smoking 12hp kohler magnum

[PaulC 341]

I recently purchased a 1987 312a to use all year round as my mower and snowblower, it has 42 side discharge mower deck and 42" snowblower. The blower has recently been gone through and looks to be ready to go, the deck needs some maintenence which im currently doing now, the tractor itself is in real good shape but has 1100 hrs on it. The engine runs strong and fires right up but she smokes pretty good, mainly when you first get it up to full throttle, but it smokes enough that running it in my garage for maybe 5 minutes over the weekend had me and the garage pretty smoked out. My question is how extensive of a rebuild am I looking at to correct this problem? I have been thinking about and hoping I can just get a new set of rings and gaskets and clean everything up and be good, but is it worth it? will changing only the rings fix the smoking? and if so will it last long? If I dont do anything and just run it as is what should i expect long term? Any sort of info on this would be greatly appreciated.

Also considering everything above what should I run for oil? The manual says to run sae 30 in temps above 32 degrees and 10w-30 or 10w-40 in temps under 32 degrees. As I said I intend to snowblow with it so it most likely will see temps below 32 but will the thinner oil pass by the rings that much easier and smoke and burn more? My local dealer told me to just run the sae 30 all year round?

Any info and advice will be greatly appreciated, Thanks Paul

[can whlvr 991]

well there are different thoughts about this subject,but in my opinion if you are gonna rip her apart to work on her i would do a complete rebuild,with this many hours im fairly sure you will find that the cylinder is gonna be out of round and worn,i doubt that just a hone and rings are gonna be enough,maybe but i doubt it,so either be ready to do a full buildwhich will be bore,piston,rings,lap valve seats,maybe valves and most likely a rod,it seems that the rod is an issue when they get older,gasket set,polish crank and true head if needed,or just run her and keep your eye on the oil level

[Wheel-N-It 2,967]

Paul, I agree with my friend above. With that many hours turning a hydro transmission, and a mower deck or snowblower, your engine is really worn. But Paul dont dispair. the Kohler 12 magnum is an excellant flathead engine. Totally rebuilding it is a good investment. It is simple to do, or have a good mechanic do for you, and then it bolts right back in easy as taking it out.

Your only other good option would be replacing the Kohler 12 with a Kohler 14 or 16 magnum or older K engine. The older K engines are just as good as the slightly newer magnums, and both should be basically bolt in with little modificaton. I will strongly advise you to look at the 14 or 16 upgrade. The hydro transmission eats up a little horsepower right off the top, so the extra 2 or 4 horsepower plus the extra torque will really help turn the blower or mower. I have a Kohler 12 magnum tractor, a Kohler 14K, and a Kohler 16K. The 12 is very smooth, the 16 is a big thumping torque monster, and the 14 is a good compromise of torque and smoothness. Good luck with whichever way you go.

[JackC 616]

"My local dealer told me to just run the sae 30 all year round?

Probably good advice for a worn engine.

If it starts and runs good it would be cheaper to just keep running it with 30W oil and maybe some additives like STP oil treatment and keep an eye on the oil level before each use. I have a 16 that starts and runs great but has 1300 hours and burns some oil. It is not my main machine however. I have seen complete low hour tractors for sale for less money than the cost of a rebuild.

[PaulC 341]

Thanks for the advice guys! I dont have the time or money currently for a complete overhaul so not sure what im gonna do. I was told the original owner had a flat 4 acre lot they mowed with it so im guessing thats where most of the hrs came from, not sure that would have any lesser effect on the wear of the motor? When I talk with my dealer again later this week im gonna price rings and gaskets and if they are cheap enough I may just try that first. I also have a 312-8 which I think is a 1985 with the K301,but it doesnt have an hr meter so i dont know the exact hrs, but doesnt smoke at all so swaping motors is also an option.

wheel-n-it where do you expect i could find a 14hp magnum? and say a running one with decent hrs what would be a good price? and would it bolt right up to my machine?

Jack do you add an oil additive to your machine with 1300 hrs? if so which one and does it seem to make a difference?

[can whlvr 991]

if you do just rings you do have to hone the cylinder so the rings will seat properly

[leeave96 487]

Great tractor you have. I would forget the dealer and go with the advice here (but take mine with a grain of sale... )

That Kohler Magnum engine is a terrific engine and worthy of rebuilding to keep - BUT

It may not need a rebuild. First thing I'd do is pull the head and decarbon, reset the valves and clean the breather assy and make sure you have a clean air filter. If you find the bore looking pretty good, i.e. no scratches or scoring, you might be able to get away with a light hone and new rings. But I'd run it after doing doing the decarb, breather, air filter and valve adjust first and see where you stand with the smoke. Run some MMO in your gas to get a bit of top end lubrication too - can't hurt.

Good luck,

Bill

[Wheel-N-It 2,967]

Paul, the other guys have give you some good advice too. You may be able to get out inexpensively with just removing carbon from the combustion chamber, or digging a little deeper by honing the cylinder, new piston and rings, and compound the valves and seats.

