solenoid parts and pieces

[gary noblit]

so many have never seen the inside of a solenoid so here goes...from bottom up : coil wire that gets energized by 12v from key switch: creates magnetism that pulls the center rod down,there is a spring on this rod to push it back up when energy is released(not in pic): the circular disc makes contact with both outside poles allowing current to flow from batt to starter,these contact areas get pitted to a point they don't connect anymore ..so a "click" may be heard because center rod moves but doesn't make" good" contact.I've never seen one meant to come apart to clean contact area.In the good old days we used two screwdrivers to jump the posts(mostly my old Ford) So ,nothing magical going on inside but very functional piece

 

[snicklas]

That arcing that causes the pitting/carbon build up is why some solenoids have a “rotator“ for that disk, so it makes contact in different places every time, instead of the same place every time it’s activated. I’ve read the Motorcraft solenoid used for the glow plugs on the 7.3 IDI Ford trucks are this way. The one in the starter circuit doesn’t….