Rodeo S 2WD L4-2.2L (1999)
A broken or cracked lower insulator tip (around the center electrode) may result from damage during re-gapping or from "heat shock" (spark plug
suddenly operating too hot).
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Damage during re-gapping can happen it the gapping tool is pushed against the center electrode or the insulator around it, causing the insulator to
crack. When re-gapping a spark plug, make the adjustment bending only the ground side terminal, keeping the tool clear of other parts.
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"Heat shock" breakage in the lower insulator tip generally occurs during several engine operating conditions (high speeds or heavy loading) and
may be caused by over-advanced timing or low grade fuels. Heat shock refers to a rapid increase in the tip temperature that causes the insulator
material to crack.
Spark plugs with less than the recommended amount of service can sometimes be cleaned and re-gapped, then returned to service. However, if there is
any doubt about the serviceability of a spark plug, replace it. Spark plugs with cracked or broken insulators should always be replaced.
