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Kohler Engine

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Go to the Kohler site.  They have PDF's of very detailed service manuals.  These will give you all of the info you need to know to completely overhaul your engine.  Parts?  That might be another discussion, but I find tht e-bay or your dealer may have everything you need.

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Take photos as you disassemble the engine so you have a reference as you go back together.  Also the folks on this forum have hundreds or years of combined experience.  SO, if you do have a question you can post it here.  You should have an answer in short order.





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Before even considering this, follow BrettW's advice and download the service manual from Kohler.  

I have done engine work on a number of K series Kohlers over the years,  mostly on old IH Cub Cadets.  After getting the manual, I would evaluate the engine before you commit yourself to spending a few hundred bucks on machine work and parts. Pull the tins and accessories, but not the flywheel, drain the oil and remove the head and crankcase bottom. Check for metal in the bottom of the oil pan. The old Kohlers can smoke and run for years if you keep oil in them and don't run them too hard, but will seize after being overheated or run out of oil and will leave telltale large particles or even parts of the piston in the muck left over after draining.  Here are a few common things to check for to evaluate the engine before completely dismantling it:

  • With the piston near the top of the bore, sight down the gap between the piston and bore, and try to rock the piston back and forth. If the piston can be rocked back and forth more than a minimal amount, be prepared to rebore the engine
  • Look for deep scratches in the bore, 
  • A lot of oil on the top of the piston, with oil fouled spark plugs indicates a badly worn piston and rings. You will usually see this with the preceding items as well. 
  • Remove carbon buildup from the top of the piston. If the piston in there is oversize, there will usually be a stamped mark indicating the oversize. The maximum oversize is .030.
  • With a light film of oil on the cylinder wall, turn the engine over by hand. It should turn smoothly, without backlash or grinding.
  • Check the connecting rod on the crankshaft by trying to rock it back and forth at several points as the engine is rotated. A little end play is ok, but if you can feel rocking or looseness, you are looking at either worn rod bearings or a worn crankshaft journal.
  • Check the camshaft for wear. The main issue I have found is the points lobe will often have a groove worn into it, making it impossible to adjust the points because the gap will change as the engine warms up. 
  • Pull the rod cap off and inspect the crank journal. If there is metal on the crank journal from the rod, carefully remove it from the crank journal with fine crocus cloth. If this is the case the rod is junk and there is a good chance the crankshaft will need to be reground. 

If the preceding tests found serious issues, consider looking for a better used engine, particularly if the crank journal is worn or the cylinder is worn more than .030 over. New cranks are unobtainium, and and machine work is expensive and only possible if the crank can be restored to an undersize of .010 under or the cylinder to .030 over.  If things aren't looking too bad, its time to break out the micrometers and feeler gauges. Here are the main things to check for:

  • Remove the connecting rod and piston assembly.  Make sure the rod cap goes back on the same way it came off, and pay careful attention to instructions when reassembling the engine. 
  • Check the rod journal for diameter and out of round. Spec diameter is 1.5000" -.0005" but you can probably get away with up to .0015 of journal wear, especially if you only plan to use it occasionally.  
  • Check the bore for out of roundness and taper. The bottom of the bore wears less than the top, so take your reference measurements at the bottom. You can probably live with up to 3 or 4 thousandths of taper and out of round, but any more should be bored to the next standard overbore. If you are already .030 over and have excessive taper or out of round, the only way to save the block is to sleeve it. 
  • Check the flatness of the sealing surface of the head and block with a straightedge and feeler gauges. Usually the head warps before the block, but blown head gaskets can cause pitting, especially near the exhaust valve. A warped head can be made flat again milling it or by wet sanding it on a sheet of wet or dry sandpaper on a flat sheet of glass at least 1/4 inch thick. If the head has been previously milled, make sure there is adequate clearance for the valves.  
  • Check the valves  by removing them and checking for burned seats. Minor pitting can be resolved by lapping the valves, but if the valves are seriously pitted or the stems eroded, your best bet is to get new valves and have a machine shop grind the seats. 

If you are lucky there is only 3 or 4 thousandths of wear in the cylinder and a good crank and cam. In that case get a new set of rings, give the cylinder a light honing, which will help seat the new rings. Before putting it back together, wash all the grease, small metal particles and abrasives from honing or valve lapping with soap and water, rinse with a garden hose and let dry.  After it is dry, spray the block and internal engine parts with something like WD40 to prevent rust if you aren't going to assemble it right away. Use a prelube like STP on all moving parts when you do. If you don't have a piston ring compressor, a worm drive hose clamp will work. in a pinch. Take your time, and keep the engine and your hands clean as you reassemble it. Its not that hard, but it has to be done right.  

Partswise, the best way to go these days is to get a Stens rebuild kit, which is sold by a number of places on Ebay. You will have a number of options depending on the extent of the work needed, and the particulars of your engine. If you get a new piston/rod assembly, the dipper may need to be shortened if you use a flat bottomed oil pan.It will include all the gaskets you will need as well, and they are pretty reasonable in price.  

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19 hours ago, bnolte said:

Before even considering this...

... and they are pretty reasonable in price.  

IMO, the above is a great post and think it should be easily found.

Therefore, I made it an "Article";  although I credited Bruce for writing the post, I'm hoping a moderator can change the "author" of the "Article" to Bruce.  Thanks in advance for doing this.

Edited by PhanDad
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Ended up ordering the balance gear bearings.  Should be completely back together by the weekend.  New piston, rings, honed, washed and flushed with Dawn and hot water, looking good.  


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About the balance gears, I guess am in the camp of either removing them or replacing the needle bearings. I decided to leave them out of the last K301, which I rebuilt to replace a completely worn out engine in a Cub 129. The engine vibration wasn't too bad, but more than a K241 which never had balance gears at all. 


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