Home> Continental & Lycoming TroubleShoot
Black deposits on Champion spark plugs gasket
1. Leakage of combustion gas past spark plug threads. Most likely caused
by insufficient torque applied to spark plug.
Torque is one of the most critical aspects of spark plug installation. Torque
directly affects the spark plugs' ability to transfer heat out of the combustion
chamber. A spark plug that is under-torqued will not be fully seated on the
cylinder head, hence heat transfer will be slowed. This will tend to elevate
combustion chamber temperatures to unsafe levels, and pre-ignition and
detonation will usually follow. Serious engine damage is not far behind.
An over-torqued spark plug can suffer from severe stress to the Metal Shell
which in turn can distort the spark plug's inner gas seals or even cause a
hairline fracture to the spark plug's insulator...in either case, heat transfer
can again be slowed and the above mentioned conditions can occur.
| 
