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Cub K Series 12 Horse Smoking

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#1 toomanytoys84 OFFLINE  



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Posted April 20, 2014 - 07:38 PM

Pulled the 128 out to cut grass and started out running great. My yard has a couple small hills and when I went down and up it would start smoking bad. Then it was fine on the flats. Smoke down/up hill.

Oil level was spot on now it's a 1/2 quart low. Left a small spot of oil under the front like it's leaking out the output shaft.

I had a little smoke on start up last year maybe 2 seconds.

Anyone seen this? The only thing I can think of is blow by. Maybe getting positive crank case pressure.

I've never had an engine do this. I have another rebuilt 12 and a 16 to put in it but I don't want really as this is the factory engine. But it's early 70's and never been touched other than preventive stuff

Anything to check?

Edited by toomanytoys84, April 21, 2014 - 08:41 AM.

#2 JDBrian OFFLINE  


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Posted April 21, 2014 - 07:46 AM

I'm not sure what it could be but have you checked your crankcase breather. If it's plugged and you have even a little blowby it would force oil out through the weakest spot. If the breather is working normally any oil forced out by blowby should be coming from the vent tube. If those Kohlers get carboned up it can cause blowby. You could try sea foam or pull the head and have a look. I hope it's something simple. A half a quart of oil in one mowing session is a serious problem that you need to get to the bottom of before it does some major damage. 

  • toomanytoys84 said thank you

#3 toomanytoys84 OFFLINE  



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Posted April 21, 2014 - 08:44 AM

I'll check the breather.  I don't have a lot of time these days to work on stuff.  That gives me something I can check without a lot of trouble.


If the breather is ok I'll pull the head.  But I better find a gasket set before that.  I am figuring its due for a rebuild.  I have 2 nice engines that I can drop it that are rebuilt.  I'd just need to reuse the carb fly wheel and blower/tin work/starter to finish it off.  But I hate to change it. 


What confused me is I have never had an engine smoke only on a hill, which would normally lead me to believe the oil level is too high, but it was just a touch below the full mark.

As far as I know this motor has never been opened up since it was new.  We have had this tractor since the early 90s.  The original owner bought it brand new.  So it has MANY MANY hours on it.