For marine diesel setups in general, the raw water pump is an impeller pump with a neoprene impeller. This allows it to self prime from the sea water. It circulates the sea water around the heat exchanger which contains the internal coolant passages. Usually, the pump that distributes coolant in the closed coolant system is a traditional style water pump called the circulation pump, often belt driven. After the sea water has passed through the heat exchanger, it is expelled off of the boat, sometimes cooling the exhaust as well.

First diesel I ever worked on as a teenager in the early 70’s. Had a blown head gasket and broken head bolts. Fixed all that, started it, and it promptly ran away! Stuck my thumb into the little hole in the air box and stopped it. Turned out the throttle shaft on the fuel pump was broken. The governor moved, the shaft turned, but did not control the fuel. Had the fuel pump, rebuilt and everything ran alright. Been in the marine business ever since.

Was a mechanic by trade retried now never got involve with gen sets watching you work on them glad now I stayed clear as they are more complicated than I thought I love watching you work on them as you know your stuff 😁👍

Bonus points for installing an air filter. 😉👍 I always run air filters, but they probably didn't consider a marine environment as very dusty.

That was absolutely fantastic!!!!! Outstanding Job Mike!

The raw water will have a rubber impeller. It is water cooled and lubricated. It is not meant to handle 180 degrees. Typically they are made by Jabsco. The other circulating pump will be a centrifugal type with a aluminum or composite impeller which can handle 260 degrees. You are spot on with everything thus far. The exhaust riser looks like it froze.... but in a boat everything will rust. There's always a small amount of water in the bilge and the engine heat causes humidity to oxidize everything that is susceptible. Great content Mike! Edit: the antifreeze coolant runs through the heat exchanger, block, head, and the exhaust manifold. The only thing that is not coolant filled is the exhaust riser or elbow. That's were the spent raw water exits and is introduced to the exhaust hose to cool the gas for through-hull plumbing. The riser is usually replaced every 4 to 6 years for obvious reasons... You can put a radiator on it and exclude water exiting the exhaust. It will be a "dry" exhaust instead of "wet" exhaust at that point. You are not going to have any problems with what you are going to do! Very excited to see more!

I really enjoyed this video, as I am a retired Marine Mechanic and have worked on a few of those. Those came in gas also, for smaller gas powered yachts. I found, if there was a generator hour meter, they often were very close to the main engine hours, or they had very low hours....

Nice little unit Mike! You know, seeing as it's water cooled, why not run a couple tubes back from your service truck cooling system to cool it? Not only will it cool it, but it would also keep it warm in the winter with the truck coolant circulation, for easier cold starts. Also it would reduce the amount of space it takes up, not having to deal with a separate radiator. As long as it's the same height or lower than the existing cooling system, it should be a cinch to bleed the air out.😉

I know very little about diesel engines, but now I can learn. Great videos, thanx.

NICE VIDEO! I inherited a 15RDJC from my father-in-law. Mine has the YD generator, runs and generates nicely. Mine has some sketchy wiring, but works fine. You're right about the Magneciters: people either love them or they hate them! Interesting fact on the RDJC's - the water pumps were hard to find. But I figured out that a 1942 to 1953 Studebaker Champion water pump works with a little modification. Turns out at one time, Onan was owned by Studebaker!

Not often I catch a video so early KZfaq hasn't finished processing. LOL.

Nice to hear it run again. Nothing like bringing an engine back to life. Good job Mike.

Great video I work on Marine engines here in the UK . Going by the elbow water connection on top of the exhaust pipe , it would have probably had a water cooled rubber exhaust pipe . It is a direct route for cooling water out of the exhaust to enter the engine through the exhaust port and valves, especially if the sea cocks are left on and the boat has being rolling around at its moorings.

Great job getting that started Mike!

Great to see the engine running. Thanks for the bore-scope view of the insides.

You got smoke! I appreciate your knowledge, depths of knowledge and your passion is contagious! Thank you.

Good job as usual and am really looking forward to some sine waves.

Very cool genset and I'm glad you got it running.

Awesome video. Really helped me visualize how a Diesel engine works. Thank you!

Awesome info on injection pump. Thanks a million!

Very cool mike! Please keep us posted on this thing as you make progress with it! Would be cool to see a video of you actually installing it in your van too, I'm curious what the install will look like!

That was amazing. I cant thank you enough for making this video. I have an old MDJE in my Old Trawler. It was great seeing how you bled it as it is a nightmare to work on in the boat. 1000 thanks.

Good job! Enjoyed seeing the old girl live again.

Best onanist on youtube. Love your vids.

Welcome to the diesel Fantastic Journey.

Many years ago Detroit Diesel still part of General Motors at that time had on display at their booth in the Miami Boat show an iconic marine generator. It was a 6-71 genset out of Jacques Cousteau's research vessel Calypso. They claimed it had 30,000 hours and still ran! It looked like it had a 100 000 hours and spent its life in a salt mine. I wonder what happened to it when Roger Penske bought Detroit Diesel. Mike, right up your alley, chase it down!

Great vid. Looking forward to episode2.

