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1114 Views 14 Replies 7 Participants Last post by  Zack
So I have decided to look into swapping the Kohler Magnum18 out of my 317 into my most recent 318. The 318 engine(B43G) is going to go into the 317. I know I will either need to buy, or preferably fabricate, an adapter plate for the Onan into the 317. What all am I looking at here besides that?
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The parts to fit an Onan into the 317 are well delineated in the PC1698 section 22, although is is specifically for the P218G so there will be differences around the starter, etc.

The adapter plate is HE403-2615, and because it has the HE prefix, you may be able to get one from Cummins/Onan as well. Sit down when you learn that Deere wanted over $500 for it recently and now it shows as "no price available" so it might be NLA...

Well I don't have or even know what PC1698 is and I knew the cradle was no longer available. It can't be to difficult to make the cradle, I just need some dimensions. What driveshaft combination will this require and what wireing mods will need to be done?
Jeff, PC 1698 section 22 is Parts Catalog 1698 and then the stuff you are looking for is in section 22 under PC1698.
I mean this in the nicest way I can, but 210 posts and you haven't used JD Parts or a parts catalog to date?!?
Yes I have used JD parts. I just put in the model number, 317 or 318. I will go back and look it up the way you are saying to do it. I just thought that someone here might have done this before and could help me with what would be needed. I still have the p218 flywheel, but sold off the oil pan.

Anyone have any ideas on what will be needed to put the Magnum18 into a 318? I doubt if that is covered on the JD parts site, and I'm not having any luck searching this site for the answers.

OK, so it looks like I need to use the 317 driveshaft and adapter with my p218 flywheel. And I'll need to fab up an adapter plate and grind the front crossmember for some reason. And maybe a new throttle cable. Other than that...not much help. Nothing about the ignition system being different. And of course, everything is out of stock.
Well I'm sure you remember this thread,

As you can see it never got finished, it just turned into a money pit.

Sorry, but I just have to ask, why are you switching motors if they both run?
I wondered if you ever got it done.

I want to switch them for several reasons. Number one is the onan has 1300 hours on it, the magnum hours are unknown, but it runs strong, much better than the onan, even better than my new p218. number two is my step dad needs a 317 to tow around his baggin' wagon setup. his 317, which was my grandfathers, is now in my possession and smokes terrible. That little tractor is on its 2nd motor and has had a hard life. Its about done. I wanted to fix it, but its going to cost too much for him. So now I have 2 318s and 2 317s. I really only have the need for one! I hate to give up my baby(317) but he could really use it and I don't trust him to maintain it too well. Hes pretty hard on equipment. Soooo....I thought I would give him my 317 with the tired onan, since he will only use it 2 or 3 times a year, and I'd put the good magnum in my second 318. Confused yet? Its a mess. But it can get more complicated! I also want to swap the hydros and steering columns on the 317s because the ones in grandpas old 317 seem to be in better working condition. Grandpas old 317 can then be sold for parts or whatever. I don't want to put the money in it myself, and its taking up valuable floor space. Then my stepdad gets a 317 back, and I have my 2 good 318s.

My mom says I have too much time on my hands. I can't help it, I like to tinker. My uncle asked my mom why I have 4 tractors for such a small yard, and she asked him why he has 3 corvettes when you can only drive one at a time. He didn't say another word, LOL.
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Wow you got alot of time on your hands, but thats a good thing, good luck with your "swap-a-roo" post some pics I'd really like to see a 317 onan conversion done by someone other than the dealer conversion. The 317 onan that my dad has its nice.

Well, I need the dimensions for that stupid engine plate for starters.
well i got my new 317 home and got about half the yard cut before i noticed problems. when i picked it up i saw oil on the bottom..i asked about and he said yea there's a small leak. well as the motor warmed up it started smoking..i think a combination of oil leaking and bad rings i assume. then started loosing power as it warmed up..let it cool down then it was fine till it warmed up again and running high and low, high and low... coil? who knows. the guy said he put 200 into a tune up at a jd dealer..not true as the air filter isnt new..cant enen see through it. and plugs wires dont look new..im assuming when a dealer tunes up they replace coil condenser, plugs wires and all that stuff. condenser looks new but thats it. being an older guy i trusted he was good for his word. i've bought and sold enough stuff to know when you get home there will be something the person didnt tell you but he could have been a liitle more honest.i may be looking at sinking some money into this. besides that it cuts and drives nice...
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Those 17's have a habit of loosing the rear seal on them. Seen a lot of them where the seal just spins in the bore. Not to bad to change them .
roy, do you make anything of the motors rpm going up and down..up and down after its hot? after awhile it would only idle..if i gave it throtle, it just kills. think its electrical?
Neil, it could need a carb adjustment,a tune up, or maybe the cooling fins are blocked on the back side of the engine. That is a big problem with the 17's. They pack up a lot of junk on them. If your tossing oil out the back it doesnt help either.
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