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JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1140
Experience:  Owner/Service Technician at S & J Small Engines
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I have an overheating problem with a Kohler Command Pro 25Hp

Customer Question

I have an overheating problem with a Kohler Command Pro 25Hp engine. Model #CH742. Spec # ***** Serial #4400802861. Muffler was running at about 800F. Tach has rpm's on both cylinders at 3400-3500. Oil is topped off. Took muffler off leaving exhaust pipes on engine and found the longer pipe registered about 500F while the shorter pipe (from cylinder nearest the muffler) read close to 800F. Any thoughts? Chris
Submitted: 2 years ago.
Category: Small Engine
Customer: replied 2 years ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  JohnF2015 replied 2 years ago.

Hi, my name is***** will be assisting you.

Does the engine seem to have good power still? Have you noticed any backfiring?

Customer: replied 2 years ago.
John, there has been no backfiring at all. The last two times I used the chipper (which is what the Kohler engine is powering) I did have an issue with the choke control. I would quickly loose power with the choke open after initial start-up and have to close it almost all the way to get enough power to drive the cutting disk. Then after a while I could open the choke and finish the job, but everything seemed way too hot. Now this morning, when I was troubleshooting the engine, it ran fine with the choke wide open. But then again I only ran it for 5 minutes or so. In that time the temp rose to the 800F and I shut it down. Again, one cylinder was 800F, the other only about 500F or so. Also checked compression - both cylinders measured the same - about 175lbs. Spark plugs looked the same as far as I could tell. Must note that this is a brand new engine and I can't have more than 25 hours on this. I got it last November and it was running fine up till the last time i used it in June. Then it crapped out on me two Fridays ago.
Expert:  JohnF2015 replied 2 years ago.

It sounds like the engine is starving for fuel which would cause it too run hotter than normal. You may have the carburetor jet partially stopped up causing this, that would explain having to run partial choke and the heat. On a new machine I would normally recommend having it looked at by your local dealer but chances are they will give you a hard time about warranty if this is a fuel or carburetor issue since Kohler will most likely not cover it under warranty.

Maybe try running a fuel system cleaner through it, something like Sea Foam. Otherwise you will end up having to take the carburetor apart and give it a good cleaning.