make the conversion. Basically a reconfigured cooling system and exhaust treatment to achieve the requisite air pollution emission standards, e.g., a catalytic converter.
And then there is the mounting and the all important transmission systems.

https://www.google.com/search?q=mari...DcGU-gTntqlo11
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Old 20-12-2020, 13:39   #20
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Re: Auto Diesel engine into boat?

A tractor motor would be a better option. Designed for more torque at lower speeds--but any diesel engine can be converted for marine usage.
You will need, water-cooled exhaust manifold,

Keel cooling piping, or a saltwater cooled heat exchanger.

Oil cooling system, can be in-sump or separate. Can be air or water cooled.

Saltwater pump to pump seawater through heat exchanger, marine water- cooled exhaust manifold and exiting through exhaust elbow.

Exhaust elbow with nozzle baffles to prevent ejected warm sea water getting back to the cylinders when engine is idle..

This water also cools the exhaust stream, making it possible to use special plastic and rubber exhaust components.

Plastic or metal exhaust silencer and water trap.

Plastic riser pipe with siphpn breaker valve to stop seawater surging back to the engine through the silencer, because engine exhaust outlets are at waterline or just above and are frequently submerged when engine is not running.

Of course this can be simplified by using a dry exhaust system--in which you need two concentric pipes and a fan to assist in oil cooling and blowing the hot air out of the outer pipe. Most commercial trawlers in Australia use directly keel cooled diesel engines and dry exhausts. Just be sure not to take the ground on the heel cooling pipes. Think in terms of them being part of the keel itself, or being shielded by lying close to the keel.
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Old 20-12-2020, 13:48   #21
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Re: Auto Diesel engine into boat?

If your boat is a C&C 30 any auto motor will be too big. The smallest diesel I can think of is a 1978 VW diesel at 48 hp. The best part about them is if you overheat them even a tiny bit they blow the head gasket. I used to make money on those engines. My Pearson 30 is running a Yanmar 3GM30F 27 hp and I have way more ponies than I ever need.

I do have a Yanmar 2GM I will sell, pro machine shop valve job recently done on it zero-hours since valve job, sitting on my bench.
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Old 20-12-2020, 15:30   #22
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Re: Auto Diesel engine into boat?

Why would you want to do this? Marine engines are made the way they are for a reason. Auto engines are made the way they are for a reason. They are different reasons because they have different requirements for the very different environments in which they operate.
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Old 20-12-2020, 15:58   #23
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Re: Auto Diesel engine into boat?

Besides all the drama outlined by others, may I just add that for a car/truck engine, sensors such as oil pressure/temperature etc. often use the engine block as the negative terminal where the sensor is attached. That's OK for a truck or car but it isn't a good idea on a boat where the instruments should have a common earth (negative bus bar) to avoid "earth current loops". This means that the sensors are specific for marine use. It's not a great issue but just another reason to consider obtaining a fully marinised diesel engine.
A commercially marinised engine should come with full instrumentation as well.
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Old 20-12-2020, 16:02   #24
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Re: Auto Diesel engine into boat?

Now that the OP has said he has an Atomic 4 and he wants to convert to either diesel or electric the best advice I can give is design the whole power plant backwards. Atomic 4s spin fast and tend to have smaller diameter props. Check your prop clearance for the biggest prop you can install and design from that data point. 15 to 20 HP diesel that spools up over 3000 RPM with a 2:1 reduction might work depending on prop clearances.
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Old 20-12-2020, 16:12   #25
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Re: Auto Diesel engine into boat?

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Originally Posted by billgewater View Post
Besides all the drama outlined by others, may I just add that for a car/truck engine, sensors such as oil pressure/temperature etc. often use the engine block as the negative terminal where the sensor is attached. That's OK for a truck or car but it isn't a good idea on a boat where the instruments should have a common earth (negative bus bar) to avoid "earth current loops". This means that the sensors are specific for marine use. It's not a great issue but just another reason to consider obtaining a fully marinised diesel engine.
A commercially marinised engine should come with full instrumentation as well.
Huh? With the exception of Volvo Penta I can't think of any marine diesel that currently employs an isolated ground system. Perhaps some of the newer common rail engines but I'm not familiar with those.

What you speak of is common practice in aluminum hulled boats but not the common marine diesels found in FRP vessels.
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Old 20-12-2020, 16:40   #26
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Re: Auto Diesel engine into boat?

I'd also recommend Lansing marine. We marinized two VW TDI engines, and removed the turbos to give two 60hp engines at 3600 rpm, or two 40 hp engines at 2600 rpm. Derating the engine, by limiting the RPM is the same way VW does it on their marine diesels.

Cheers and good luck.
Paul.
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Old 22-12-2020, 13:17   #27
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Re: Auto Diesel engine into boat?

Thousands of boats in Asia have wrecked Japanese diesel engines c/w manual gear box and clutch.

My old trawler has a 200hp Merc OM355 bus engine. Marinisation consisted of throwing away the radiator and engine mounts, fitting a Capitol gearbox and running hoses to the keel cooling. That was 20 years ago.

Cheers
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Old 23-12-2020, 04:38   #28
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Re: Auto Diesel engine into boat?

I marinized a Kubota V2203 and fabricated the water cooled manifold from various RHS sections and built the bell housing from alloy plate and flat bar. Initially I set it up for raw water cooling but after fitting keel cooling tubes during a hull refit (steel boat) I switched to fresh water cooling.

I originally planned on using an auto diesel but came into a bit of cash so blew some of it on a new motor. It was an interesting project but a bit time consuming because I fabricated everything myself other than the basic engine and the gear box.

By building the bell housing myself I was able to fit 2 starter motors and implement 2 separate cranking systems. This proved handy at times because the cranking system tends to be one of the less reliable systems on a diesel.

If you do use an auto engine you need one with cast steel block and heads if you want to raw water cool it.
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Old 23-12-2020, 05:06   #29
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Re: Auto Diesel engine into boat?

Atomic 4 were reliable but not very powerful.

If you are contemplating electric it could get you in & out of a marina , but not far after that.

If cost is a factor you might consider a 12-14 hp gas replacement engine from an equipment source.These are air cooled (leave the hatch open) and have a 4-1 or 6-1 built in reduction so will spin the A-4 prop with ease.

They have no clutch or reverse gear , no big deal as at idle the prop turns so slow little thrust is produced.

Made to operate at near full power for long work days they are very reliable.

Brand new , And cheap! Compared to "marine" anything.
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Old 23-12-2020, 05:44   #30
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Re: Auto Diesel engine into boat?

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Originally Posted by GoneDiving View Post
Thousands of boats in Asia have wrecked Japanese diesel engines c/w manual gear box and clutch.

My old trawler has a 200hp Merc OM355 bus engine. Marinisation consisted of throwing away the radiator and engine mounts, fitting a Capitol gearbox and running hoses to the keel cooling. That was 20 years ago.

Cheers
lol, this gave me the mental image of a Honda Civic manual shift knob poking out next to the helm.
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