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buckdan

repower or rebuild

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buckdan

I am thinking of rebuilding or repowering my Kohler M20.

She spews out black smoke on a cold start and compression is 99 and 100psi. I found an engine replacement at Small Engine Warehouse. Its a 23HP Vanguard especially made to fit in Sunstars and the Duetz Allis 1920. Mine is a DA 1920 1691020 with Kohler Magnum20 49506.

Are these Vanguards reliable engines if im going to shell out 1650 bucks to repower? Or should I look into rebuilding and how much would that cost me? Or would a 20 horse Command fit in this tractor? A lot of questions but I am looking for some professional advice and this is definetly the place to find it.

Thanks

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Brettw

I think the M20's are great motors. However, the cost of parts to properly rebuild your engine will be in the 250-300 range, gaskets, rings, machining, etc. A new governor assembly would be wise while it's apart, and a check on the breather assembly, although the Magnum likley has the updated version. Once properly rebuilt, it will be a good long lasting engine at a fraction of the cost of replacement. Nt to mention the proper clutch assembly on a different engine. Kohler has an excellent service manual too.

Just my opinion.

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Kenh

If any "machine work" needs to be done do some research on the machine shop. I had a bad experience with two different shops on the same engine (Onan NHC 25hp). First shop ground the crank undersize and wouldn't stand behind their mistake because they did not assemble the engine. The second shop thought the oil pump was a potential problem and assembled the engine anyway. Turns out it was a problem and the motor wiped out a second set of bearings. They did stand behind that but I had to assemble the bottom end and buy a "good used" pump as nothing new is available. I have $1800 in an old engine. Looking back (20-20 hindsight;)) it would have been better to repower.

With the above said, this is probably a extreme case but it can happen.

Ken

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Brettw

Here is what I believe you would need:

Perhaps only a set of rings, that would be my guess. If the cylinder looks good and specs out, maybe just a quick hone and you would be good on that avenue. I would lap the valves.

Rings: NOS Kohler about 55 bux per cylinder

Governor gear about 40 bux

Breather assembly (if needed) about 30 bux

Gasket kit with seals about 45 bux

oil, filters (2 setups needed one for break in, then the real deal) about 30 bux

New plugs, etc. 10 bux

Cleaning supplies, paint, misc. 15 bux

I believe all of this is available on e-bay or the local dealer, some NOS Kohler stuff is still available too.

Total: about $280 machining if needed would be extra, and then you would likely need pistons and maybe rods too. But I will bet a set of new std rings would do the job. The Kohler site has the service manual you can download for free, and it is excellent as far as instruction, start to finish, on a complete tear down and rebuild.

If you choose to go that way, good luck! You won't be sorry with the finished engine, they have great torque and area a very smooth running engine, as you already know.

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buckdan

Brett, I appreciate your breakdown on parts I will need. I thank you for your thoughts and analysis of rebuilding this Kohler M20 . Do you think I would need head gaskets as well? I will definitely proceed in rebuilding this magnum 20, as opposed to repowering with a Vanguard 23 HP

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Brettw

The head gaskets should come with the gasket kit. And you will find that many of the gaskets in the kit you do not need. The M20 and previous KT series engines are a split block. The newer Magnums did not use a gasket between the tow block sides, in some cases, or the cylinders and the block, just gasket sealer (Permatex Silicone).

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Chris727

I don't think your engine sounds to be in too bad of shape as it is. Black smoke is not from oil. Its from fuel (maybe a carb adjustment). As Brett said you may not need much. Maybe if your lucky just a valve job. On the downside, if you need pistons and rods, then you would probably be better to repower as the pistons are something like $200-$250 each and the rods close to $100 each. I have a KT-17 II(same basic engine with minor differences) that needed to be overhauled. It had one broken rod. I priced all of the parts and machining and it was around $1000 and that was three years ago. I ended up finding a good used KT II. The vanguard is a great engine too and I have had good luck with them on some of my other tractors.

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buckdan

Many thanks to all of you for your thoughts and opinions regarding rebuilding or repowering my M20.

If I have to spend over a 1000 bucks to rebuild , I am sure it will be well worth the money to preserve the originality of my 1920. After all it might just need a valve job.

Thanks again to all of you, I am proceeding to tear it down and see what I need. Before I begin, I have to make sure all components are available.

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Kenh

I was curious as to the price of a short block for my 7119. It's a KT19. Prices range from $1600 to $3200:O

It looks to me if you need anything more than a ring job it would be better to repower.

Ken

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buckdan

Ken

I'll definitely consider your suggestion about the rings.

Seems I have a mind boggling decision to make.

1-Take it apart and inspect for damage and pay upwards 1000 bucks or more

2- Repower with the 23hp vanguard for 1650 bucks

3- Repower with a short block M20 for 2400 bucks

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Brettw

If you're going to repower anyway, tearing doen the old motor for inspection costs you nothing but time. If it turns out it's in need of practically everything to the tune of 1k+ I would look to a new, warranteed engine. If it is as I would expect, maybe just a set of rings and clean up the valves while you are in there, plus the other items mentioned, you will be back in business with a few hundred invested. At $2,400 I would not spend the money on a short block, that is certain.

I would take a look inside before buying a repower. It's just your time, so no harm no foul.

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buckdan

I rebuilt the carburetor last summer. It uses a quart of oil I'd say about every 100 hours. I do hear a slow intermittent grind once in awhile while engine is about half throttle. Currently still blowing snow with it and seems to have power in getting the job done. I'm just concerned about the low compression and oil consumption.

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Brettw

Although not a perfect way to inspec by any means, pulling the heads and inspecting ring end gap, visually, might help. If they obviously seem to have too much end gap to them, then you know they should be replaced. If they look close to spec (new .010-.023, used max .032) then maybe you don't have to tear it all down. You can inspect the valves at the same time, and could even lap those without splitting the case. Clean up the carbon, rebuild / clean the carb, check the breather assembly and maybe you're good to go, real cheap.

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MikeES

If your engine is using some oil it could be just the breather. These engines commonly have a breather problems especially when they wear to the point of having some excess blow by. They can build excess crankcase pressure that can push the crankshaft seals out or with the low pressure in air cleaner (especially with a plugged filter) push oil into the carburetor from the valve box, thus burning oil.

Assume your breather is good, but with compression numbers of 100 which are OK... you might have some excess blow by, and based on my experience, I agree with Brett (and I believe he has a lot of experience with the flat twins) you probably just need new rings. Most of these twins do not wear much in the cylinders, so they just need to be honed to seat the new rings.

Last fall I created a M20 from a bunch of junk engines and the gasket set with std rings was $100, from e-bay, it was a good quality set.

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buckdan

How can you tell if you're getting excess blowby, I use a precleaner around my air filter which I change on a scheduled basis. With oil soaked around the air filter I don't know how you can see blowby residue?

Seating new rings after you hone the cylinders, can you go with STD rings?

If this is just a ring replacement, shouldn't be that expensive at all.

Many thanks for your thoughts and advice.

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