1999 Ranger V6 3.0, spark plug failure

[eagles994X4]

Had a spark plug pop right out of the thread this morning. Has anyone had this problem? Is this just a bad plug? or, do I need to be concerned that it could be something major? Any help is definitley appreciated.

 

[SixFoFalcon]

With millions of 3.0L Vulcans running around out there for the past 20+ years, this is the first I'm hearing of a spark plug being ejected. While I'm sure it has happened before, it certainly isn't something this particular engine is known for. Perhaps the plug was cross-threaded or over-torqued, damaging the threads? Or perhaps some liquid was introduced to that particular cylinder? (Even a couple tablespoons of liquid is enough to create extremely high pressures within the combustion chamber.)

I guess look for evidence of coolant, excessive fuel, or oil inside the cylinder if you can.

 

[eagles994X4]

Thanks for the quick response Sixfofalcon.
No liquid at all. The plug did not come out completely. I had to remove the threaded section of the plug from the engine, the other half was still in the plug wire.

 

[eagles994X4]

Thanks jsgeorge4x4,
That is what I thought, but was not sure. It was a copper Bosch Super plus plug. So I put in a regular Autolite to replace it.

 

[SixFoFalcon]

Yup, that sounds like a defective plug to me. Can't say that I'm surprised it was a Bosch. <puts on flame suit>