Good used 12hp Kohlers will run you anywhere from $200up. 14 and 16 Kohlers are about twice that. The rare NOS K motors that come along once and a while go for $700 and up.

Dont worry or let this overwhelm you now. You are just getting your feet wet with this hobby. Since you dont have alot of extra money, first try what Bill suggested and decarbon the combustion chamber. Put it back together carefully and see if that works for you. Maybe it will smoke just a little bit. No big deal. Let that get you through the Winter till you can do more next Spring. Keep an extra spark plug on hand just in case. If you adjust the valves, take a pic of how the breather sits in the block. Do not put it in backwards or it will not breath. Also do not overtighten the valve adjustment access cover. If you do, it will leak oil and you will never get it to stop. Dont ask me how I know this (LOL).

Take your time and enjoy your Wheel Horse. After a while you will discover the Wheel Horse is the best of all the old school LAGT's.

I sure did.

[PaulC 341]

guys this is great info and exactly what i was looking for, I am very happy to be a part of the wheel horse crew haha. few more questions though

how do i adjust/reset the valves?

whats a good cleaner to use for the head and breather assy?

will i need a new head gasket? and anyone know the torque specs when reinstalling the head?

if the cylinder looks good should i try to run a hone in it to see if the rings will re-seat themselves?

and last question for now haha is , bill what is MMO?

thanks again guys

[Buckshot 1 15]

:) Very good advice from all. I would look into obtaining a K-series service manual. MMO is Marvel mystery oil. :flags-usa:

[can whlvr 991]

as recommened get a copy of the manual,i got one here somewhere along time ago,i would also recommend visiting brian millers pulling site,he talks about not needing new head gasket if you use some kind of sealant with the old one,dont quote me but i think it was a copper based sealant,very good reading

[JackC 616]

"Jack do you add an oil additive to your machine with 1300 hrs? if so which one and does it seem to make a difference?"

I did purchase some STP Oil Treatment based on Mark's recommendation but I have not added any yet. The benefit of the STP is to reduce further engine wear. The mowing season is past so I have not used the machine in awhile. I did find that straight 30W oil lasts a lot longer in the engine than 10W-30W.

Maybe over the winter I will take the head off, check for wear, adjust the valves, and see what it needs. I would not put a lot of money into it because I prefer the smoother running twin cylinder engines like the Kohler KT17 IIs and the ONAN P216s that I have.

The STP oil treatment contains ZDDP (a zinc compound) which is supposed to provide the protection that oils did in the past. The company claims the purpose of the Oil treatment is to strengthen the oil film and prevent metal-to-metal contact, and in the event of that contact, to add boundary layer lubrication form the boosted zinc compounds.

I also believe in using Seafoam in the fuel tank to help keep the carbon build up down and to absorb moisture and condition the fuel to some extent.

I try to buy ethanol free fuel when I can get it.

[PaulC 341]

Hey guys I have a update. Last saturday I pulled the head of my motor. I found a crap load of carbon which was to be expected, I found that the cylinder was not scratched or scored, and also found that the piston was not burnt. So I cleaned everything up did a light hone and reassembled hoping for the best. Unfortunately the smoking is no better and im wondering if its actually worse? I did some work to my 42" rear discharge deck over the past few days and took it home and put it on last night and started the tractor to check everything with the deck out and it smoked out my whole garage leaving me smelling like crap when I made it inside.

So now my question is this, I have an 1985 312-8 with a K301 12 hp on it, the machine is pretty beat up but the motor runs great with no smoke. Will that K301 bolt right on to my 312A which currently has the magnum? I am thinking of changing it and either leaving it or just doing it temporarily while I get around to rebuilding the magnum.

Also I was at my dads property this past weekend, where the 312-8 came from and spent its whole life and finally dragged the lawn sweeper that was used with it out of the weeds and brought it home. After about 20 mins of working it and dousing it with PB blaster I got it all freed up and starting using it. Once I hooked it up behing my rear discharge deck I was in business! Taking care of my crazy amount of leaves was a snap. The sweeper is really well built and "RED" so its got me wondering and hoping haha that its a "horse". I will try to take a few pics in the next couple days of my tractor with the sweeper hooked up and maybe you guys can help me figure out what I got.

Thanks again for all the wisdom and help!

[can whlvr 991]

yes you can put the k into the 312 with the magnum,you will need to rewire the tractor a fair bit as there is quite a differance between the k and magnum in the wiring department,starting with a different key switch,the k will have points where as the magnum has a module,maybe you could use a temporary wiring job so you dont have to wreck the wire loom for the magnum tractor,but it can be done with a little work,im sure someone will chime in that has done it

[Duff 206]

Paul, you say you did a light hone and reassembled but didn't say if you put in a new set of rings? Even with a hone, my guess (there are a ton of guys here with more motor experience than I have!) is that the old rings may be worn out and thus unable to create a good seal with the cylinder wall. As far as the motor swap. I'll bet someone will jump in and let you know how to rewire for the K301.

Duff :thumbs: