I'm pretty sure it doesn't have a heat exchanger, sea water cooled. If it has a heat exchanger it will have a coolant reservoir with a "radiator cap". Good little engines. I'm in the sailboat biz and there are a lot of the one banger Yanmars on sailboats to about 25'. I'm working on one right now trying to descale the water jacket. It's also sea water cooled and 20+ years has clogged it up.

quote:

Originally posted by F_L:
I'm pretty sure it doesn't have a heat exchanger, sea water cooled. If it has a heat exchanger it will have a coolant reservoir with a "radiator cap". Good little engines. I'm in the sailboat biz and there are a lot of the one banger Yanmars on sailboats to about 25'. I'm working on one right now trying to descale the water jacket. It's also sea water cooled and 20+ years has clogged it up.

Thanks, good to know.

quote:

Originally posted by MikeinNC:
I used to work on Cummins 902 s and the water exchange system was on the block. Sea water came into a tube bundle where it took heat away from the closed system full of antifreeze. And the seawater went out into the exhaust system...

I thought you were a GMC... i miss the 41s.


To PH Paul, i don't think this engine has a bundle tube heat exchange, most likely it just used raw water through the block.

For the fuel it should go tank, water separator, strainer, low pump/filter high pump/ filter, injectors.

Check the impeller on the water pump and use a 5gal bucket with hose in it for short tests. You can rig up a radiator for longer testing. Don't let it run more than 30 seconds or so without water or you may destroy the impeller

It most likely was a 12v system but don't be surprised if the boat had some 24v stuff too.

It may not start in gear

I've been watching several boating Youtube videos lately and just watched a 3-part series of a guy rebuilding a 2-cyl. Yanmar.

https://www.youtube.com/watch?v=4mKjUBF_5kY

These little yanmars are absolutely terrific engines. And very tough to kill. I have run them in smaller boats myself for thousands of hours and delivered boats with them where they have 10K+ hours. They are normally raw water cooled. If there is not a tank with a coolant filler cap and some connections to cool the transmission its raw water. In terms of running it on the bench you just need to supply it with water to the seawater pump and collect it on the other end (that's the pipe coming into the exhaust system). Supply clean fuel through a prefilter and change the filter on the back of the engine and all will be good. They are fussy about lift so make sure your tank isn't too far below the fuel feed pump. Need some form of intake filtering can be a bit primitive at this point. Priming them is a PIA as you use the lift lever on the pump and have to crack all the fittings. If it turns over with a little oil in the cylinder I will bet money it runs just fine. Make sure the tranny has oil as well. Have a fuel shutoff in your plumbing as they have a habit of having the injection pump shutoff not work after sitting. Great project.

Thanks for the tips HRCJON, I hope to get to the point of starting it today.

I got two more repair projects dropped off yesterday afternoon that I need to get out of the way first as they're taking up the limited floor space in my garage.

My old man had this exact one-pot Yanmar as an auxiliary motor on his boat. Ran for years and years. Bit "bangy" at low revs, but smoothens up nicely when you open the throttle.
Cooling was direct sea water - on the side of the block there is a sacrificial anode which needs to be changed at regular intervals.
Good (and not so good) memories of rolling around in a tight, dirty bilge to service to stupid thing (dad would claim "ignorance" of all things mechanical and leave that to me )

My first thought was that would make an awesome youtube video if you paired it up with your ultralight aircraft. ;-)

We had a Yanmar 44 HP in our Irwin 44' sloop. The thing was an absolute tank. Other than changing the oil and filters, I don't think we did a thing to it for 20 years. Thing practically started on its own.

Link to original video: https://youtu.be/m-7wOf8qmoE

I trimmed a little too much off the front of the video, but once I got it bled it starts right up and settles down to a nice thumpy idle.

Sweet!

The possibilities are endless...

You are the man! Nice save. I'm sure you'll find something cool to do with it.

Very cool!

That's awesome

you have to get the Bert and I one lunger going:

quote:

Originally posted by sjp:
I thought you were a GMC... i miss the 41s.

I was! But we all gotta start somewhere. I was a fireman apprentice and fireman at Sta Yankeetown. We had 41431 then 41370.

The 41’s were great workboats, good range, utilitarian, but were slow for LE.

/drift

Whoever said it was a little clunky at low RPMs wasn't kidding.

Great job. I hope you find a good end use for it.

Jim

PhPaul,

I may be able to help you with that little puppy, I used to own one and worked on it a good bit. Those babies are all around the world not just on sail boats but they ran generators in a lot of out back country....

She's a little hoss.

Now here is the secret to starting one of those in cold weather... (for those that don't know it, there is no glow plugs on these) when it's cold... like in the 40's or so and the engine as been sitting... prime her and then turn her over for about 20-30 seconds then stop and let her sit for about a minute or more... then repeat.... I guarantee by the third try she'll start right up. What this does is the compression in the cylinder will heat up the head and everything else but it takes that minute or two to actually spread the heat out....

Oh, never use starter fluid of course but WD-40 is okay in a crunch if you have to, but it will eat the air filter.

Get the air out of the fuel system and it should fire right up. Sitting doesn't seem to effect diesels much. It most likely came out of a sailboat. You're going to probably need at least a group 31 battery to start it.

quote:

Originally posted by PHPaul:
Included in the pile that came with the engine was a Dahl water separator. It had been removed with a knife so I have no idea how/where it plumbs into the system.

Advice from those in the know appreciated.

The Dahl is a pre-filter. It's not necessary, but goes on the fuel supply line between the the fuel tank and the motor.