Thermo King / Isuzu motors for generators

   / Thermo King / Isuzu motors for generators #1  


Elite Member
Dec 6, 2013
Southern Alberta, Canada
4410 and F-935 John Deere, MF 245
So a while ago I was given 4 Thermo King motors and 1 Isuzu. The deal was that I make one into an emergency generator for their farm and I could do what I wanted with the others. 1 TK motor is supposedly an overhauled long block complete with an injection pump, oil filter etc. One had never been used on the farm and was still complete as a refrigeration unit. That one I've stripped of all refrigeration components and I managed to get it running yesterday.

The last two TK's were in used on the farm as lift pumps for flood irrigation. One I can't bar over so I don't know if I'll be able to get it running and the other one turns over so we'll see.

The 5th motor is a 3 cylinder Isuzu that was also used as a lift pump. It's loose but I haven't worked it over yet.

All the motors produce around 29 hp.

1) What size of generator? There is so much conflicting advice. Any where's from 750 watts / hp to 1 kva / 2 hp. I know there is a difference between watts and kva. Some explanation on that would be good. Right now I'm looking at 15 - 19 kva. Is it better to have the generator a bit over sized for the motor so that the generator has less of a chance at being overloaded or is it better to have a smaller generator on a larger motor so that the motor would never really lug down and you would be able to generate quality electricity.

2) How many amps would be adequate? This is basically emergency power for a fairly large farm. I realize that 29 hp isn't enough to run the whole farm. If he wants more power to run everything he can buy a pto unit for the whole farm and just switch to this one for the house and shop for the evenings/night.

3) What brand of generator? Who do I deal with and who shouldn't be trusted? How much should I worry about thd and what thd should I look for. I know I need a 4 pole or more because the TK units are governed at 1800 rpm. I also need single phase and the ability to generate 240/120. I read somewhere once that Northern Tool or similar outfit at one time made a bolt on generator for these FK units. I haven't been able to find any or any information on them either. That would be the ideal solution as it seems like they bolted right up to the FK bell housing.

Any advice or experiences that you have would be appreciated. I probably haven't even asked all the right questions so if you want to go there that's ok too. I'm in no hurry to get these done (Read that I can wait for a good used generator) but it's a nice project for these Corona days.
   / Thermo King / Isuzu motors for generators #3  
I have a TK/Isuzu DI 2.2SE that I picked up a number of years ago with the same idea. Still haven't had time to get around to it.

In my research there are a couple things to consider:

- SAE 6 flywheel housing
- Non standard flywheel
- Governor might not be sensitive enough for genset duty.

I would recommend you figure out what engines you have to aid in finding parts for them. Isuzu and Yanmar are common engines for TK units.

SAE 6 single bearing alternators are not the easiest thing to find. They do exist, but are almost a custom build and tend to come at a premium based on the prices I have received.

To use a single bearing alternator, the flywheel will need to have the pins pressed out and you'll need to drill the flywheel to a SAE standard pattern to accept the alternator drive plate.

I haven't confirmed this yet, but I think the flywheel depth is not standard and you'll need about a 1" spacer to close that gap.

My current thinking is to use a two bearing alternator:

164B 11kw Double Bearing Generator Alternator Head | Central Georgia Generator

Buy an SAE 5 bell housing and SAE 5 to SAE 6 adapter:

Generator SAE Bellhousing Front – Generator Parts | Central Georgia Generators

Lastly, an SK bushing to attach the shaft to a flywheel adapter:

Generator Bushings – Generator Accessory Parts | Central Georgia Generators

You'll need something to bolt the SK bushing to.

My thought is to take the compressor drive coupling, bore the center out of it and machine in a taper to match the SK bushing.

Another option is to find an SAE stub shaft:

SAE Stub Shafts | Hayes Manufacturing, Inc.

Locate some pulleys with SK bushings and belt it up.

Personally, I dislike the last option the least, but it's kind of a down and dirty solution.

