Need Guidence - Kohler CH23S
 

Did some swapping with a friend and I now own his 2007 Cub GT2554. It is powered by the Kohler Command CH23 which has an issue. He was cutting grass and said there was a loud bag and the engine quit. It would restart but not running right, so he parked it and went out and got something new.

I just got it home yesterday and I only had a short time to play with it but this is what I know so if someone can point me to the next step, thank you:

1. The engine, although dirty, shows no outward signs of damage.
2. The engine turns freely, no binding or clanking.
3. Took the plugs out, cruddy with carbon but not oily.
4. Cranked the engine and finger test in plug holes seemed like good and equal compression.
5. Checked for spark, both sides seemed ok.
6. Put some good plugs in and started it. Got hellacious cracking exhaust sound.
7. Took the air cleaner off, found oil residue on inside of filter.
8. Tried another restart and sounded like machine gun coming out of carb.
9. Quickley shut 'er down and this is where I sit.

I don't think this engine has any internal damage and I feel that this is an ignition or timing issue. I've not worked on any Commands before that had problems, does my description sound like something common to them? Do they have a key on the flywheel that could have sheared? What do I look for next?

Sounds like a valve issue, but know nothing about commands.:bigthink:

Do a compression test with a gauge first. Next pull the valve covers and take a look. I would not be surprised if the cooling fins are packed with crud and it got hot. BTDT. Grass screen for the blower also likes to plug on these. Pic is from a 2550

Maybe a magnet let go on the flywheel. That would explain the bang with no visible damage. I've got a 25 that has a severe gouge behind the flywheel. IDK
I'm just throwing out an idea

Check both exhaust valves to make sure they open. Just WAG in addition to the other suggestions.

All you guys, thanks so much! Here's what I found....
Did compression test both sides, right (passenger side) 165 p.s.i., left (driver) 155 p.s.i.

Pulled valve cover off right side and rockers and everything looked fine, cranked it and everything looked to operate as it should.

Pulled the valve cover off the left side and saw this....

The rocker bolt had loosened, nothing was bent or ruined. Put it all right and tightened things down, fired it up and it purred like a kitten. Took it 9 years to loosen, now as the new owner I have to wonder whats next.

Thanks again for all who gave input, I was ready to go wild goose chasing ignition problems. You guys are the greatest!

Glad that worked out. I'd still pull the engine out, remove the tins and give it a good cleaning. I can see some crud at the top of your pic.

Oh absolutely. It will get a good spic 'n spanning in the next few days. I just wanted to know what I was dealing with first.

Don't know if I'll be pulling the engine though, looks a little heavier than a K301. :biggrin2:

Looked up one for sale, shipping weight said 115LBS. I use an engine hoist.

That top end looks like it is dry of oil. Or is that just the picture?

Probably dry because the push rod is out of place. They get oil through the push rods.

You win on that one sir. Always good to start simple and you did, great score. I got a dually once for 1200 dollars that the guy was told needed an engine for 7 thousand dollars. Found and replaced a broken valve spring, 5 dollar fix. It's definitely these times that make up for the times when it doesn't go your way. :beerchug:

Actually, there was very little oil in there but the tractor had been sitting for over a month.
When I started it in my testing, it ran maybe only 15-20 seconds before I shut it off so not much oil could have circulated. I also think I may have dabbed around with a rag to see what I could see, that would have been before I took the picture. I don't think there's a problem.

I did remove all the tins and the flywheel screen (except for the main shroud) yesterday. Sam Mac nailed it on debris, the flywheel screen looked almost as bad as the one in his pic up above. Blew it all out with compressed air and things look pretty good. I think today I will spray it down with degreaser and hit it with the pressure washer.

Thank you. However the guy I swapped with got a real nice Toro/Wheelhorse, worth 5-6 hundred, for his Cub. So I was taking a gamble not knowing what was wrong with this engine. He is my buddy, so now I don't know whether to feel bad or what.

On the other hand, he bought one of those $11,000 "green" tractors to replace this Cub, so......
Naw, I don't feel THAAAT bad.

Not to rain on your parade in any way, keep an eye on the motor for a while.
It is possible the loose valve adjustment was not the problem, but a loose seat in the head was, that allowed the rocker to jump off the pushrod.
Like I said in post #2, I don't have any experience on those motors, but been around the block a time or two.
Just a FYI.:bigthink:

I'm with George on that. I hope the best for you but it seems like a strange thing. Also that George has been around the block a lot. :biggrin2:

If it dropped a valve seat it wouldn't have the compression it does.

I've heard of the lifters pumping up and bending the pushrods. Usually in cold conditions. The lifters are like what's in a small block Chevy.

Agreed,
but if the seat reset itself into the head, it is going to happen again thus my comment to keep an eye on it.
Only time will tell ( or pull the head/look see)
hoping the best and it was just a loose stud nut.:beerchug:

Seen a lot of weird pushrod problems on them SBC's going back to the first ones in 1955.
prolly the most used /longest running design in history.

WOW! Now my brain is spinning. So much to ponder. I'll be doing cleanup and fixing minor stuff for another week or so until I feel comfortable that this thing is where I want it and will have it ready to test run, but you guys help a bunch for dealing with whatever comes next.

Thank ya'all!

I had the same thing happen to my CH 23 in my 1872. On mine the rocker arm pivot bolt loosened up and the rocker arm twisted to the side bending the pushrod and knocking a valve keeper out. I found it lying beside the valve spring. I installed a new pushrod replaced the keeper and cleaned the threads in the head and pivot bolt and installed them using blue loctite. I also did the same to the other pivot bolts to be safe. That was two years ago and it is still running great. I mow with it every week. I recommend the loctite treatment to insure that it does not happen again. The ch 23 is a good engine. If this fixes it you made a good deal. Good luck
Tom

Same thing happened to my CH-23 in a GT3204. Was my grass mower for 10 years. Same valve even. Replaced lifter and push rod. Re torqued all the rockers
On both sides. Have been using it as snowblower for last two years no more
Problems. Seems like a pattern.

I did not loctite anything at the time I discovered it. Nothing was damaged so I just corrected things and closed it up to see if it ran OK.

I have only used it 2-3 times since and everything remains fine. It is put away for the winter now but in the spring I think I will open it back up and do the loctite thing. Thanks for your inputs.