Subscribe to a magazine

Thermal Overload

Back to article View Gallery
5 of 12
Problem: Thermal Overload
Matt Hallis, Product and Technical Support Manager at Bosch Corporation, says that this can be caused by using a plug that is too hot or by an overly lean air/fuel mixture (like a fuel management, intake manifold, or O2 sensor problem). Surprisingly, Hallis said that another cause can be insufficient spark-plug torque. Since one of the spark plug's duties is to conduct heat away from the combustion chamber, if a plug isn't tight it can't accomplish this goal.