BJS
Full Access Member
Ford Forgotton,
The carbon buildup is basically on the tip where it protrudes into the cylinder. The tip has a thick enough carbon buildup on it that you cannot easily pull the glow plug out of the cylinder. You can unscrew it and then to get more force to pull it out attach pliers and it's easy to see how they get broken. I have heard of one where the plug broke off when attempting to loosen the plug.
The carbon buildup is basically on the tip where it protrudes into the cylinder. The tip has a thick enough carbon buildup on it that you cannot easily pull the glow plug out of the cylinder. You can unscrew it and then to get more force to pull it out attach pliers and it's easy to see how they get broken. I have heard of one where the plug broke off when attempting to loosen the plug.