682 Loader Tractor Kohler Command Engine Swap

[mgonitzke]

I mentioned in another thread I was about to do this, and have finally almost started. Too many things going on at the same time. Anyway...

I pieced together this tractor and loader about 10 years ago, moved it Kansas to use around the yard this past year, and fixed up a bunch of stuff on it, including new hydraulic pump, hoses, foot control for the transmission, and a few other things, only to find the K321 I put in it is very tired and burns tons of oil. So, I started looking for a different engine and wanted to go a bit more modern. Found a Kohler Command CH15 single cylinder engine about an hour from me awhile back, bought it non-running for $50 along with the driveshaft from the donor CC 2155 tractor, and so far, all I have done is clean it up, replace the the flywheel end crank seal, put in new air filter, oil and filter change, etc. Today I spent a few minutes wiring in a relay to ground the magneto, since the 682 is wired for battery ignition.

I bought a used JD STX38 muffler (that lawn tractor uses the same engine in a vertical shaft configuration) that will work with an elbow on the exhaust. Next, I need to make some spacers to raise the engine to the correct height while still using the original twin cylinder engine mounting plate. Then, it will be time to pull the K321 and sit this in there and start figuring out all of the details.

 

[mgonitzke]

Slow progress...made some aluminum spacer blocks to bolt the engine to the 682's original engine mount plate. They are 1 3/8" thick, as the CH15 crank centerline height is 7/8" less than the KT/Magnum/Command V-twin, and all of those engines use ~1/2" spacers with the mounting plate. All of the holes lined up, and the engine is bolted to the plate. The next step is to remove the loader bucket, all of the front sheetmetal, and the K321, and then set this in and see how things look.

I also temporarily mounted the muffler to see how that's going to work. I hope to only have to make slight modifications for it to fit.

 

[mgonitzke]

Accumulation of a couple weeks of progress...before putting the engine in, I made an extra piece to make the firewall a bit more airtight.

Then, I made a duct to seal off the space between the flywheel shroud and firewall. These two things combined will ensure the engine only draws in cool air for cooling, instead of recirculating hot air from the engine compartment.

I had to get a longer choke cable and cut it to length. The original one was about 8" too short.

I welded part of the CH15's original exhaust pipe to the outlet of the used muffler I bought. That was a lot less modification than I expected.

Also installed the cut-down 2000 series driveshaft and fan.

Everything electrical and fuel-related is hooked up. The last step here is to make a muffler shroud to make sure all the hot air moves out the front like it is supposed to, and then fire it up and hope it works!

 

[mgonitzke]

Last week I finished the muffler shroud and got it to start, but...the magneto fails open after about 5 minutes of run time. So, ordered one of those and will be tearing this half apart again to fix that.

 

[mpatterson]

What other engines could you use in this frame? What is the biggest Kohler that would fit, maybe a CH640 or so? Thinking of empowering my 982??

 

[agitch]

I've got a new CH740 in my 1864. Was identical size to the CH18 now sitting on my work bench.

 

[mpatterson]

I've got a new CH740 in my 1864. Was identical size to the CH18 now sitting on my work bench.

How much of a hassel was it to install? Modifications needed to it, the tractor frame, drive line, etc. Did you buy the CH740 specifically speced out for Cub, or was it removed from another tractor? Was debating either a 640 or 740 as a transplant engine. Price new from Kohler is crazy expensive though!!

 

[agitch]

How much of a hassel was it to install? Modifications needed to it, the tractor frame, drive line, etc. Did you buy the CH740 specifically speced out for Cub, or was it removed from another tractor? Was debating either a 640 or 740 as a transplant engine. Price new from Kohler is crazy expensive though!!

Since my 1864 already had a command in it, it was a simple swap. No mods. I had to put a sleeve on the pto shaft to get it the right diameter. I've got a 682 and when the kt17 craps out i'm gonna put the CH18 in it. I'll use an engine mount plate and driveshaft from a 1863/1864. I'll get the pump adapter from Jeff in PA. I'll use a relay for the wiring due to the command needing a kill wire. I'll use the exhaust heat shields from a 1863/1864 as well.

 

[mpatterson]

Just curious Matt, what are you using to cut out your parts with - do you have a plasma cutter or you farming it out to a local shop to do?

 

[mgonitzke]

The sheetmetal parts were cut with electric shears, hand shears, or a nibbler, depending on the shape.

 

[slufkin]

How do you like the foot pedal hydro setup? My wife loves foot pedal controls so I've been thinking of making that change.
How much was just pulled from a donor tractor and how much was fabricated?

 

[mgonitzke]

How do you like the foot pedal hydro setup? My wife loves foot pedal controls so I've been thinking of making that change.
How much was just pulled from a donor tractor and how much was fabricated?

Love it...only way to have a loader tractor, in my opinion.

The only thing from the donor machine (3000 series) was the forward and reverse pedals, which were extensively modified. I made the rest.