Kohler Magnum 20 swap into a D Series

[Hodge71 664]

Anyone have any info on the feasability of this swap? My 18 auto has some serious engine issues all of a sudden and I would love to do this swap if it possible with little modification. I found a Magnum 20 close to me from a Cub Cadet. It only has 420 hours on it and they blew the hydro. He's parting it out and I can get the magnum for a decent price. Any help would be appreciated. 

[MarkPalmer 81]

A lot of it depends on the specs of both engines.  I'm sure it can be done, but the "little modification" part might be a problem depending on several factors.  You are talking swapping a K482 with a M20.  Both engines have similar external dimensions, but the spec numbers can dictate the crank length and diameter, especially going from a Cub application to W/H, and physical fit in the 18 auto is important as you use both the PTO and flywheel side of the crank.  You would have to go and look at the M20 prospect, and measure things up.  I'm not even sure if the crank height is the same.  The ignition systems are different, but it's not hard to change from a battery/points ignition to a magneto.  Myself given the choice to modify the tractor to use a used M20 or rebuild my K482 I would likely rebuild the K482.   

 

-Mark-

[Hodge71 664]

Mark,  

 

The problem I'm having is finding a complete kit for a K-482. Plus the fact that in not really 100% positive it has enough stones to push my 60 inch deck. I adapted 60 incher from a 520 to fit on my 18 auto. When its running its tapping the governor just by engaging it. High thick grass has  got it bogging pretty well. Ive been looking for a complete K-582 or 632 for years now to no avail. Theres a member on here that has an 18 auto for sale in the classifieds for 8 grand. He put a 27Hp Kohler Command on it but he refuses to respond to my emails. I just wanted some info on doing the swap as far as what engine to buy and that was it. I guess its not something he's inclined to share.

[multihobbyguy 35]

There is a D on ebay that is re-powered with a Magnum 18 so it looks like it can be done. You can search with the phrase below in ebay. Maybe the seller would be kind enough to respond to your questions.

 

1973 Wheel Horse 18 HP Automatic Garden Tractor Mower

[MarkPalmer 81]

The K482 was under-rated, and if working right should be able to run a 60" deck with little difficulty.  I don't think that replacing it with an M20 will give you enough power increase to be real noticeable, but if the used M20 is cheap and will fit than I would go for it.  There are several other re-power options with new engines that can significantly increase the power, but you will be looking to spend $1500+ to do so.  Rebuild kits (pistons, rings, gaskets) for the K482 are available from Rotary, rods are still avaialble from Kohler even in undersize.  The K482 is a real good engine, one I wouldn't be too quick to trash out. 

 

-Mark-

[JamesBe1 82]

I have been considering the same thing.  I have two dead K482's.  One has a broken crankshaft, and the other has a severe oil leak that I will need to pull the crank out to fix (it didn't run that well anyway).

 

I used to have a site bookmarked that would give you the correct engine to buy for whatever tractor you put it.  Do you think I can find it again?  Nope.  The nearest I can come is this:

http://www.repowereng.com/

But these guys don't to Wheel Horse/Toro.  If anyone knows where it is, please let share it.

 

Anyhow, If I can find it, I will certainly post it.  It might be on one of my other computers.

I would like to know how this works out.  I do know that different variants of the kohler engines had different dimension crankshaft PTO's.  That has made it difficult to find a suitable replacement from a JD.  I don't want to shell out the money and find it won't fit.

 

Err, I think this was it:

http://www.smallenginewarehouse.com/Repower-Old-Equipment/Wheel-Horse-D180-Category/

Edited May 30, 2013 by JamesBe1

[JamesBe1 82]

Jeff, this might be worth checking through:

 

 

I haven't had a chance to search it for the engine that you are considering, but it might be worth it.

[Trouty56 567]

I think Mark is correct when he says the 482 should handle a 60 inch deck.  They can turn a 60 inch rear finish mower just fine.  I think the 482 is easier to rebuild than a single cylinder...

[MarkPalmer 81]

I don't honestly know why so many will jump right in to rebuild a Kohler K single, or fiddle-fart with damaged valve seats on Onan Performers, yet shy away from rebuilding K482/532/582's.  All they really are is 2 K singles working opposite of one another on a common crankshaft.  That single piece iron block/cylinder casting is about the toughest thing there ever was on a twin, they are even stronger than the Magnums or KT Series II's.   These engines are not aluminum throw-aways or iron boat anchors.  OK, you do need either a strong back or a cherry picker to horse them around, maybe that's why so many hate them

 

-Mark-

[Hodge71 664]

Im definitely not scared to do the rebuild Mark. I just have no experience honestly. I have rebuilt 4 speed transmissions, my 5 speed in  my Jeep, plenty of Mopar engines but just never really delved into a small engine before other than carb work. Plus the fact that I havent found a decent small engine guy within 75 miles of me.It seems like anyone I speak to in my circle around here says nobody does good machining work anymore. I know a guy that had a 16 Hp single Kohler last year and it cost him $1200. Frankly that scares the hell out of me, I figured twice that for my 482 just to be . I have no doubt that the K482/532/582 are truly bulletproof engines , but no matter how good they are, if theyre not done right, they'll blow up too. Thats the last thing I want to do. I'd be much more comfortable doing a rebuild under the tutelage of a pro thats willing to teach me.

