K301s knocking problem after rebuild........?


Old 07-11-06, 02:05 AM
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Join Date: Mar 2006
Posts: 39
K301s knocking problem after rebuild........?

Everything has been taken apart, cleaned, new piston/rings installed, new valves installed, and everything is torqued to spec's....... Still, I have an ever-so-slight knock. When the new valves were installed, I couldn't get the proper clearance from the valve tappets to the valve stem on the exhaust side. Can this possibly be the reason for the knock? Should I remove the valve, grind the valve stem a bit and re-install or will this cause premature engine failure if I put it in service anyhow. Like I said, It is an ever so slight knock. You really have to pay close attention to notice it. The motor starts and runs perfectly. Better than it ever has. Thanks for any and all shared info..........ALAN
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Old 07-11-06, 11:49 AM
bontai Joe's Avatar
Join Date: Apr 2004
Location: Pennsylvania
Posts: 592
You mentioned a new piston and rings, did you have the block bored and then use over size parts? Or just replace the old std piston and rings with another std. piston and rings?
Old 07-11-06, 02:46 PM
puey61's Avatar
Join Date: Apr 2004
Location: Upstate New York
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I'd be concerned with the rod to crank clearance. Did you spec them out to be sure you are within tolerances? As for the valve clearance issue, what, specifically, are the clearances you wound up at with each valve? You stated "knock" and if it were valve noise you likely would have described the noise as a ping or tapping sound, not a knock. If you had excessive clearance at the exhaust valve you may hear a knock but the clearance would have to be pretty great to get this.
Old 07-12-06, 08:01 AM
bontai Joe's Avatar
Join Date: Apr 2004
Location: Pennsylvania
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I'm thinking that if it wasn't rebored, he night have an "egg" shaped cylinder towards the bottom of the cylinder, and he is hearing the piston slap as it "wobbles" up and down. It's kinda common on the "K" series Kohlers as they wear and it would be the faint kind of sound he describes. Of course if it was rebored enough to true up the cylinder wall all the way down, and the proper size piston & rings installed, then it's something else.
Old 07-12-06, 06:42 PM
Join Date: May 2006
Location: Iowa!!!!!
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Along the line that Puey is thinking did you tighten the rod cap nuts with a torque wrench? Those are easy to over tighten. They only spec at about ten pounds. If you happened to do something else, I don't believe I would put it into service until the rod to crank had been checked.

If you over torqued them you could have pulled the rod bolt threads out of the aluminum rod. If this was the case it would all fly apart shortly.

Hope this helps
Old 07-12-06, 08:37 PM
mikesmalleng's Avatar
Join Date: Jun 2006
Posts: 109
Most K series Kohlers including K301S (10hp) have steel cylinders which I`ve never seen wear out-of-round. They do have crankshaft bearings that could cause a knock if worn.
What was the purpose of the overhaul in the first place. You did`nt say that you replaced the rod. is the rod or the crankshaft journal marked or scuffed up?

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