Intermittent Kohler Problem

[captsomer]

Hello All,

I have a Kohler that is giving me problems. Its a CH22 twin cylinder horizontal shaft engine mounted in a Cub Cadet tractor with about 500 hours on it. It starts fine. After a few minutes of running it gets real weak. Just turning on the belly mower or aggressively climbing a steep hill bogs it down bad and almost kills it.

I suspected that it was only running on one cylinder so I put it away in the garage to be looked at later. The next day I tested the spark at both cylinders. Tested fine. I checked compression and both cylinders also checked fine. Just for kicks, I checked the fuel supply. The hose coming out of the pump was running very strong. I gave the carb a quick cleaning and put it back on. I put it all back together and started to mow a little grass. It was running fine up until about ten minutes into it when it started to get weak again. I quick limped back to the garage and checked spark and compression. Both were fine.

This time, I removed all of the front engine shrouds and heat shields along with the entire exhaust system. I fired up the engine and it ran fine (loud but fine). I felt with my hand, that the exhaust from each cylinder was hitting very strong signifying that each was firing strong. I took of mowing grass with the loud engine. This time, about five minutes into it, it started running weak and I could feel / hear that the left side cylinder had stopped hitting. Once in a while it would hit a couple of times, but for the most part, it was freeloading and not running.

I removed the valve cover and pushed on the valves and they seemed ok.

I'm stumped. I think its either a valve that gets hung up once the engine warms up or a bad spark that gets lazy when it gets hot.

Does anyone have any experience like this? Which direction should I go? Advise?

 

[Treemonkey1000]

You might try swapping plugs for one. Next make sure your oil is up to level. Is the oil filter ok. I know that oil should be the same for both cylinders but if one oil passage is not as clear as the other.. When the unit heats up you may be losing compression in that cylinder. I would contact the dealer and ask about any 50/100 hour or more maintenance. I wouldn't run it too much more until you get a better idea of what is going on.
I thought maybe your hydraulics or drive belt might have been causing it to bog down and making it seem weak. But you found the left cylinder acting up so that eliminates that scenario.
I have a 25 Hp Kohler twin for my Chipper and it is a beast. Still make sure your oil is up to level. Check your tractor hydraulic fluid level and filters just as a precaution

 

[Just Bill]

You might try loosening your gas cap to check if your vent is plugged.
It could be a number of things but it sounds like its starving for fuel.

 

[banjodunn]

G'day i would be getting your local kohler guys to check the ign it sounds to me like is is an ign fault as it warms up.


Jon

 

[oldnslo]

Can you do a compression test when it is hot? Possible one of the valves is to tight and when it gets warm the valve is being held open causing you to loose compression on that cylinder.

Can you check the valve clearances when cold at TDC. Not sure exactly what they should be but would guess around .008 - .010 for the intake and .010 - .012 for exhaust.

Roy

 

[Kernopelli]

Sounds like you've done a good job eliminating things but since this occurs after the engine runs for a time I would guess either ignition coil or valves . If you suspect a valve is sticking, a quick shot of ether will sometimes cool it enough to temporarily free it. oldnslo gives some good info for adjustment.

My first guess would be the same as banjodunn's though... a weak coil. Your symptoms are very typical, it gets hot and quits firing. I don't know if your engine uses the Smart Spark pack or "regular" coil but I was originally told the smart spark packs were "very expensive" ( hundreds$$$ each) for my CH20 but I recently saw them on Tulsa Engine Warehouse's site for about $60.

I have also found the guys over at Lawnsite.com's mechanical forum to be extremely helpful at times. There are several factory authorized Kohler mechanics that are on the site almost daily that are very knowledgeable and helpful....much like many of the guys here on TBN :thumbsup:

 

[captsomer]

Thanks for the input guys. I'm going to chat with my local repair shop today. I'll keep you posted.

 

[Kernopelli]

Just remembered something, Kohler has online service manuals available for the CH line on their website. They are fairly comprehensive and may be of help. I even copied it to a DVD ( it was too large for a CD) to keep on hand.

 

[captsomer]

Yeah, I found that manual on their site. Its very well done and packs a lot of info.

 

[captsomer]

HOLY CRAP! You have to remove the entire engine from the tractor to replace and set the coil! I'm gonna need another day or so to let you know how this goes. I got the engine out last night. I may finish tonight....:confused2: