Kohler EFI Head Replacement Turned Into a Bigger Problem

Parts and tools used in this video: • Kohler EFI cylinder head kit (Part # 24-818-03-S) • Cinematic oil suction device • Spanner wrench (Part # 34-305) • Lucas assembly lube • Anti-seize and dielectric grease The diagnostic journey starts with addressing a loud popping noise on a personal Kohler EFI mower engine with over 4,600 hours, caused by a seized and broken exhaust stud blowing out the exhaust gasket rather than a failed head gasket. The initial plan involves pulling the engine from the mower, tearing down the components, cleaning the surfaces, and installing a new un-assembled cylinder head kit, which requires assembling the components and lapping the valves before setting careful torque sequencing. While inside the engine, noticeable wear with excessive piston-to-cylinder wall play becomes apparent. Despite the age and wear, the project continues until a bolt snaps off in the opposite head. Multiple extraction methods—including welding a nut onto the broken bolt and applying heat—fail to remove the seized fastener. Realizing that the engine has reached the end of its practical lifespan, the decision is made to halt the repair and pivot to ordering a long block to get the mower back into operation. WHAT WE COVER IN THIS VIDEO: 0:00 Introduction to the mower and engine history 1:57 Unboxing the new cylinder head kit and draining engine oil 3:04 Disconnecting the PTO clutch and pulling the engine mounting bolts 7:45 Removing throttles, fuel lines, and extracting the engine 12:20 Dismantling the exhaust, fan cover, and engine shrouds 1:04:20 Removing the cylinder head and inspecting piston-to-cylinder wall wear 1:14:10 Lapping valves, cleaning components, and assembling the new head 1:33:00 Installing the new head gasket and torquing head bolts to the engine block 1:42:00 Installing push rods, rocker arms, and bleeding hydraulic lifters 2:06:00 Cleaning and reinstalling the intake manifold with proper torque sequencing 2:19:00 Reconnecting wiring harnesses, sensors, and throttle controls 2:32:00 Reinstalling the cooling fan and engine covers 2:41:00 Troubleshooting a snapped bolt and attempting extraction via welding 2:55:28 Final assessment, decision to order a long block, and wrap-up If you find this video helpful, consider liking the video, subscribing, and leaving a comment. It really helps support the channel and lets me know what equipment you’d like to see repaired next! #Kohler #SmallEngineRepair #EngineRebuild #LawnMowerRepair