My Kohler won't stay running!
 

My CH20 Kohler in my 2518-48 has ran perfect for the last 11 years or so. This last weekend it wouldn't start and stay running (backfiring through the carb). It would only run with the starter still engaged and its drowning in gas. The spark plug on the left is blacker than coal all full of soot. The one on the right looks fine. I had access to another carburetor and that is not the issue. Why is it getting so much gas and why is just the one spark plug fowling?

Thanks in advance.

Bob

I would suggest looking at your VALVES.

I didn't think to place my finger over the left spark plug hole to see if there was compression. I'll try that tonight when I get home. I'm confused about all the gas. Is that normal with valve issues? Seems like the fuel pump is on steroids.

Bob

sounds like a compression or spark issue,your engine has 2 coils one for each cyl.

Pull the head. It either dropped an exhaust valve seat, or blew the head gasket. Or both.

If the cylinder is dead the gas going into it will not burn. As others said check the compression and ignition on that cylinder first

I seem to have good compression on both cylinders using the finger over the spark plug hole method. It will 'try' to run if I have the choke on. Soon as I begin to take the choke off it starts backfiring through the carb. It spits gas up through the narrow port on the back left side of the carb before it floods out. I remove both plugs and they're wet with gas.

Bob

I won't offer much help beyond don't use the "finger over spark plug hole" test method for compression unless you can read PSI with your finger. Rent a compression tester from Auto-zone, O'Reilly's, etc. and report back. It'll provide a LOT more info than "I seem to have good compression on both cylinders using the finger over the spark plug hole method.".

I have a1711 that was doing that it was the condenser:bigthink:

The CH20 that the OP is asking about doesn't have a condenser on it. :bash2:

Just my 2 cents but I'd check to see if you have spark on both plugs, if you do I'd be looking into the carb. I know you said that you tried a different carb but it's possible they both have problems. Only way I know that you have gas shooting out the top is a stuck needle or bad float.

I'll be mister obvious today. got gas in it?

That has happened to me more than once. It'll make you tear your hair out.

Maybe old gas that has turned to crap?

You are correct! It turned out to have a stuck exhaust valve on the right cylinder. The mechanic worked it free and ask me to try it for awhile. So far so good. I've done a few hours of mowing and it's been running like its old self so far.

The mechanic said the "right" cylinder. This has me stumped because the left plug (as you're sitting in the seat) was all black and fouled and the right plug looked fine (chocolate brown).

Which side is cylinder #1 and which side is cylinder #2 when you're sitting on the tractor facing north? My guess is #1 is on the left.

I see complete head assemblies for sale on ebay for some models reasonably priced. I wonder if that's a good option or is it better to rebuild the head?

Thanks for the help.

Bob

I'd like to rephrase my question. With the CH20S 64638 Kohler engine, is the valve cover that has the oil filler cap on it cylinder #1 or cylinder #2?

Anyone know?

Thank you,

Bob

If you paying someone to rebuild the head, it's probably just a cheap to buy new.

The cylinder furthest forward is always number one.

What does facing north when sitting on the tractor have anything to do with cylinder numbering? :bigthink:

I just finished viewing an exploded parts view/list and I now have the impression that the cylinder on the left side (viewed as you're seated on the tractor) is cylinder #2.

The 'facing north' thing was just to see if anyone was paying attention. I'm glad you caught that.

Bob

Does it matter? It's not like you need to know for any service reasons. If it had a distributor that would be another thing. Usually they are just referred to as "left" and "right". Remember though, the motor is in "backwards", so that gets confusing. :biggrin2: The rear main seal is the one behind the PTO.

Kohler didn't assign numbers to them. If I had to say, I'd say it would be the one without the oil fill. It's the closest to the "front" of the engine. Let it go, it's not important.

Yes, it does matter. The two heads are not interchangeable. They have different part numbers so you can order the one you need.

Kohler labels them as cylinder #1 and cylinder #2. They do not refer to them as left or right. You did hit on something interesting though.

The engine is in backwards.

That would make left right and vice versa. That is if Kohler referred to them in that fashion which they do not in my service manual.

I'm still thinking the head with the oil filler plug is cylinder #2 and the head with the plain valve cover is cylinder #1. Maybe someone who actually knows can chime in.

Bob

Mr. Bob, I do know what I am talking about. If you would take time to look up parts on any parts site or in a book it clearly shows which is which. Or just tell the guy on the other end of the parts counter you need the one with or without the oil fill. This is incredibly simple.

#20 is labeled as Cylinder #1 and #36 is labeled as cylinder #2. Which is exactly what I said. The one closest to the front is #1, which is the one without the oil fill. Outside of this picture right here, this is the ONLY time that cylinder number means anything. Service manual does not differentiate during any procedures.

Attachment 53225

Yes, the cylinders are numbered (whether it matters or not).

The thing that was throwing me a curve was the mechanic told me the right cylinder exhaust valve was stuck which he managed to get free without removing the head. When I pulled the spark plugs (prior to taking it to the mechanic) I found the left plug (as you're sitting on the tractor) was black and full of soot. The plug on the right side of the tractor was fine.

Because the engine is in backwards left becomes right and vice versa. I meant left side of the tractor, the mechanic meant right side of the engine. Same difference.

So please bear with me. I work in the electronics industry where many service manuals are deliberately written with encryptions.

Thank you, J-Mech, I do appreciate it.

Bob

I've ran my Cub for about 6 hours since the stuck valve incident and it's been running stronger than ever before. However, I left the new carburetor (that was not the problem) "on" since I was unable to return it. I pulled my plugs after the six hours and they're looking fairly white. They use to be a nice chocolate brown in the past. The new carburetor is exactly the same as the old one (same Keihn part number exactly).

Should I be concerned about this? Maybe go to the next heat range down? I've been using Champion RC12YC from day one.

What say someone?

You may want to richen up the low speed fuel a bit with the adjustment screw. If you need a copy of the service manual pm me with your e-mail address.

Thank you Sam Mac, I'll back it out a tad and see what happens.