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Jr.lll

Kohler Magum 18 Rebuild

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hurleyii

Expensive is what I've been told. Cheaper to buy new almost then to rebuild any twin.i can tell you my Vanguard cost 220 for a cylinder head 3 years ago and that was dealer cost cause they priced it on what his computer said. Was like 167 I think plus the other parts I purchased. 

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Jr.lll

That you for the info, I have been considering a new Kohler command engine. Repower system wants $2600.00 for a new command that will bolt up in my Gravely 16g tractor. Again thanks for the response, Paul.

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GregB

Some others may chime in on this subject. 

Why the rebuild? 

Measured the bores and they are worn? 

To much end play on the crank? 

Lose rods?

I have read that re-ringing solves a lot if the cylinders are not worn.

Never done it just interested in the symptoms and solution, I hae one down on power waiting............

 

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Brettw

If you have an engine that blew, the rebuild can be expensive.  If not and it's a runner, it can be freshened up or rebuilt fairly reasonably.  They are, in my opinion, great engines.  As far as information on the rebuild, the Kohler site has service manuals for the M18 free for download, and it will guide you completely and in a detailed format as to disassembly and reassembly.    I would think that if the cylinders can be honed, and with what I would recommend overall, new rings, gaskets, governor gear, tune up, etc., probably less than $250.00 in parts.  If you aren't interested in the rebuild, and if it's not blown, and if you live near Milwaukee, WI  I might just know a guy who would be interested in purchasing it from you. 666

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Jr.lll

The engine is not blown, I’m having issues with the governor. Engine cranks right up, but then it starts to speed up with no throttle response. Please correct me if I’m wrong, you have to open her up to replace governor gears. I thought, if going to all the trouble to split her apart why not rebuild? Any advice or thoughts would be greatly appreciated.

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Brettw

The governor gears have somewhat of a history to fail.  Usually when that happens the parts flying around internally and the elevated RPM's cause the grenade effect.  If you are over-speeding and believe the gear has failed, then yes, you have to split the case to replace it and might as well do a rebuild.  However, first I would look to the Kohler site, look up the service manual, and it will explain exactly how to set the governor correctly.  You could give that a try first.  But I would be very careful as you still have a good engine and it wouldn't take much to turn it into scrap.  In all honesty, if you haven't been playing with the governor, and if all of the linkages appear to be connected, and the arm appears to be tight to the shaft, I would find it hard to believe the governor has just decided to quit functioning and is in need of adjustment.  The gear has probably failed.  Good luck, but it is worth checking before you tear it all down.

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Jr.lll

Unfortunately have already tried to adjust according to Kohler device manual, no change. This appears to be a expensive repair no matter what route I take, rebuild or replace. Still looking for a good used engine replacement. Thank you for your reply.

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MikeES
On 4/20/2021 at 6:38 PM, Brettw said:

I would think that if the cylinders can be honed, and with what I would recommend overall, new rings, gaskets, governor gear, tune up, etc., probably less than $250.00 in parts. 

Brett is right on.  The gasket/seal set with rings can be had for about $130, these are universal sets that work with both the KT and M engines.   With the M18 you don't use many of the gaskets in the kit as it all fits together with silicone.   I have rebuilt 3 KTs and 3 Magnums and have never had to rebore the cylinders.   And I made a KT17 series II with KT-I parts and Magnum parts.  Many are interchangeable.

Edited by MikeES

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Jr.lll

Thanks for all the good advice, plan on having engine rebuilt in near future. What is the site to get the parts you mentioned in your post? Like to have them in hand before I start. Thanks again, Paul.

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lugnard

I just went through a m20 this winter. Cam was bad and the governor. Many missing teeth on the cam gear. Picked up a good used one on ebay and the other parts I usually get from ope engines.

https://www.kohler-engine-parts.opeengines.com/

Always have had good service from them. As said not really much in parts just a bit of work since the cylinders and pistons are installed with the rods already on the crank and the block halves are together. Not a hard job, but you fit the piston wrist pins in, as you offer the cylinders with the pistons installed, to the block rather than having access to the crankshaft and bolting the rods in if there were an oil pan. Hope that makes sense but it's in the service manual.

I didn't hone or replace the pistons or rings. They all looked good and it really runs nice. Fires up better than my 1920 with the command. That one needs to crank over a bit more.

Good luck

Harry

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