[MarkPalmer 81]

There is nothing particularly special about rebuilding the K482.  The biggest problems I have seen with these are worn rings and valves/seats needing re-facing, very basic stuff that will cause the engine to lose power and seem tired.  If you take your time, follow the manual and do all the procedures methodically, there should be no problems rebuilding one of these.  The worst things people do is not taking the time to measure the parts accurately and spend the money that needs to be spent to replace what is worn out or have machined what needs to be machined.  You see where guys do the $50, “redneck rebuild,†on a filthy bench in their garage that consists of deglazing cylinders and putting new rings on yet they overlook actually measuring the cylinders, pistons, or the crankpins or checking anything else and then just throw the engine back together.  It’s nonsense like that which usually causes an engine to fail in very short order.

If you have successfully rebuilt a car engine or any sort engine before, I wouldn’t give a second thought to working on the K482, it’s actually a fun and very worthwhile engine to dig in to.  The small engine shops around me suck to the point I would never trust them to do so much as change a spark plug for me.  A good automotive machine shop is the place to hunt down, if you know guys with race cars around your area they can point you in the right direction.  These shops more often have guys who are engine enthusiasts who will take the time to do machine work right.  Mower shops are usually more interested in just pumping repair work out the door.  (No offense intended to the good mower shops out there.) 

 

-Mark-

[Hodge71 664]

Well this put a whole new persective on things. I wrench on a couple cars. A dirt mod and an asphalt sport mod. I have an engine guy I can contact who is primo. I have no idea why I though small engines were some kind of voodoo that a regualr engine guy wasnt equipped to machine. At least I know I should be able to handle it with some time and effort.I have micrometers and verneer calipers but I guess I better get a good set of bore gauges before I start things and see if I can locate a rebuild kit for the 482 once I see the internal condition of the engine and crank. I hope the pistons and bore are all good so I can just hone the cylinders to a nice crosshatch and throw new rings in her and do the valves and such.I have never lapped valves before I'm sure its not rocket science if I take my time. Thanks for all the info up to this point Mark    

[MarkPalmer 81]

That you own a micrometer says you already know what needs to be done.  I just measure bores with a telescoping gauge and the mic, it works good.   As you’ll see when you take it apart, it’s not a complicated engine at all.  It’s almost easier to work on than a lot of air cooled engines just because it’s bigger.   I believe there are some sellers on E-Bay who have the Rotary rebuild kit for the K482, but you need to know if you have to overbore or not to get the right size pistons/rings you'll need.  If in question about what might need replacing, just strip the engine down to the short block and have a auto machine shop evaluate it.  Doing most of the dasassembly/assembly work yourself, I'm thinking with machine work and parts you might get one of these engines done for around $600-700.00, and that's with everything necessary to bring it to the condition of a like new engine. 

 

-Mark-

[wheeledhorseman 574]

You're keeping us all in suspense Jeff, what is the dysfunctionality that ther kohler is suffering from?

 

I know what you mean about being a bit freaked by small engines even with a track record of rebuilding bigger stuff. First encountered it when I had to rebuild a Kawasaki single for my son's dirt bike years ago when he was in his early teens. Silly really but I remember the feeling well.

 

Looks like we can look forward to another informative thread if you go ahead. With two Ds now I'm sure my time will come at some point where I'll have to rebuild a Kohler twin.

 

Andy

[MarkPalmer 81]

Someone at work told me the K482 uses the same pistons as the 10 HP K241.  I haven't had time to confirm this, (sorta makes sense as 24 is half of 48 for the displacement) but definitely something to check in to when you are hunting down parts.  Nothing to do with me, but there is also a K482 being parted out on Fleabay from a D180 right now that has a good looking set of the style D forged Mahle pistons, standard size. (The crank and cam off that engine look to be in good shape too.)

