Ok 86 f250 6.9 4 speed idi runs good got her to start without ether after installing my bran new motorcraft zd1 glow plugs

Po had 7 newer autolights in it and 1 old anyway the 1 old one took me 10 minutes to remove and it just seemed like it was stuck I put the new one in but it won't tighten all the way down like the rest of them is this really a problem as long as it's sealed?

 

Take a look at the one that came out and see if there is a piece of the old one missing. It might have a piece still stuck, and if you tried to tighten the new one down on the broken off piece, then yes, you would have a big problem. If it was mine, I would take a piece of stiff wire, like a coat hanger, and see if it went down easy all the way past where the old glow plug fit. It won't go too much farther in, because the glow plug fits into the precombustion cup in the head, but is should go in farther that the length of the glow plug.
Before I did any tightening on that plug, I would sure be looking to see why it didn't fit all the way in.
In fact, I would be questioning why the PO did all the glow plugs except that one. He might have cross-threaded that hole and just left the old one in.

 

Not sure why the po didn't change it other than he probably couldn't get the old one out it took me ten minutes for that one glowplug and I know the whole plug came out because I checked it ALOT of times I think maybe there is a bunch of buildup or something in the hole of the head for the glowplug tip and it's probably slightly cross threaded yesterday she fired without ether on glowplugs and this morning for some reason the ol girl just wouldn't do it I will look a little closer today after work but last night looking at it the bottom part of the threads in the head looked funny but the top looked fine?

 

$20 is all it will cost you for piece of mind. go to napa, order the 10mm1.00mm tap and get yourself flex magnet. needs to be small but they have ones that pick up a 10oz wrench. there pretty sweet! remove the injector, stick in the magnet, and tap the gp hole. it will collect anything that has fallen in, hell iv pulled gp tips out before in mine!

 

Thankfully it will be cheaper than that a buddy of mine has a $350 dollar snap on set and think it will work if I just hook a powerful magnet to the tap? To magnatize it?