Knock at Idle

[GTSRider]

My 580 hr. 2003 Kohler 20hp V-Twin has a knock at idle.
I hear it when I am done mowing, and waiting for her to idle down... so shut down will be ok.
It still runs on, even after idling for 3 minutes or so.
Should I run mid grade fuel in it ?
At full throttle and mowing through heavy grass tonight...
it does not Knock , and runs very smooth.
Is this a rod bearing... or something else.
Pete

 

[Sam Mac]

For whatever it's worth, I run Shell 93 in my small engines biggest reason is in this area it has no ethanol. I'd do an oil change and cut the filter open to see if you have metal in it. If you do you have something going bad. I also use a NAPA 1348 oil filter, it's for a Toyota, cost's less and it's larger with the same filtration specs.

 

[GTSRider]

Hi Sam ...thanks for the oil filter tip... and the octane.
I had 2 guys listen to it today... and they said it sounded normal to them...
I don't know... I am a motorcycle nut.... so I know that a motorcycle engine, and a Kohler V-twin engine, at idle will have different sounds...
maybe I am imagining a knock....

 

[mowcub]

It still runs on, even after idling for 3 minutes or so.

It's best to shut it down at a faster rpm and it will not have "run on". It's not good to let an engine diesel after shut down.

 

[JTKub]

It's best to shut it down at a faster rpm and it will not have "run on". It's not good to let an engine diesel after shut down.

Exactly- and that's the book way per Cub on how to shut down the engine. Either have it throttled up at s/d or quickly blip the throttle up after you kill the ignition. Letting the engine diesel can bend rods, spit valves, etc.

Joel

 

[Leo Rabon]

Ditto on the throttle up for shutdown. I run mine half throttle for shutdown and no problems. I also run 93 octane (100% gas) in mine since 93 octane is all that is available for me in 100% gas. The 87 octane is not the problem.

Leo

 

[savageactor7]

My 580 hr. 2003 Kohler 20hp V-Twin has a knock at idle.

A knock could indicate the electric PTO is on its last leg. To check it out next time you hear it while at idle and the PTO is off...loosen up the belt tightening rod and listen if the knock goes away.

Like you I also idle down for about 15 seconds but choke the engine off. No post ignition or bangs.

 

[GTSRider]

This 3000 series has a vacuum PTO.... I just put in a new
PTO idler wheel for the twin PTO belts.... so I don't know where the
noise is coming from.... I guess I'll just continue to run this tractor till
the end, and then decide if I want to go with a new online Kohler engine
at current price of $1,600.
Strange thing is this engine runs strong and like a turbine at full throttle when mowing. Last fall I did some major work ...done out doors through rain , sleet and snow... both crank seals, and both head gaskets...new carb.
Not a fun job,,,, when governor shaft fell into crankcase , and I had to open crank case to fix that.....took me over a month.
Thanks to all you guys for the shut down tips.... I never heard that before...
for some reason I thought the proper way was to idle down....
but now I see there is a better way.
Pete

 

[Sam Mac]

You can also pull the choke on just as you shut it off to stop the run on.

 

[savageactor7]

Oh it's a 3000...sorry I missed that.

Well if it were me I'd keep running it until it goes and who know's, it could run for a very long time and serve you well. It's certainly worth rebuilding ...at the end of the day it would cost you 6k+ to be on a machine like that.

I once knew a wrench that would use a wooden hammer to feel around an engine and diagnose problems. Perhaps that may be productive for you as well? Good luck and keep us posted.

...just say'en I use shell rotela 15-40.