Build generator with Yanmar engine

Scott & Heather · September 04, 2017, 07:54:17 PM

I was just gifted a yanmar 3 cylinder diesel out of a John Deere golf ball picker upper. Has about 1400hrs on it. Oil looks good, runs solid ran it today, radiator looks brand new actually the whole motor looks a lot newer than the body of the golf ball picker upper. Since this is free to me, can I buy a generator head for this and build a generator? I've converted two buses so I'm handy lol.

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windtrader · September 04, 2017, 08:48:53 PM

Cool!

I think there is more to bolting on a motor to an alternator. If you find a generator with a busted motor, that would make the most sense. It would be a lot to cobble together all the non motor components to make your own generator.

Since I've just been knee deep in generator problems, learning more than I care. In my case, a Generarc RV 8Kw liquid cooled diesel, some features are designed into generators. For example, the typical engine coolant temperature and oil pressure switches do more than light up bulbs in the dash; they also shutdown the generator. An electronic control module coordinates this shutdown and manages other functions; this is probably unique to generators. Power from the alternator is monitored and controlled via the module. Load and engine speed are managed as well.

Scott & Heather · September 04, 2017, 09:09:53 PM

Hmmm. Interesting. Probably way too much work to do this. Maybe I'll just keep the tractor. I realized today actually that it's a greens mower. Has hydraulics and everything. Would be cool to add a plow to it or something. I'll figure out something to do with it.

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TomC · September 04, 2017, 11:26:52 PM

To make it simple, just find a 12kw belt driven gen head. Belt drive it with a cogged timing belt and off you go!

richard5933 · September 05, 2017, 01:26:41 AM

I just did the same thing as you are attempting. It is quite possible and not really that difficult.

We had a Kohler generator attached to a Perkins diesel. Mice destroyed the generator and control box. I was left with a perfectly good engine.

After a bunch of phone calls to the tech at Wrico, I was the proud owner of a 13kw generator head which bolted directly to the end of the Perkins. Then I wired a set of Murphy switch gauges to control the shut down of the engine in case of high temp or low oil, and installed a key switch to run the whole shebang.

The big factor that will determine if this will work is the measurement of your bell housing. The generators can be ordered with adapter rings to enable them to bolt directly to most standard size bell housing/flywheel combinations. The tech at Wrico can send you a chart of the standards they can fit. The measurements you are concerned about are:

1) Bolt pattern on and of bell housing. Both the diameter of the bolts and the number of them.
2) Diameter of the depression in the end of the flywheel as well as the bolt pattern.
3) The offset between the surface of the bell housing and the surface of the flywheel depression.

The end of the generator will have a flex plate. This is nothing more than a few thin pieces of metal which are bolted to the shaft on the generator. The flex plate bolts directly to the flywheel. It sits in the depress which is on the surface of the flywheel - sort of where the clutch pack would go in a 'normal' engine set up.

The flex plate is connected to the part of the generator which spins. You will mount it to the flywheel first. The portion of the generator which is stationary (the outer casing) mounts directly to the bell housing through the adapter ring.

There are no brushes on the new generator heads, so they sit pretty compactly and don't take up as much space.

Once you've got the new generator head bolted on, all that's left is to cram all the new wiring for the controls into the box on top of the generator. I've got mine all working through a Murphy Switch. Turn the key, and the Murphy Switch engages a relay to provide power to the governor, radiator fan, fuel pump, and hour meter. The Murphy Switch I have allows 30 seconds to crank and build oil pressure. They can be ordered with a 15 second delay or with a manual bypass button for starting. Once the engine starts and builds pressure, the Murphy Switch just sits there until there is a problem. If the needle in either the oil pressure or engine temp gauges hit the set point, the Murphy Switch cuts power to the relay, thereby shutting down the system. Easy peezy.

Right now I've got mine set up with parallel key switches in the generator bay and inside the coach so I can start in either place. There is a toggle in the generator bay which will send power to either key switch so that it can't be started accidentally by someone in the other area if you're working on things.

The one thing you'll have to figure out on your particular engine is how to govern the engine speed. It will be really important that you have an accurate governor and can set the engine to hold a speed of 1800 rpm. The frequency of the power (and the voltage to some degree) are determined by engine speed, so this has to be held constant.

I can send photos if you would like. The one posted shows things just before I installed in the bay.

Scott & Heather · September 05, 2017, 05:55:07 AM

Wow! Fantastic write up Richard! Ok, I'll chat with Erich more about this. After all the engine is indeed free. I won't have a single moment to work on it until Christmas because I'm on the road. But I can start gathering bits and pieces and info. Thanks so much again. I may be poking your brain more soon.

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richard5933 · September 05, 2017, 08:10:39 AM

Quote from: Scott & Heather on September 05, 2017, 05:55:07 AM
Wow! Fantastic write up Richard! Ok, I'll chat with Erich more about this. After all the engine is indeed free. I won't have a single moment to work on it until Christmas because I'm on the road. But I can start gathering bits and pieces and info. Thanks so much again. I may be poking your brain more soon.

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Just let me know what you need. Wrico can get you set on the generator head. For the Murphy pieces I went with MurCal (I think that they are the California distributor for Murphy). They have an excellent tech support team that can walk you through that end of things.

I did not install an auto start setup. Perhaps I'll do that later on, but for now I wanted to be in control of what happens. If you want auto start I believe Wrico can help.

Richard

Zephod · September 05, 2017, 09:10:49 AM

I've got one of those cheap Chinese wind generator things. No vanes etc. I've been toying with putting it with a model airplane engine to make a mini 12v generator. The only thing that stops me is I don't have a spare engine and given the thing would be such an experiment, I'm not prepared to buy one.

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thomasinnv · September 05, 2017, 09:14:45 AM

Wrico has an auto start control system that can be adapted to work with most setups. It is a stand alone and not brand specific. I have one on mine, just flip a switch, easy peasy.

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Scott & Heather · September 05, 2017, 04:38:39 PM

Nice, auto start is on the list for sure. I'll need to price out the head and conversion parts to be sure it's worth it for me but again, free engine with relatively speaking low hours so I can't imagine i should pass this by

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lvmci · September 05, 2017, 05:48:21 PM

How great Scott, you get to choose the generator KW output and physical size for a decent price, lvmci...

DoubleEagle · September 05, 2017, 09:00:06 PM

Martin Diesel in Defiance, Ohio (Southwest of Toledo) builds their own generator units, and they use Yanmar engines. They have parts for old & new Yanmars. I have had a generator of theirs since 1996 with no problems. They have mated their generators to other engines such as Perkins, as well. Their number is (866) 868-9911.

thomasinnv · September 06, 2017, 06:07:27 AM

Scott do you know the hp rating on that engine? Hp will dictate the size of head you will want to mate it up to. (iow, limit kw output)

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thomasinnv · September 06, 2017, 06:12:20 AM

A friend of mine (died about 7 years ago and was in his 80's then) built a generator out of a 3 cyl kubota from an old tractor and a belt driven 8k head from harbor freight. Got over 20 years out of it before having to replace the power head. No electronics just a simple key start.

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Scott & Heather · September 06, 2017, 07:12:44 AM

Crazy cheap way to do it...pulley size dictates RPM. Makes sense. I don't know the HP rating yet. I'll look at the serial tag closer later but from what I've read it should be in the 16hp range. I only want 7000 watts give or take. Don't have huge power needs. I've been running for several years on 6000 watts without issue at all.

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