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12 HP Kohler engine problems


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11 replies to this topic

#1 jmi3063259 OFFLINE  

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Posted April 21, 2011 - 01:31 PM

Hi - I have a WH C-125 with a 12 hp Kohler motor, was running fine then stopped. Did the routine check had no fire at plug so I checked the points and reset the points still no fire but that was when I noticed the the points were not opening or moving at all, upon futher investigation I found that the breaker rod that moves the points is not moving, I can move it by hand but when you crank the engine over it does not move. Any ideas what my problem might be? Or should I take it to a certified mechanic to check it out? Thanks guys for your help on this - Jim

                       

#2 1978murray OFFLINE  

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Posted April 21, 2011 - 02:13 PM

sound like something broke on the crank. I would take it to a certified mechanic unless u know how to break down a motor
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#3 olcowhand OFFLINE  

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Posted April 21, 2011 - 02:32 PM

The push pins rides against a lobe on the cam specific for the points pin. The lobe sometimes will wear a groove so far down that it can no longer move the pin far enough to push the points open. Only option then is to replace the camshaft, and if so, replace the push pin also. I have also seen the cams break in half. The cam is hollow & a pin goes through the hollow, so the cam can break & not fly all over inside.
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#4 FirefyterEmt OFFLINE  

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Posted April 21, 2011 - 05:59 PM

I don't know OCH.... With just the plunger, if a groove is worn down, I think that I would give JB-Weld a try. I mean, you may even be able to do that without a full tear down. I can't exactly remember how easy it was to get to on my JD motor. The plunger does not have all that much tension on it, so the JB may last a few years. Plus, it's almost free to try.
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#5 olcowhand OFFLINE  

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Posted April 21, 2011 - 06:55 PM

I would never try JB Weld on such an area myself, but might last a little while. Will be a mute point anyway if the cam is broken.

#6 FirefyterEmt OFFLINE  

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Posted April 21, 2011 - 07:18 PM

True... Not much to loose though! The cam in a pain in the rear on those too! That is where I am at with my K301... pulling it all apart so I can install the replacement valves.

#7 NUTNDUN OFFLINE  

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Posted April 21, 2011 - 07:31 PM

If it is just lobe wear for the pin, I would either weld the lobe and grind and polish smooth or find a replacement cam. I don't think JB would hold up for too long. Between the high heat, oil and how fast that cam spins there are a lot of wear factors involved. The other thing I would worry about is if the JB comes off of the cam then you have that floating around in the oil and could possibly mess something else up.
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#8 NUTNDUN OFFLINE  

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Posted April 21, 2011 - 07:32 PM

I would pop the head off and see if the valves are moving, going to have to do that anyway if you are replacing the cam. If the valves are not moving then you know something is broke other then just lobe wear.
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#9 olcowhand OFFLINE  

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Posted April 21, 2011 - 07:54 PM

When the cams break, it's usually between the valve lifter lobes, so only one valve would be moving. I've even seen them break at an angle to where the engine still runs fine, but this puts a load on the ends of the cam against the block & thrust washer. I wouldn't attempt welding it up, as the heat would affect the temper. Plus would be a bear to get absolutely smooth so as not to wear the pin down prematurely. Just too much work to take apart not to install a good unmolested cam....IMO.
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#10 PullingTractor OFFLINE  

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Posted April 09, 2012 - 09:22 PM

How to Fix the Problem with a Worn Points Lobe on the Camshaft -

Sometimes the point lobe on a single cylinder Kohler camshaft will get worn so badly that the timing can't be advanced enough to get adequate power out of an engine. There's a way to fix this, and there's no need to purchase a new high-dollar camshaft or do any welding on the old one. To fix a worn point lobe...

The entire engine must be completely disassembled and everything inside the crankcase removed.
Acquire a hardened 10-24 NC or 10-32 NF (thread size) x 3/8" (wrench size) hex nut.
Cut very short threads perpendicular on one end of the pushrod. To maintain correct pushrod length, cut the length of the threads the same thickness of the nut.
Secure the nut onto the rod. The nut is threaded onto the pushrod and jammed where the threads end. Loctite can be applied, if you choose to do so.
The minimum length of the Kohler 10-16hp flatheads and 18hp OHV engines points pushrod is 1.500" and the maximum length is 1.600". And the minimum length of the Kohler 7hp and 8hp engines points pushrod is 1.250" and the maximum length is 1.260". If it's too long, the points' contacts won't touch and the rod will need to be shortened. But if it's too short, the contacts won't open enough or at all and the rod will have to be replaced with a longer one. So measure accurately before (re)installing! The minimum diameter of each pushrod is .184".
On the 7hp and 8hp Kohler engines, the nut will need to be reduced in diameter (in a small metal lathe), and the inside of the block will need to be ground away for clearance of the nut.
This can also be done for an unworn lobe, to keep it from wearing later.
Remember that the pushrod must be inserted from inside the block before the camshaft is reinstalled!
By doing this, the nut will make contact with the outer unworn parts of the lobe, allowing full adjustment of the timing as if the lobe wasn't worn at all. http://gardentractor...ges/pushrod.jpg

#11 lyall OFFLINE  

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Posted April 10, 2012 - 09:40 PM

you can also use the head of the bolt too and cut the threads off
the bolt will turn, so the head of the bolt should be ground smooth or the points will jump.from the .020 setting and will act like it is out of timing

I have checked several my K301s and they are aluminum not steel, so the aluminum wears down install of the camshaft.

#12 GTTinkerer OFFLINE  

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Posted April 10, 2012 - 09:46 PM

Have you checked to see if the points adjustment hasn't came loose and moved to the point that the push rod simply can't travel far enough to push the points open? Easier and cheaper than pulling the engine apart.

Bill

Edited by GTTinkerer, April 10, 2012 - 09:47 PM.