Kohler magnum 20 exploration

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dag1450
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Kohler magnum 20 exploration

Post by dag1450 »

Let me repeat myself a little.....in another thread i asked the question about installing an Onan p220g in my 2072 worker. I saw one on CL cheap. That engine does not sit well with a couple guys who had some real trouble with them. So that being said im looking into the rebuilding process of the magnum. Over the last year i have done some very minor research into this but never went any further than a few internet searches....and the underlying response to those searches has been to re-power it with some new fuel sipping latest and greatest... Honda, Command, or Briggs. The minumum cost for just the engine seemed to b around $1700. I even got side tracked into these NOS two and four cylinder military engines. lol

Anyway... Big Mike you r up! Could u give me some details on your rebuild...did u send it out...was it running before u started the process...how many hours on the engine...did it need crank work...did u use all kohler parts or aftermarket?.....approx total cost? Stuff like that would b good to know. I will post info as i find it. Thanks Dave

:roll: Oh Mike......Im sure Tom wants to know....did u use the manual? :lol:
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.

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Farmallgray
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Re: Kohler magnum 20 exploration

Post by Farmallgray »

I would suggest you go to Kohler's website and download the service manual (for free) then read through it carefully to decide if it is something you would like to tackle. I have rebuilt dozens of K-series singles and several opposed and V-twins along with a few Briggs engines (not to mention several car and farm tractor engines). I always have the manual open and follow it page by page when working on pretty much any engine.

Cost will be easier to figure once you tear is apart and measure the tolerances. If it turns out to be out of your price range, your only cost is the
time you spent taking it apart.
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SWilliams
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Re: Kohler magnum 20 exploration

Post by SWilliams »

You can find the service manual and a rebuild guide from Kohler in this thread. viewtopic.php?f=8&t=6593
Owner of 129, 1641, 1863, 1864, 2263 (1863 W 22hp engine!) 2084 (2) and a 2284.

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BigMike
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Re: Kohler magnum 20 exploration

Post by BigMike »

Dag, I'll do my best to fill in the blanks.
I got my 2072 from another member in non-running condition. Something had happened internally and someone started to tear the tractor apart and just stopped. I pulled the engine apart and found the governor gear had come apart and (I believe) part of it got into and broke the cam gear.
If I remember correctly the crank journals were within spec so I did not have the crank ground.
I had to buy Kohler parts as there were no aftermarket major internals.
I used Kevin at Pipestone Small Engine and will only use him for any machine work I have......he is so good I would suggest you send him your parts for machining.
Kevin had a good used cam and the balance of the parts came from Mike(RIP) @ H.E. Long.
I assembled it myself.....with the manual :lol:
The only slightly un-nerving thing about this build was setting valve lash by grinding the valve stem otherwise it's like any other Kohler build.
Parts and machine work was about 1,000.00
Hope this helps.

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vince_o
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Re: Kohler magnum 20 exploration

Post by vince_o »

I did my 18 some years back. I didnt have to split the block, as the eng was over heated from mouse nest and wore the rings. I took my jugs off and went .020 over. New rods pistons and rings. One thing with this eng I will always remember is that you cant get a torque wrench on the jug nuts to the block. If I remember it 10 ft lbs, so its not much. And if my thinking is right if you over tighten them it throws off the valve lash. Also as the aluminum and cast move, over tight isnt good.

I always use the book if I can. I work with a couple of guys that have been doing small eng work all their lives. When it comes to oul pans closer plates, they dont use books. These guys Im talking about are wheel horse guys and they love their onans. After 3 years of working with them I think Id have the onan over the mag, did I really just say that, lol

But you need to tear down the mag, measuer everthing and weigh your options. Good luck please post pics as you go. Cause Big Mike just looks at the pics! Lmao
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dag1450
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Re: Kohler magnum 20 exploration

Post by dag1450 »

Thanks guys! Let me start by saying....I have the factory manual and have read it over several times in the past year. It is very detailed and nice pics too! Thanks Mike for filling in the blanks on your story. Ouch that $$$ is gettin up there. So is this Keven guy local to you...or is he a world renound small engine rebuilder? Yesterday i looked at a rebuilding kit..and parts on a "pats small engine" website. The kit seemed to have pistons, rings, and gaskets $400. NO: Seals, rods, bearings, governor gear, valves, tappets......! This week i hope to call around about machine work.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.

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dag1450
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Re: Kohler magnum 20 exploration

Post by dag1450 »

Yea Vince...i do remember seeing (in the GOOD BOOK) an offset wrench/bar thing to go around the jug.
So... Big Mike is a "picture" reader? Good to know going into this project! Thanks for the heads up :lol:
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.

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BigMike
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Re: Kohler magnum 20 exploration

Post by BigMike »

Big mikey went all the way through 4th grade so he can read big boy books :lol: .....run Jane run :lol:
A GOOD machinist makes or breaks a build, if you have a good one you cherish him......if you have a half assed one you make up for him. Kevin is the real deal....he will tell you the straight poop! From the sound of it Engine Mike is also the real deal and maybe closer.
The bottom line is YOU are putting it together......do the parts measure up?......are the clearances right?.....if so it will run and live, if not it MIGHT run and it MIGHT live.

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bbaker
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Re: Kohler magnum 20 exploration

Post by bbaker »

Another option and one I have planned for some day is to find a real low hour vertical crank engine. I found a mag 20 vertical with 200 hours on it I plan to use the cylinders etc off of to rebuild/build a 20 for my 782 as I'd like to have a little more power than the 18 provides. I'll still be out a gasket kit, and hopefully the couple cranks I have won't need turned. I could use the vertical crank but the pto end wouldn't work for anything.

If I tore into a magnum I'd always put in a new governor gear. Those seam to be the common failure point.
Cub Cadet, John Deere, New Holland, bobcat, Chevrolet, and Harley Davidson just a few brands I'm proud to own.

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dag1450
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Re: Kohler magnum 20 exploration

Post by dag1450 »

Yep..good idea Brian! Thanks. I have been keeping... lets say one eye open for vertical 20s. Haven't seen one yet. I do see the Kohler 18s everyday on cl....whole tractors for like $200-300 bucks. A good fresh 18 i bet would have more power than my worn 20.... but im not going down that slippery slope. In the spring i need every horse i can get for the 60 inch! Then i would have an 1872....and they dont bring as much for resale....if i ever would :lol:
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.

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bbaker
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Re: Kohler magnum 20 exploration

Post by bbaker »

For a long time I considered building my own tractor until I found the 3K series that had essentially everything I wanted. With that in mind....You could also use a command engine. It would be a bolt in affair with a few parts from a donor Cyclops. I really like the Commands, and those engines seem to be easier to find than magnums, especially magnum 20's.

My plan was to use a 782 frame, with the Cyclops power steering and front axle, and a command engine with dual hydraulics. But my 3240 has everything I just described and foot controlled hydro so I don't feel the need to build my own tractor any longer. :)
Cub Cadet, John Deere, New Holland, bobcat, Chevrolet, and Harley Davidson just a few brands I'm proud to own.

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bbaker
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Re: Kohler magnum 20 exploration

Post by bbaker »

Ok I just read your previous thread. Forget I mentioned a Command... :)
Cub Cadet, John Deere, New Holland, bobcat, Chevrolet, and Harley Davidson just a few brands I'm proud to own.

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