782 Onan Engine swap - need some advice for the driveline

[MichaelTJD60]

Hello everyone. Long-time lurker but first-time poster. I apologize in advance for the long-winded post.

I recently purchased a CCC-built 782 (784) tractor from a friend. It has its original Kohler KT17 series II engine with a broken rod, and I have a low-hour Onan P218G engine out of a JD 318 sitting on the bench ready to go in it. You might think I'm crazy, but I'm a big fan of Onan engines and I've always thought it would be a cool idea to Onan-swap a 782, so I've decided to tackle this project.

I was thinking of beefing up this tractor with a spline-shaft hydro pump from a Cyclops. But I'm not sure which type of drive line would be best for what I'm planning to do. I was thinking of using a JD 318 driveshaft with u-joints because it was designed to fit an Onan engine and a splined-shaft pump, and because the P218G engine has the solenoid-shift starter and has to be raised up in the 782 frame. So a straight drive shaft might not exactly work. This would be sort of like doing a CV driveshaft swap out of a newer Super.

But I'm not familiar with the Cyclops pump and I don't know if it uses the same exact spline pattern as a JD 318 pump...so I don't know if a 318 driveshaft would fit. Here are some pics of the 318 spline shaft...do the Cyclops tractors use the same shaft?

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I thought about just swapping the 318 pump into the 782, but the swash plate/linkage arm is on the opposite side, and I'm not sure what it would involve to swap the arm over to the other side. Should I just stick with the original 782 pump and drive shaft, and try to find the flywheel adapter plate from a 982? In order to use the original driveshaft, though, I would have to cut a hole in the engine mounting plate to make the engine sit level because, like I said above, the P218G doesn't sit flat due to the shape of the starter.

Thanks in advance for any help you can provide. Sorry if I sound confusing.

[ol'George]

Welcome to OCC.
I'm thinking you are making work for yourself needlessly.

Sell the 318 parts/onan and pick up a good M-18, it bolts in literally.
Or some fellows repower to a newer OHV V twin engine.
While I have respect for onans, they are expensive when it comes to parts.
With the m-18, nothing is cobbled, modified or bastard-ised.
just my thoughts and I have built a few Johnny cash Cadillac's.

[ccpullin]

Welcome!
If I was installing this Onan in a 782 I would change the starter to one without a solenoid so the engine can sit where the Kohler did clearing the fuel tank and making the drive line straight (like a 982), then use the 982 Onan engine drive hub.

[jaynjeep]

I would think "IF" the earlier 982 style starter will fit and work you will be a whole lot better off.. I think the P218 and the B48 Onans are close cousins if not darn near identical.. so it should be almost plug and play with the right parts from a 982..

I agree the Onans are beasts and have a sound of their own.. I have several and love them... My only complaint with an Onan is parts availability and darn some of them Onan parts are 4 times what a Kohler part is!

Good luck.. I think it will be a nice unit if you get it all worked out!

[Sam Mac]

If you want to use the Deere drive line swap the Deere pump input shaft into the Cub pump.

[Oak]

As always, the best way to go is to use a CV style driveline. Another member sent me a PDF of the Onan adapter plate needed for the CV setup. I can email anyone a copy if they want it and I'm sure Jeff can make them for us.

Sell that starter on Ebay and go grab one of these high quality precision Taiwanese starters. I put one on my 984 with a P220 and it works great.
https://www.ebay.com/itm/STARTER-FIT...S!-1:rk:9:pf:0

I would just use the rag-joint setup for the driveline unless you are putting a ton of hours on the machine. I would probably also replace the rear coupler (Jeff makes damn nice ones) and rag joints and you will be good for another 500 hours. Don't make the drive shaft until you get all the new parts bolted up and then measure for the length of the new shaft.......ask me how I know that.

Oh, one more thing.....

[darkminion_17]

Originally Posted by ol'George

Welcome to OCC.
I'm thinking you are making work for yourself needlessly.

Sell the 318 parts/onan and pick up a good M-18, it bolts in literally.
Or some fellows repower to a newer OHV V twin engine.
While I have respect for onans, they are expensive when it comes to parts.
With the m-18, nothing is cobbled, modified or bastard-ised.
just my thoughts and I have built a few Johnny cash Cadillac's.

Good info, easy peasy is the way to go.

[goonpeden]

I put a Onan from a 318 in my782. Had no issues installing it. Only issue is cant use it to mow grass due to the pulley on the pto is about 7 inches and crankshaft is about 1 7/16 inch. Makes killer vacuum but burned up idle pulley on deck after about 30 minutes of mowing. Called Outdoor Plus about one of their units but was told they dont make a unit to fit crankshaft that size. But gotta love the Sound and Torque of the Onan.

