It sounds like this http://www.radioles.com/works/kohler-21hp-single.mp3
I thought it might be something knocking NOT associated with combustion, so I disconnected the plug and turned the motor over for a while and it sounded smooth and OK. Just starter and normal air movement sounds. Is it valve knock from combustion?
I usually fix Briggs and Tecumseh, and this motor is my Dad's best friend's, so I'm trying to move a little cautiously and hoped to hear the voice of experience here before I go tearing into it. Thanks. Joe.
Unfortunately, I think It is replace time! The Courages we have had are blown or cracked block. I am uncertain of these parts, but not good either way! The metal has been wearing other parts in engine as it ran.
Red, I don't think that's what it is. I have yet to yank the oil pump, but when I look at the base of the cam shaft i see the triangular oil pump cover and it looks intact. Here's the assembly diagram. The only thing flat and sheet metal like is C? http://www.radioles.com/works/sm_20_690_01pg66.pdf
That rubber tube that moves oil to the head got HOT. I had the same thing happen when the counter balance went out on mine. It's a shame you can't buy anything but a short block for these engines. In my case I could have just cleaned the shaft and installed a new sleeve into the counter balance. (or even a new counter balance half) I bet if you move the counter balance around you will notice a lot of slop in it.
I took these pieces up to a buddy and he said it's plastic!? I'm betting my Dad's best friend, the owner, dropped the top of an oil bottle in the crank case. It got hot and was also pushed between some rotating parts and smeared into what we see now. Those pieces went whipping around and chewed up the rubber oil return line from the head.
Now, as far as I can tell, everything looks OK. I tried to wiggle the rod around and could not. I measured the side clearance and it is well within spec.
So, my plan is to un-mount the motor from the frame. Look at the oil pump. Then spray out the crank with water to get all the smaller bits out. Blow it out with air, then kerosene rinse with a new oil filter and see if it runs quietly. Does that sound, reasonable or should I disassemble the crankshaft/counter weights, even though it all looks good?
Thanks, as always. Joe.
Kencam, I see the galling on yours. Was this enough to make a loud knock? Uggh, well you answered my last question. I should go on with the tear down and have a look....
Is that metal pieces all over the bottom? Can't tell.
Yes, the sleeve on the bottom counter balance was grinding on the shaft. There was quite a bit of metal everywhere. The knock was from the slop in the counterbalance. Are there no metal shavings in yours?
In that case, I take back what I said. Check the valves and the cams. One of the cams has a centrifugal lever that occasionally causes issues. Did you pull the valve cover? If so was there plastic in there?
No. I haven't looked at the top end, yet. There is a tiny bit of play at the counter weights and crankshaft eccentrics. And, I mean tiny. Like if I pull side to side on the crank some oil pushes out from between the land and journal, but no real clearance to speak of.
I've decided to remove the crank though and really inspect it so I have no doubts before I move on to the top end.