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:

 

[Diamondpilot]

I had a customer with a brand new Cub. When I mean new I mean new, maybe 1 hour of run time. Bought it in the Fall at TSC on clearance and when he fired it up to mow last spring same thing. It had us stumped. Anyway pulled the heads and there was a mouse nest in one cylinder. The little buggers had climbed up through the exhaust. Long story short the engine cost more than he paid for the mower on clearance to replace. Hope its not a similar issue.

What I am getting across is do not eliminate anything. You never know what you will find.

Chris

 

[Treemonkey1000]

You are certain it is the ignition module then before you go to all of that effort?. I was shooting for a bad spark plug myself. Believe me I have gone down the long road of troubleshooting to fix something that should have been an easy fix if I had been paying more attention.
Quick version of my story was an old Dodge police car I owned started back firing through the carb when you tried to start it.. After some quick checks I thought probably timing chain had slipped or something took off part of the timing chain cover which wasn't easy... Still backfiring. Took it to my Uncles shop. He fiddled for a couple of days and then woke up in the middle of the night with an idea. He pulled off the catalytic converter. Bingo that was it.. Stupid catalytic converters...
Have fun....

 

[jinman]

Just a thought. . . Have you tried premium gas? What about non-ethanol gas? I think your description might indicate the fuel is boiling and you are getting vapor lock issues after the engine gets hot. You could try to cool the carb float bowl with ice if you can get to it easily, but I think trying to get a higher grade of gas or gas without ethanol might improve the performance. Making sure all the air passages are clear is certainly also a good thing to do. Sometimes just dirt and grime can "insulate" the engine from the cooling air.

 

[captsomer]

The engine was pretty filthy. Lots of crud in the cooling fins. I broke out the pressure washer and cleaned everything while it was out. If the overheating thing was an issue, it shouldn't be anymore.

 

[banjodunn]

G'day while you have got it out i would be taking the coil and ign module down to your local kohler tech and get him to check them out they have testers that they plug straight into and can bench test them for you.


Jon

 

[Ken Cunningham]

I hope you checked the plugs before going thru all that trouble. I had a tiller once upon a time that would run great until it got hot then quit. Turned out to be a bum plug.

 

[2manyrocks]

I wonder how they can really bench these these ignition modules if the symptom doesn't show itself until the engine has gotten hot?

I've got a Kohler Magnum that is cutting out when the engine gets hot, and I'm suspicious of the ignition module, also. But I hate to put one on if it's not the real problem.

 

[Treemonkey1000]

I am with 2manyrocks when it comes to testing the modules or coils outside of the unit unless it is really hosed up. Intermittent problems are a bugger unless the unit is good and warmed up sometimes.

 

[jpinca]

The ignition seems pretty straightforward. I would swap the coils and corresponding plugs left to right and see if the miss follows the ignition or stays with the cylinder. If it following the ignition, then a new plug followed by a new coil are the solution.

If you had some old automotive ignition wires, you could do the same without tearing anything apart as a quick check, i.e. jumping across the cylinders.

JP

 

[ChuckinNH]

Long ago, and far away, my brother had a 383 Barracuda (yea, wouln't we like to have that today) It ran just fine until you pushed it a bit, and then it would break down. Chased it around the place, and finally found out it was the ignition wires leaking voltage when they got hot, or the engine was really cranking........ not that he ever did that.