 

-Mark-

[Hodge71 664]

Andy,

 

the dysfuctionality is that the engine was very tired and had blue smoke from the beginning. It was hammered before I got it and I could never get it to run long enough to figure that out. Last year after I did the complete rebuild of the hydro pump and motor, rebuilt the carb and did the exhaust I could get it to run for around 15 minutes. I replaced the coil and the condenser. Same issue but found it to be the points hanging open after 15 minutes of running. Replaced the points and it still did it...hung open after 15 minutes. It belched black smoke like a diesel pulling tractor when I engaged the blades on the 60 inch deck and bumped the governor before I would even drive. I could mow but had to go very slow in thick grass. I was majorly bummed at its lack of power considering I heard so many pros say that this engine was actually better than the P-220 Onan for torque and power. It gradually got better as the more I mowed with it in the fall and there was quite a few times where I plowed snow for well over 2 hours with it never shutting off but still belching smoke under load. Well then I had an exhaust issue midwinter and had to take off the pipes. Since then I can't get the right cylinder to seal to the elbow no matter what. Pretty happy with the way it ran in the winter even with the black smoke and leaking exhaust, I was looking forward to mowing this spring. Well I can even get it to run. It starts and goes for about 15 seconds and then stumbles just belching black smoke something fierce. The stumble becomes worse until it shuts off. If I put the choke on the stumble gets better but eventually shuts off. The fuel pump is brand new and shotts fuel 5 feet if I disconnect it from the carb. Its definitely not starving. I reset the carb to factory and tried again to no avail, same symptoms, same result. Pulled the carb and spent another 30 bucks on a rebiuld kit from Mr toro down the road here...same symptoms, same result.

 

I'm just so sick and tired of this thing. I did a good quality resto on a tractor and adapted that 60 inch deck from a 520 to fit ander and I cant even use it to mow with. I just was hoping to find a good engine that has a good right side exhaust port that doesnt leak and belch black smoke so that I can truly enjoy mowing with my tractor. Its so beautiful with that big 60 under her and I cant use the darn thing.

[pfrederi 17,741]

Jeff:  You frequently mentioned black smoke...usually an engine that is worn will belch blue-white smoke.  I know you have looked at the carb and fuel pump...but have you done a leak down test on her?  (checked the valve adjustment?? Cold specs are .008-.010 intake .017 .020 exhaust)

 

Let me know if you need a leak down gage i will send mine to you.

Paul

[Hodge71 664]

Paul,

 

I have not done a leakdown test. Nor would I even know where to start honestly. I have never done a compression check on it either. I guess maybe I should start there before throwing the baby out with the bathwater. It does smoke like a fiend and it is definitely black smoke. Very little blue/white to it. Thats why I focused so much on fuel and carb thinking black smoke meant rich mixture. I though for sure it was getting too much fuel. Even after all the investigation work I still need to do something about the exhaust elbow leaking. If you remember I broke my ear off like you did. The only problem is the j-bolt fix you came up with just will not work on mine. I can't get it to tighten enough to seal without bending. I need another plan for that..... 

[MarkPalmer 81]

The symptoms actually don't sound that bad, as Paul mentioned it just sounds like an overly rich running condition.  Sometimes carbs just get to the point they are shot, and no rebuilding will help them.  On this engine it's easy enough to just pull the heads and give everything a good look-over, clean up the carbon and check the bore condition and valves/guides.  Also....

 

This might sound funny and hard to believe but it happened to me a lot when checking these engines and KT's years back.  It can run the way you are describing on one cylinder.  Many times we got these and unknown to the owner one of the rods was broken, but the engine would start and run and sounded ok, it just smoked a lot and had little power to speak of and no amount of fussing with the carb fixed the problem.  Just something to look for when the heads are pulled- make sure both pistons move.   Missing one cylinder the K482 essentially becomes a crappy running 10 HP K241.   

 

-Mark-

[JamesBe1 82]

I hear you guys about the irrational fear about rebuilding small engines.  Heck, I still get it.  Dunno why, but it gets less every time. 

 

I find the hardest part is finding a good machine shop.  The last one I used charged me about 280 to turn the crankshaft.  I know it's important work, but I have a hard time swallowing the price.  I wouldn't even think of taking a block to them.  I would probably have to take out a second mortgage.  That's one of the reasons that I end up doing a redneck-rebuild (funny term, I had never heard it before )  I would really love to have both of my K482's blocks redone, but finding someone who isn't gonna charge me out the wazoo is holding me back.

 

I'm no stranger to micrometers and most gages (I've worked on precision instruments all my life).

 

Oh yeah, like Mark says, these things will start and run easily on one cylinder.  It took me a few days of troubleshooting a poor running engine till I took one of the heads off and found that the piston wasn't moving.  What a shock that was.  They start and run, but can't handle any load.  That was what was happening to an engine of mine that seemed to be blowing fumes out of the carb.  I think I posted a video of it here.

