kohler K 321 overheating

Friend of mine has a 73 JD 140 mower .What the problem is when u run it real hard or when it is in a hard pull the muffler gets cherry red and the engine sounds like it loses power. Thanks again. Scott
 
It's running to lean, could be the carburetor is out of adjustment or it's sucking in air some where other than the carburetor. Check the gasket between the carburetor and the block, check that the bolts are tight and adjust the carburetor.
 
It's running too lean. Open up the high speed needle on the carburetor. Those engines need fuel as part of their cooling system.

You might also take off the engine shroud and clean out all the mouse nests and dried grass in there to improve air flow over the head. Then clean out the crud and grease that accumulated in the fins on the block.

Synthetic oil might help.
 
In addition to checking carb/carb settings check the flywheel key,same may be bent/sheared changeing ign timeing.
 
You might also check to see if mice haven't built nest under the shrouds blocking air flow around the cylinder causing heat build up. Seems several of my motors suffered from mouse nest this year. I normally throw a few moth balls in the engine compartments, but never got around to it last fall.
 
The timing is off. Point gap is 0.020". Use a feeler gauge to get them close. Then use a timing light to finalize the setting. Use OEM points and condenser only.
 
(quoted from post at 18:12:48 07/03/14) Synthetics are NOT to be used in a Kohler K engine.

Strange, I have been using 10W30 synthetic in my K301 powered gravely for 5 years or so. No problems.
I switched to it to fix a valve sticking open when warmed up problem.
It is a 72 model, never been rebuilt.
 
Hi please explain the reason for no synthteic oil?
Per Kohlers FAQs you can
10W-30 (Command Oil) is recommended for Command, Courage, Command PRO, Command PRO CS, Triad OHC, and Aegis engines for temperatures above freezing (32°F, 0°C). SAE-30 is an acceptable substitute if temperatures are above 50°F, 10°C. K-Series and Magnum engines should use SAE 30 (Magnum Oil) above freezing. 5W-20 or 5W-30 can be used in all engines when temperatures are below freezing. For more complete oil specifications refer to your owner's manual. For optimum performance, Kohler's special blend oils are available from your KOHLER dealer.

Synthetic oils meeting the classifications listed in the owner's manual may be used, however oil changes still need to be performed at the recommended intervals. To allow the piston rings to seat properly, Kohler recommends operating a new or rebuilt engine for at least 50 hours on standard oil before switching to the synthetic oil.
 
Just went through this with a Briggs twin V engine. Key was parcialy sheared. The special washer on top of the flywheel was not tight enough anymore. New key and put a big lock washer on it. Smoooth running now. Also blow out all of the crud in, over, and under your shrouds.
 
Most of you guys are applying current technology to a 40 year old engine.

-It was born with 30wt. oil and if 30 wt. is what is in there, the oil is NOT the problem.

-It has coil/battery ignition and flywheel location or the flywheel key or absence of same DOES NOT affect the timing of this engine. although it may vibrate less if the flywheel key is intact.
Timing is controlled by the plunger working off a lobe on the camshaft. The plunger operates the points.

The poster needs to adjust his valves, perhaps lap them in again, or grind them, decarbon the head, and richen his high speed fuel mixture and see if that solves his problem.

He may have an excessively worn engine, or worn parts on the mower that are robbing power. It is also hydrostatic which consumes lots of the availble power.
Remember, this engine is rated at only about 1/2 the hp. of most current riding mower engines.
 
Given the yr of tractor it's possible eng has solid state ign,however it could go either way on type of ign as poster didn't give spec# of eng,just trying to cover all base's.
 
Don't rule out solid state ign,if eng has same flywheel/flywheel key will affect timing,given the 73 yr of tractor ign system could be point type or solid state,I had a 69 wheelhorse charger 12 tractor I bought used with orig eng & same had solid state ign which I later changed to point type when coil went bad.

While working on a neighbor's K301 from early-mid 70's I also found that kohler eliminated the tapped holes/plunger hole in block & you couldn't do a point conversion on eng & had to stick with solid state ign,this is why when someone posts a solid state ign problem on a K series & someone suggest's converting to point type ign system the first thing I tell them to do is check on left side of cam gear cover for 4-5 holes in block for points/point cover & plunger in addition to making them aware as to ign sw/wiring issues that will have to be resolved BEFORE rushing out & buying a conversion kit & also downloading a K series service manual so they can do a static timing on ign system as there may not be a timing hole in flywheel cover/bearing plate which was also eliminated on later eng with solid state ign.
 
Here's what I found when my Wards garden tractor was over heating when plowing my garden. I( bought new in 1971. This was 6 or 7 years ago. It has always had 30wt oil used in it. I had to remove the cylinder head so I could snake some of this mouse nest out. I also used air pressure. I thought I may have ruined the engine. I'm still using it. I don't keep cleaning rags in the mini barn where the tractor is kept. Hal
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