Just bought an old boat with almost identical genset and it needs some work. Unburned fuel coming out the exhaust and running loud. This video is very helpful to me. Thanks

Sounded great Mike, great job.

For all your concerns about the bore it seems to run just fine! Love how you show us how these things actually work, I actually gave the screen two thumbs up at one stage.. :)

I posted a video to my channel of my MDJE 3 days ago. What a coincidence lol. Thanks as always for the videos! Working on my 6.354 video tonight as well.

Really enjoyed this video. I have this exact generator in my boat.

Very good clear concise English. Excellent one man photography. Correct terminology of components. Mechanic lingo

Great video Mike. I just love old diesel engines and the way they run. Didn't sound bad at all for the first start in who knows how many years. lol

It does my heart good to see you use line wrenches!

Hello Mike,nice little unit.

Very nice mike. It’ll be nice to see if it works out and how you go about setting it up in the van. Thanks bud for another great video.

Aw man, I want it back now!! Sound great buddy!! I hope it works well for you 👍👍

Great video! Just found your channel and I'm going to be back watching more!😉😉

You have a very good knowledge, great work, thanks.

Nice job 👍

Could be a good unit for your application, hope to see more of this project

I do hope that "rusty and crusty Onan" will be saved for you Mike. Interesting video, good to watch as you go along with bringing it back to life. I'm looking forward now to the next edition of this .

Good video,most small Diesel engines are low compression,so do need heat to start,and glow plugs run on about 20 seconds after they start,very unusual injection pump,but good idea,thanks again.

great video would be good to see a restoration on the engine but would be expensive by the looks of things well done

That injection pump reminds me so much of the military pumps that used to come on the MEP 002a

I've just had to pause there, that's a real decent borescope you've got there 👍

Great video Mike thanks for sharing 👍

Very interesting video.

great project, just a thought, Starter power from truck battery, wont have to worry about charging circuit, If truck Diesel fuel from truck tank, water cooling, run waterpipes parallel to truck heater.

Thanks for posting.

Love the sound of that thing.

Fascinating engineering, interesting movie thanks

You will need a cooling system. Boat engines use wet exhaust if that matters.

Thanks.Learned something new today.But that motor was underwater i think at one time.

Thanks for sharing buddy

New Ford Bronco....nice!!

The problem with Marine engines, especially ones operated in saltwater is that they usually have a water box muffler that's filled up with raw water when it's running and when the engine is shut off it's still hot and that salt water in the water muffler vaporizes and makes its way back into the cylinders through any open exhaust valves and causes corrosion if it's sat for any period of time....

That's a cool little unit :)

Great start Mike 👍👍 How do you plan to cool it if you put it in the back of your work van, run an auxiliary radiator for it?

Raw water sends sea water into inner tubes of heat exchanger then to exhaust manifold . Clean scale from inner tubes to get good cooling .All water in goes out through small ports in end of exhaust elbow. Often rust clogs up holes . Nice Onan. PS try JB weld in cylinder wall pits scratches then hone it. I have a honda 5 hp worse than that running for years on my channel . Experiment i tried worked.

I loved the older fuel test comparing the gas to diesel from the 50’s I would love to see a newer generator (diesel) consumption vs older with similar wattage outputs to see consumption if they are worth the extra computerized and harder to service by a normal person.

I'm a Jersey boy. I bet you lie down the shore, huh? I;m also a gen guy. Love the show.

Raw water is the water the boat is floating in (salt or fresh) and coolant "water" is the fluid (usually anti freeze) is what is circulating through the engine. The heat exchanger has both raw water and coolant flowing through it where the heat from the engine dissipated into the water the boat is floating in. It works just like a car radiator only it is a liquid to liquid heat exchanger rather than a liquid to air heat exchanger...

I worked on a mess of those while a marine diesel and gen tech. I am of the 'hate the magnaciter' crowd. 😂 They shook like mad but the engine was hard to kill.

Hiya Mike. Yep, yesterday was awesome, and today I have a bit more snow than in your video. Looks like we will have another warmup this week with snow again next weekend.

You are awsome!

Great video... :-)

Impressive!

I love your work and your videos. I've been working on cars and small engines for almost 50 years now (never professionally). One of my sons is a professional auto mechanic. We both agree you are a quality mechanic and a pleasure to watch. Thanks for your great work and for sharing it with us!

a little trick for rusted bolts and nuts is the try and tighten it a hair, if it the moves then you can usually break it loose.

Is it too soon to get 'excited' about an old genset? Great work getting it that far, good explanation of the inner workings.

I own several onan DJ series gensets including dja ,djb and djc my favorite is my djb 5.0 from navy subsalvage

Thank you 🙂

Looks like your MDJE is close to the same vintage as mine. If you can find the adapter plate, upgrading to the gear reduction starter from the direct drive Prestolite makes a world of difference in how it cranks and starts. You need 45-60 seconds of glow plug to get it to fire off in cold temperatures. I retrofitted mine with a chinese generator controller that had a programmable glow plug timer and ditched the 50 year old wiring in the control box completely. Good luck finding new 12V glow plugs if you need them. I'm using a Kubota BX23 radiator for cooling with an electric fan, and the belt driven Oberdorfer circulation pump as a water pump.

