Kohler CV15S - Rod Knocking or Something Else?

[Silverleaf]

I currently mow about 2 acres with a 42" Scotts mower powered by a Kohler CV15S. It's been well maintained and has been running fine. Yesterday, just as I was finishing up, the mower quit running. I expected that I was out of gas , as I had been mowing for a few hours, but the tank still had plenty of fuel left. I went to restart, and it fired right up.....but with a loud "clanking" sound. I quickly shut it down, and decided to let it cool, while I went to trim. Restarted later, and the loud clanking is still there.

I haven't had much time to dig into it (had a storm come through and downed a tree across my driveway), but here is what i know:

• Engine has been running fine up to this point, no hint of trouble
• Oil level is fine; oil is clean
• Pulleys on the underside are tight. Had them come lose before, and it makes quite a lot of noise as well

Here is a quick video recording from my phone, although the "clanking" sound seems to be much more noticeable in person.




So, what do you think? Is this a knocking rod or possibly something else?

 

[Fish]

Don't run it anymore.
If it throws a rod, you won't have anything left to fix.
What kind/viscosity oil have you been using?
Where in Ky. are you?

 

[Silverleaf]

10w30 through a Purolator One filter.

East central KY, near Mt. Vernon.

 

[okiepc]

I agree, don't run it until you diagnose it, sounds more to me like a push rod.

 

[Fish]

On these engines I have seen the carb's throttle plate screws fall out and get sucked into the engine, yours kind of sounds like that. The screw would be imbedded in the top of the piston if that was the case.

 

[Silverleaf]

On these engines I have seen the carb's throttle plate screws fall out and get sucked into the engine, yours kind of sounds like that. The screw would be imbedded in the top of the piston if that was the case.

Thanks.

I pulled the valve cover and I did'n't see any red flags. Rotating the engine by hand, everything seems to work as it's supposed to.



I haven't pulled the head yet, but it does look like one of the small screws that holds the carb butterfly on is missing. (click on the image to get to a full size version and you can see it better).



What kind of damage is that little set screw likely to have caused to make this thing clang so loud?

 

[Fish]

Just pull the head and pluck the remains of that little booger out, and reassemble, and Loctite all of the carb screws.

 

[Silverleaf]

Well, I messed up. Got in a hurry and rounded off the corners of one off the head bolts. So, the head is not coming off without a lot of work.
I may just put it back together and hope for the best.

 

[Fish]

To be honest, it will probably pound on in or break apart. The only serious loose screw failure was on an old Tecumseh OHV.

He heard a loud whack, and it shut down 10 foot later.

When the piston hit the screw, the rod cracked up and shattered shortly thereafter. Put a new rod in, he was good to go.

The only real danger is if the screw is near the edge, and it might be a bigger problem.

But you definitely need to locktite in your carb screws.

 

[DaveTN]

Just wondering if this engine has counter-balance gears or weights that might be clanging around? I worked on an old Kohler 14 HP side shaft cast iron engine that had 2 counter-balance gears in it. Found some teeth in the oil drain pipe! That means the counter-balance gear is jumping up and down and could possibly lock up the engine and destroy it should more loose teeth get wedged in something. It would run, but clang like a mule kicking in a metal stall. It's been shut down for now and repairs delayed for a winter shop project .