[MichaelTJD60]

Originally Posted by ol'George

Welcome to OCC.
I'm thinking you are making work for yourself needlessly.

Sell the 318 parts/onan and pick up a good M-18, it bolts in literally.
Or some fellows repower to a newer OHV V twin engine.
While I have respect for onans, they are expensive when it comes to parts.
With the m-18, nothing is cobbled, modified or bastard-ised.
just my thoughts and I have built a few Johnny cash Cadillac's.

I've owned and worked on a couple KT17's and M18's and I haven't had the best luck with them. But the M18 and v-twin swaps seem to be very common and I'd like to do something a little different...the whole Onan swap was the main reason I wanted to do this project. I've had good luck with almost every Onan engine I've worked on, and I think they are just as tough as the Kohler's (IF they have had proper maintenance).

Originally Posted by ccpullin

Welcome!
If I was installing this Onan in a 782 I would change the starter to one without a solenoid so the engine can sit where the Kohler did clearing the fuel tank and making the drive line straight (like a 982), then use the 982 Onan engine drive hub.

I do suppose that would be the easiest way to go. But swapping the starter also means I'd have to swap the oil pan because the starter mounts to the block on the P series Onan's, but it mounts to the oil pan on the B series. If I have to swap the oil pan I will, though. Nothing for this project will be plug-and-play.

Originally Posted by jaynjeep

I would think "IF" the earlier 982 style starter will fit and work you will be a whole lot better off.. I think the P218 and the B48 Onans are close cousins if not darn near identical.. so it should be almost plug and play with the right parts from a 982..

I agree the Onans are beasts and have a sound of their own.. I have several and love them... My only complaint with an Onan is parts availability and darn some of them Onan parts are 4 times what a Kohler part is!

Good luck.. I think it will be a nice unit if you get it all worked out!

The B48G and P218G blocks are the same, so the oil pan and starter should fit. I have had great luck with Onan's and I think they are just an awesome engine all-around. I've kinda gotten used to the price of Onan parts at this point...I think this is the 6th or 7th one I've worked on. I've lost track. lol.

Originally Posted by Sam Mac

If you want to use the Deere drive line swap the Deere pump input shaft into the Cub pump.

Would that involve taking the whole pump apart? I've never had one of these Sundstrand pumps apart before.

Originally Posted by Oak

As always, the best way to go is to use a CV style driveline. Another member sent me a PDF of the Onan adapter plate needed for the CV setup. I can email anyone a copy if they want it and I'm sure Jeff can make them for us.

Sell that starter on Ebay and go grab one of these high quality precision Taiwanese starters. I put one on my 984 with a P220 and it works great.
https://www.ebay.com/itm/STARTER-FIT...S!-1:rk:9:pf:0

I would just use the rag-joint setup for the driveline unless you are putting a ton of hours on the machine. I would probably also replace the rear coupler (Jeff makes damn nice ones) and rag joints and you will be good for another 500 hours. Don't make the drive shaft until you get all the new parts bolted up and then measure for the length of the new shaft.......ask me how I know that.

Is that adapter you speak of for installing a Super Cyclops-style CV driveshaft? If I decide to keep the original straight shaft, I was planning to replace all 4 rag joints anyway.

Originally Posted by goonpeden

I put a Onan from a 318 in my782. Had no issues installing it. Only issue is cant use it to mow grass due to the pulley on the pto is about 7 inches and crankshaft is about 1 7/16 inch. Makes killer vacuum but burned up idle pulley on deck after about 30 minutes of mowing. Called Outdoor Plus about one of their units but was told they dont make a unit to fit crankshaft that size. But gotta love the Sound and Torque of the Onan.

Are you running a B series Onan? That should swap right in. I was just thinking about the PTO situation actually...looks like my only choice is to use a 318 PTO clutch because the crankshaft is much larger than a 982 Onan engine. I have seen someone install a 318 clutch on a KT17 before, and it seemed to work fine.

[MichaelTJD60]

I know everyone is eager for pictures. I actually just picked up the tractor today, I feel like a kid in a candy shop. This thing is in great shape, it's got 853 original one-owner hours, came with a decent 44C deck and the paint is almost flawless...just wish it had the grill and side panels, but I can pick those up cheap. Turns out it's actually a Series I KT17 and not a Series II, so that would explain the broken rod.

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