Kohler Valves Sticking

[dunoon2]

Got a call for a Craftsman with a Kohler Command, will run for 30-45 min then quit, usually doesn't start right back. Will start after waiting 15-20 min. First thought ingiton coil. Replaced it. Haven't had a chance to check it out (raining) but, got thinking it might be valves sticking. Is there something that I can spray or put in the fuel that will unstick these valves? I really don't want to tear in to the head, if I can help it. Thanks for any suggestions.

Rich Davis
3M's
Mobile Mower Maintance.

[Mek-a-nik]

Check the gas cap vent?

[Luffydog]

check valve specs then compression test followed by a leak down test. pull valve covers off take plugs out roll engine over and inspect. i have been told by another tech he put a little seafoam in the oil and ran for a while and it cleared them up afterward he changed the oil and filter. personally i would have done a valve job like needed.

[Walt 2002]

IF the valves are actually sticking, use something such as Marvel Mystery Oil per instructions on container.

Walt Conner

[HondaG100]

I second the Marvel Mystery oil and Sea Foam ideas. I have seen valves stick from bad gas and these products fixed it. Not your issue though the way it sounds. Sticking valves stick when cold also in my experience.

[Arkie]

Check the gas cap vent?

Right about gas cap vent, and check or clean the fuel filters.

I would think about having a primer of gas handy to squirt in the carb when it quits to see if it will momentarily re-start on fuel and also have my ignition spark tester ready if no go on gas.

Very doubtful that its valves sticking when hot then un-sticking as it cools. Also doubt that it's valve lash because it quits when running. If you mean the engine shuts down rapidly with no hint of a erratic miss most likely not valves or valve lash. Sometimes a hint that it's fuel related is to immediately go to idle and apply full choke. If it attempts to keep running for awhile it might fuel starving related.

Let us know what you find?

[dunoon2]

The first thing I checked was the gas cap. When it quits it just like you turned off the key, no warning what so ever So thats why I thought it was the coil..

[bgsengine]

The first thing I checked was the gas cap. When it quits it just like you turned off the key, no warning what so ever So thats why I thought it was the coil..

Have you changed out the spark plugs, and also wiggle the key switch around, check safety switches (bad seat switch?) I'd do all of those before suspecting coil. I agree with the rest - I seriously doubt your problem is valves and they would not cause it to quit suddenly as you describe.

[Arkie]

The first thing I checked was the gas cap. When it quits it just like you turned off the key, no warning what so ever So thats why I thought it was the coil..

Have you changed out the spark plugs, and also wiggle the key switch around, check safety switches (bad seat switch?) I'd do all of those before suspecting coil. I agree with the rest - I seriously doubt your problem is valves and they would not cause it to quit suddenly as you describe.

Since it don't re-start for several minutes or until it cools off gives you time to test for problems.
In meantime I would also look at a wiring diagram or figure out how to do a temporary bypass the safety shutdown switches. (and keep a electrical tester close by ready to go) The key switch or a safety switch will kill the ignition and make it appear to be a bad coil and bypassing the ignition coil control circuits will isolate them so as the coil is only thing involved in the ignition.

You might also check the ignition fire now while the engine is starting and running cold so as to get a comparison when the engine stops. A weak fire will sometimes start a cold engine but won't start a warm or hot engine. and this is easily overlooked as appearing a engine has good fire when in reality it has weak ignition fire.