I hope you start with the big cat engine build looking for it

Man I want one of those little probing cameras for my birthday

Hi Mike from the UK

On your pump mounting plate, the pump on the left is a rubber impeller "Jabsco" type pump for the raw (sea) water that is pumped into the heat exchanger then into the water cooled exhaust elbow, then overboard.. Depending on which version that pump is, very few parts are still available for it. The pump on the right is a centrifugal pump for the fresh water/antifreeze that runs through the engine and heat exchanger.

This is cool

Mike, I have one of those. I put a school bus heater core on it with a home furnace blower to cool it. Mine is a 1971 with some sort of a brush and slip ring field.Can I backfit an electronic regulator?I put a new 8kW Westerbeke in the boat where it had been installed. The fuel solenoid had shorted, caused a 12 volt electrical fire, putting Mrs. Customer in the hospital for smoke inhalation as the boat suffered a lot of collateral damage. The new generator was $8000. The job totaled $85,000. Raw water is the water the boat floats in with the rubber impeller pump. Fresh water is the block coolant moved by the centrifugal pump. There was a heavy duty fresh water pump for keel cooling.

TY

How did I not get this notification

Ah 1977! Perhaps the genset powered at sound system that played some "Boston", "Kansas", or "Rush". Or since it is a marine unit, something more sophisticated like "Chic", "Sister Sledge" or "Sylvester"!

Mike, looks typical for a genset used in about a 40' pleasure boat. If it came out of a commercial boat it would look a lot worse. It may not have that many hours, possibly between 1000-2000 hours. It has good oil pressure and the fuel system is working so do a warm compression test to see what's going on. If the compression is OK and the gen side has decent output I would pull the head and check the valve gear. I could easily see where the valve lash was never set. The problem with old Onans is the price and availability of parts. I have done work on MCCK 2 cyl opposed flat head gasoline engines 4-6.5 kw 1800 rpm they were used from mid 1960's to around 1990. The shielded coil and plug wires were several hundred dollars for each piece if they were even available and that was about 10 years ago. The coil was special in that the plug wires screwed directly into the side, opposite from each. I could unsolder the inner spark plug wire and pull through solid core wire and resolder the ends but the coil was not repairable. The work around from Cummins Onan was the coil, plugs and wires from an air cooled CCK which are standby and construction gen sets. Not shielded and not needed and that package was about

If you tie it into ya Trucks Cooling system and the Tank you have Power and a worme cabine always :)

Gonna plumb the Genset into a truck heater line? That would be pretty cool, truck could preheat the Genset, or it could preheat the truck, depending on how the coolant pump was ran. Btw, ain't it lovely to be in shirt sleeves in January and February?

Have you ever tried getting an engine running and using abrasive powder in the intake to break glaze or help seat the rings. I was told manufacturers used to come with break-in powder, not sure if it was just a tall story or some truth to it?? Thanks for sharing your time and videos.

i'm would not have expected using a torch for starting aid would be so effective . i would have guessed that too much oxygen would have been used up . interesting to see.

I had an old Gravely lawn tractor from the seventies and it had the Onan CCKA motor on it. It was painted red but the inside of the fan/flywheel housing was the exact same lime green color that’s on that flywheel on your generator. Wonder if that motor started out its life on a generator...

I had one of those wound up throwing it away, I know that was dumb anyway as far as your pump the raw water pump has a rubber impeller and the fresh water pump has a brass impeller, I may have some parts for that, I know for sure I have the injector tips brand new never used them probably a little rusty by now let me know if you need them.

I was just going to mention that as valves wear, the gap should close up....then you said it.

I pulled one of those from a boat and replaced it with a battery bank & inverter setup. The boat owner got tired of constantly throwing money at it. The marine environment wasn't kind to it. Hopefully you have luck with yours.

“I’m not a welder”... I saw you weld four 5S Briggs together.

I've heard my Yanmar fuel pump is calibrated on a Bosch stand. Which are unfortunately rather rare around here. Fresh water is potable. Raw water is from the lake or ocean.

With that type of valve rocker arm could it be it wore where it pivots on the ball end of that adjuster? Or maybe over time the adjuster just backed off. Diesel does have harsher vibrations than a gas engine. And I have seen rockers on a gas engine almost wear through where they pivot on the ball.

What control panel will you update to? You said you would use a modern controller. I have the same gen on my boat.

Flame arrestor is the box on the intake.

I have a onan 12.0 djc generator. During hurricane Ida it shut down due to the throttle link rod. What happened was the link rod back out and stripped the brass threads. Do you have any suggestions what can I do to fix it. I brought it to a machine shop and they didn’t want to touch it. The part number is 150-0831. The body of the link rod also has some wear where it was rubbing but didn’t go through. I plan on putting job weld unless you have a better suggestion.

american bosch became united technologies sometime in the 1980's and licensed a lot of old american bosch designs to other companies so i'm not surprised that you saw the yanmar name on an old bosch designed injector. fwiw robert bosch (germany) was a different company than american bosch with completely different designs.