 

Jeff. I got a bore-gage I can loan you if you want.  Also, a ring compressor and maybe a couple of other speciality tools so you don't have to go buy them.  It's the least I can do for all of your help before.

[Hodge71 664]

Well I can tell you I have heard this thing chug on 1 cylinder before. I put new plugs in it and had a bad Champion right outta the box.  Its not doing that now. The sound on 1 jug was totally different than that I am experiencing now and the black smoke was much worse. I'll yank the heads and satrt there with an inspection of the head and valves. I guess I should get a set of head gaskets before I do that as the heads have silcone squeezed out in between the heads and block. It made me nervous last year so I kinda left well enough alone. If I could find myself a nice c-160 or 16 auto I could tear this thing down with no pressure then and do it right. 

[Trouty56 567]

Mark is right about the 241 vs 482.....pistons etc spec the same....

[pfrederi 17,741]

Paul,

 

I have not done a leakdown test. Nor would I even know where to start honestly. I have never done a compression check on it either. I guess maybe I should start there before throwing the baby out with the bathwater. It does smoke like a fiend and it is definitely black smoke. Very little blue/white to it. Thats why I focused so much on fuel and carb thinking black smoke meant rich mixture. I though for sure it was getting too much fuel. Even after all the investigation work I still need to do something about the exhaust elbow leaking. If you remember I broke my ear off like you did. The only problem is the j-bolt fix you came up with just will not work on mine. I can't get it to tighten enough to seal without bending. I need another plan for that..... 

 

 

Leak down test isn't hard... you do need compressed air.  I have the instruction for the gage if you are interested.  Get the cylinder to TDC Lock the engine (Engage PTO with a good load on it)  apply compressed air see how fast air leaks out (gage tells you that) and  where it leaks out Oil filler== Rings, Carb = intake valve, exhaust= exhaust valve.

[chrisd200(inactive) 55]

Honestly, sounds like your carb is shot. The extremely heavy black smoke along with lack of power under a heavy load sounds like the the engine is drowning in fuel. As Mark mentioned above, sometimes a carb gets to the point of being beyond salvageable. As a previous owner of a small engine/mower/tractor repair shop, we encountered this problem a lot. You really need to do a compression and leak down test on that engine to verify its internal condition. You can buy the gauges at your local NAPA store. Your engine may be ok. You may simply just need another carb. I too went to the trouble of adapting a NOS 60" deck for a 520 to my D200. It cut beautiful and was worth the effort but it really worked my K532 in moderate to heavy grass. My engine checks out fine so that always confused me as the tractor runs a 48" deck, 50" tiller and pulls plows with very little effort. Oh well. Good luck friend!

[wheeledhorseman 574]

I'm probably the least experienced of all the guys chipping in here - I cut my teeth with the first Kohler, a K301, just two and a half years ago now but I sure learnt a lot including that a Kohler will continue running, or doing its best to run, when based on all previous engine experience it shouldn't be running at all. I got the non-runner going and was well pleased with it until I got a deck to go mowing. Sure, it burnt some oil, you could smell it but little visible signs in the exhaust, the problem was lack of power to mow particularly up hill. What I should have done in the first place was take the head off as you can tell a lot from what you find.

 

What I found was that the head gasket had been blowing for years to one of the stud / bolt holes and had burnt away a grove in the head that was too deep to remove on a surface plate. The exhaust valve had a track line across the face, again too deep to remove by lapping even with course paste. Replaced the valve but as I didn't have a spare head I did a deluxe redneck job patiently filling the grove in the head using weldthrough primer on a tiny brush building up til it was above the surface then let it harden for a couple of days before using a surface plate. I was surprised how long this bodge held up for. I mention it because you mentioned silicone showing? If I understand what you're saying then it sounds as though PO has done a 'redneck special'! I'm sure someone will jump in if I'm wrong here but you dont use any sealant with a head gasket.

 

Black smoke is usually a sign of overfueling as has been mentioned already and you say you've used a rebuild kit but did it include a new main jet/emulsion tube and the long mixture needle? If not then it's worth checking these are in good condition and any tiny pinholes in the needle are clear. Someone will chip in if I'm wrong here but if the compression is low then fuel isn't going to get fully burnt even if the carb isn't too bad. The fact that there is a governor that will open the throttle as the engine bogs down will tend to compound this and can lead to smoke. Just a thought.

 

Because it was an experimental repair I used an aftermarket head gasket but later when I got a replacement head I used a Kohler gasket as these have the fire ring, something I havent seen on any of the aftermarket gaskets over here.

 

One of my famous ramblings I know, but there may be something in it that helps.

 

Andy