Small Engines (Lawn Mowers, etc.)/Kohler engine


Kohler Command 15; Family: SKH426U1G2RB; Model #: CV15S; Spec #: 41540; Displ CC: 426; Serial #: 2534014123
This engine is getting gasoline in the oil crankcase. What do you think is the cause and how do I fix it?
Tim McCarter

Most likely the inlet needle or inlet needle seat is leaking.  The most common solution it to remove, dis-assemble, and clean the carb with compressed air from an air compressor.  Some spray can carb cleaner can help during the cleaning process.

With a clean carb, replace any wore parts...usually the bowel o-ring/gasket and the inlet needle and/or inlet needle seat.

You can verify the inlet needle is sealing by using a pressure tool.  The carb should maintain (hold) about 4-7 PSI.  Here is the tool I use to check the condition of the needle/seat:

If you are not familiar with small engine carbs you can find lots of videos on You Tube; search for Kohler carburetor, rebuild or mower, lawn mower or small engine carburetor cleaning...just search some key words and you will find a lot of videos.

Have you ever rebuild a carb?  Do you have an air compressor?

Let me know.

Small Engines (Lawn Mowers, etc.)

All Answers

Answers by Expert:

Ask Experts


Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

©2016 All rights reserved.