I have a 92 ford explorer and about once a month I need to change one spark plug because it is broken but all the others are fine? What is wrong?
What would cause one spark plug to keep breaking?
Plug breaking? If the porcelain is breaking around the electrode, check for coolant leak in that cyl.
What would cause one spark plug to keep breaking?
Check the engine mounts. Sounds like one is broken (almost certain to be the left side) allowing the engine to torque over enough for the plug to hit something.
Maybe carbon has built up in that cylinder and is hitting the plug. I have seen plug damage due to worn bearings that allowed the piston to actually hit the plug. Try a shorter plug in that one cylinder as a test.
