hopp wrote:
The deep socket is really thin being 1/4" drive and seats well over the hex portion.
Well that one is ruled out then.
I bet one of the previous owners twisted apart #1 and just left it in the hole. That's as good a guess as any.
This, I suppose is where I'll offer my very limited experience, as I am by no means an expert on broken glow plugs. I have, however come across a dozen or so. I will be referring to the photos below.
The examples of this type that I've ever dealt with, were always separated between the hex, and the threads. Beyond that, they were without exception separated directly below the hex secton, and above the round body section located between the hex and the threads. (I hope that makes more sense than my previous description.) Between the tip, and the round body section is the tapered seal. Similar to 1960s Ford spark plugs, this seals between the combustion side, and the atmospheric section of the plug. The round body section between the threads and the seal is the only part with compressive pressure, and this compression is how torquing the plugs accomplishes the seal.
The middle image is of failed ceramic plug tips, and the final image is the general idea of the assembled internals.
If, indeed, the tip is ceramic and is going to fail, it most likely has already happened.
By moving the wire attachment terminal around to find out if that moves the hex section, it will have no ability to cause tip breakage.
If the hex portion flexes around, then failure is as expected, and pulling the terminal and hex away will not cause it to detach either.
Nor will extracting the portion of the heat element above the tip.
I guess I'll have to carefully remove another GP to make sure it isn't ceramic before I go yanking a GP apart while it's still installed. If I find out it's ceramic I will put #1 replacement on hold until spring. What are the odds of ceramic GP with 172k? I think better than even, but not to the realm of impossible.
So far I can't get #2 to budge but I'll take my time. Soak, Soak Soak!
Reference photo of the R428 glow plug.These are not a fast-heat type, but should serve for explanation purposes.