Kohler engine Blown Plug

[MikeC]

I have a 14 HP Kohler K series engine that blows the spark plug out of the hole. I removed the head, had a helicoil installed, and reassembled with a new head gasket. Same thing happened. Anyone have any idea what is causing the plug to blow out? TIA Mike

 

[El Toro]

Are you sure the heli coil was installed correctly? I had one on a B&S installed several years ago doing the same thing until I had a heli coil installed. You may need to go to a Keensert.
Hal

 

[RobMD]

I have no idea what would cause a plug to blow out in the first place. My only guess is stripped out plug hole from overtightening/crossthreading.

 

[bradley martin]

I had the same problem w/ a l2 hp Kohler and ended up replacing the head...I believe the threads are a weak spot in the aluminum head.

 

[buickanddeere]

Possibly high combustion chamber pressure and shock waves from detonation,or.........
Use a 3/8 torque wrench set to inch lbs when installing the plugs. Its amazing how little torque is required.
Is the engine running hot with a lean mixture and 87 octane in the tank? The cooling fan/fins maybe anything from oily/dirty to plugged.
For the few cents difference on small aircooled engines. I run premium in the chainsaw, snowmobile etc. Detonation/knock is what ruins pistons/cylinder walls in these engines instead of lubrication failure.