What can cause cracked coils?
Modern ignition systems operate with high primary ignition current levels, typically between 6 to 10 amps. This high current is required to produce the secondary ignition energy to meet modern engine demands. Current flow at this level will generate a great deal of heat, the modern ignition coil is designed to be able to withstand this providing it is correctly applied and not exposed to abnormal environmental conditions. It is important to note that when replacing an ignition coil, the correct specification coil is used for the application. Incorrect specification may result in abnormally high coil current resulting in the overheating of the ignition coil and consequential cracking. Other defects may also occur including damage to the ignition module or power transistor unit. Note that measurement of the primary and secondary coil resistances only are not a reliable guide for coil selection, always use the manufacturers recommended application data.
