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update #2- engine overheat - K 321 no spark now.

7K views 14 replies 7 participants last post by  Mackie 
#1 ·
Ok after trying to reset the points over and over again, I found that the contact on point breaker was loose and I could not get the exact gap .020. In the meantime I took apart the head, and rechecked the valve to tappet clearances, went to top dead center and readjusted the clearances. Reasembled the breather plate properly, and got the engine running again real good 3600 RPM the hole nine yards, and then the point gap went again, must have thrown the timing off, it stalled and the engine was so hot you could fry an egg on hood of tractor. Is this normal reason to make engine so hot?? or do I not have the carb set correctly (3 1/4 top screw and 2 1/2 bottom screw?)?? After I reset the valve to tappet clearences conducted multiple leakdown tests, and I got readings from 40% to just outside of green area in the 45% range, so the reseting of the valves made an improvement (was 70% before valves were reset.) I bought a new set of breaker points (kohler product this time, the last one came with rebuild kit...junk). I will try to install the new points tomorrow and report back. Any help would be greatly appreciated as to what is causing the engine to get so hot. I cant even touch the dash tower!
 
#2 ·
Please understand that I don't keep a diary on who is who and what they are doing or have done to their tractor or engine.

Overheating can be caused by incorrect valve timing, ignition timing, fuel mixture, plugged cooling fins on the barrel, rodents nests in the cowling that restricts airflow, plugged or block intake screen on the front of the engine where the clutch is. The Kohler Service Manual (found in our Library) is your source for specs and procedures. If the engine ran smoothly at all speeds and idled nicely, then I would not suspect any carb issues.
 
#3 ·
Sometime muffler over looked as source of engine over heating. Restriction of heat flowing freely cause heat. Timing point problem could be pin sticking that pushes point open remove pin clean by mixing CLR and half water in cup leave pin soaking overnight CLR bathroom product removes calcium lime rust this may be over kill pin can be clean many ways.
 
#4 ·
Do you still have to the correct carb on this or did you change it?

Do you have the correct amount of oil in the engine (the amount the manual says vs. waht teh dipstick indicates?

Hot hood doesnt surprise me but I dont know how hot is HOT???????

Is timing supposed to be at 0 degrees?

What fuel are you burning in this?
 
#5 ·
coalcracker, have you figured out why your engine was overheating? I ask because I think my K321 is doing the same thing. After 10 minutes of riding around cutting the grass and a few minutes of idling, the muffler assembly is 488 degrees F. The head was just under 300 degrees. I do not know if this is considered normal that is why I chimed in here to see how you made out. The temp out here was 70 degrees. I also noticed that my engine will suffer from "run on" once in a while after I idle it down and then shut if off. It almost wants to spay running for about 5 seconds. I did "mess" with the carb but we dont want to go there.
 
#6 ·
These older engines were made to run on 91 research method octane leaded gasoline and the crap gasoline that we get now with ethanol and an octane rating arrived at by a different method is way lower in it's effectiveness in older engines. The net result is a leaner mixture which runs hotter. With an adjustable high speed jet, the air/fuel mixture can be changed somewhat to enrich the fuel. On all piston engines the incoming air/fuel mixture is intended to provide some cooling to the overall engine cooling. Humidity, incoming air temp, and altitude also have an effect on engine operating temps and performance. Lead was added to gasoline to promote even burning. Now that there is no lead there are additives needed to reduce the uneven burning but not to the level of leaded gasoline. Many small engine manufacturers had to make connecting rods stronger and increased the diameter of the rod journals to deal with the uneven burning characteristics of unleaded gasoline. Some didn't do this until the mid to late 70s or 80s. Unleaded gasoline causes a hammering, power reducing, temp increasing effect on the piston in both the compression and power stroke of two and four stroke engines, and then they throw in 10% ethanol which increases the nasty effects!!!
On any engine with a mechanical governor, the throttle position changes what RPM range the governor will operate in. When the throttle is reduced to the idle position and the engine is shut off, as the RPM decreases, the governor will open the throttle to an extent. This introduces air/fuel into the still turning engine and the heat still in the engine can ignite this fuel and cause the engine to run on some after the spark is stopped. Sometimes this unburned fuel travels into the muffler and gets burned quickly causing a loud bang. Onans are famous for this but my Vanguard will do it too if I shut it down too soon after a long run.
When I repowered my 448 from a B48 to a P218 I noticed a dramatic increase in the temps on the hood and exhaust system.
Bob MacGregor in CT :mrgreen: :mowlawn:
 
#7 ·
Thanks for the info Bob. The one thing I never learned was to how to properly adjust a running carb. I understand how but I just dont have the ear for listening to them. I did some tuning on mine today and I used the engine service manual but I cant make any progress when the directions tell you to turn the screw until the engine RPM decreases and when I do it, nothing happens other then the engine backfiring and popping. I think I got it close though and I will be ordering a few tune up parts for it tomorrow. Once those parts are in I will then recheck the tip the plug since I like to use that as my "tuning tool"
 
#8 ·
It isn't easy to do on an engine with a governor. As the RPM decreases from changing the mixture the governor wants to respond by opening the throttle some. I suggest to set the carb high speed jet to the book setting plus 1/8 to 1/4 more turns and test run the tractor under load and up a hill to check it's increasing load response. The idle jet setting is fairly easy to notice where it evens out as long as the idle RPM is close to spec.
Bob MacGregor in CT :mrgreen: :mowlawn:
 
#11 ·
Stewart said:
If you don't get much effect from screw adj,then it's likely time for a carb boil. :thumbsup:
Yes, for sure the carb must be clean, with the correct float level setting, and the spark timing must be close or spot on!! Clean air filter and no fuel supply restrictions like a dirty fuel filter and/or a plugged fuel cap vent!!! Clean and correctly gapped spark plug too!!!
Mad Mackie in CT :crazy: :wave: :mrgreen:
 
#13 ·
Im seriously considering putting a diesel in my 446. As for the 224, I will keep the Kohler until it gets to a point where is just not worth it. I will keep playing with it per the manual and see how smooth I can get it to run. Im may even pull the carb off and give it a good cleaning but I need to order parts before I pull it off.
 
#15 ·
Stewart said:
Bob

Do you use a timing light on Kohlers?
You could if you marked the flywheel correctly and could see the mark thru the screen. It has been years since I did any service work on K series Kohlers. The flywheel may already have a timing mark and a reference mark on the blower housing, I don't remember. For years I used a timing light to assist in troubleshooting. I just removed it from my portable test equipment box as I haven't used it in years. It is an inductive pickup type with a 12,000 RPM limit as I have done some high RPM timing checks on engines that required it. I just looked thru my Ingersoll version of the K series service manual but no reference to timing specs or marks. A Kohler service manual may get into more detail.
Bob MacGregor in CT
 
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