Hopefully that gives you some ideas.

Please let us know what you end up going with and how it works out.

   / Thermo King / Isuzu motors for generators
  • Thread Starter
I have the Thermo King motors from Isuzu.

I only have one compressor drive coupling out of the 4 TK motors. I kept the mounting flange off of the AC compressor and was going to use the drive coupling with an SK bushing to make a drive shaft. If I pilot the drive shaft into the center of the flywheel, use the modified drive coupling/ SK bushing and bore the mounting flange for a bearing then I should have something strong enough to run a generator with belts if I so choose. The reason I'm considering this is then I can mount the generator above the motor and keep everything inside the Thermo King motor housing. There would also be room for a reasonably sized fuel tank inside the housing. Then everything would be inside a relatively small foot print cabinet for ease of storage.

The owner of the motors wants to mount his generator on a set of wheels for portability. The irrigation pumps were all driven with drive shafts so to do the same with a 2 bearing generator would work ok. The flywheels already have drive plates for the drive shafts mounted.

The 3 cylinder Isuzu comes with an sae bell housing and flywheel. I haven't measured the size yet but I don't think there is going to be an issue with purchasing a one or two bearing generator that fits.
   / Thermo King / Isuzu motors for generators #5  
I LOVE my 12.5 KW Isuzu/Onan. SMOOTH as Silk. But it's the largest in a range of several and my preffered backup is a 7.5kw.

IF, and that's probably not ever going to happen, I get another engine with busted genend, I would try and slow it down, maybe to 1200rpm and have a generator wound to accept that speed to maker 60hz. One might have to adjust the governor.


START of Isuzu 12.5 Project. Was told Genend was toast, so I ripped the whole thing apart and was going to buy a STAMFORD end, when I realized it all worked. Started to figure out the adapter plate, because Onan has their own, and then didn't have too.
   / Thermo King / Isuzu motors for generators
  • Thread Starter
That 3 cylinder Isuzu looks very similar to what I have.
   / Thermo King / Isuzu motors for generators #7  
Nicest runnning diesel I have.
Would be sweet in a pickup!
   / Thermo King / Isuzu motors for generators #8  
29 hp ya a very small pickup......
   / Thermo King / Isuzu motors for generators #9  
I am currently building a Reefer Engine to Generator setup myself.

With 29 HP, you could get about 19 KW. There is conflicting information out there, as technically a 27 hp engine can drive a 20 KW generator, but the best way is to see what the real gensets have. On them, they use a 32 HP engine to power a 21 KW generator. To me that is the sure why of making the hp to kw determination. depends how you set up your genset too. If you remove the alternator, and the fan, you are going to save some parasitic loads, and increase the horsepower of the engine too. That is how mine is set up. I just use a battery minder to keep the batteries charged, and then a 120 volt fan for the radiator fan.

Myself, I have a 55 hp Perkins off a Carrier Transicold Reefer unit so I have plenty of power to drive it. It is not an ideal engine as a Isuzu because they (Isuzu) were designed to turn at 1800 rpm for the chiller, and run for 50,000 hours, where as my Perkins is designed to operate at 4000 RPM and for only 30,000 hours. But I am using it because, it is what I have. And at 2607 in hours, it has a long ways to go until it hits 30,000 hours.

Myself, if I was you guys, I would get a PTO generator as it has the gearing for it already. Just throttle the engine up to match the output needed. They have a gauge that tells you when you are hitting the sweet spot, which is the speed required to get the 60 hertz. You do not have to buy new, a lot of places have rebuilt pto generators for cheap, but even new, holy crap, you get a lot of KW's for very little money since a tractor is providing the power. And it is plug and play: the generator is all wired, you just have to attach the engine.
   / Thermo King / Isuzu motors for generators #10  
29 hp ya a very small pickup......

Reefer engines are routinely used for engine replacements in pickups actually. You can read about many, many reefer engine truck swaps on youtube.