[QUOTE=fender_bender;3161037]Its that point when you stand up and look at your car and think, "....I'm screwed." So I was working on my glow plug issue on My 300TD and I found that the glow plug in cylinder 2 was dead. The wire tested good. I tested the relay and the fuse and all looks good. I went to take the plug out to test it further. Put the wrench on and it wouldn't budge. I soaked it in pb blaster and tried again. I thought I felt it turning, but it was actually rounding the nut. So I tried using more pb, hit it with a hammer and screw driver to loosing it up, tried the wrench again and it just turns on the nut. I tried the splined end of the wrench and still just a spinnin'. I was using 12mm wrenches. I got an 11mm wrench and was able to get it on the nut and tried to give it a turn, but I messed it up further... I'm screwed. Any suggestions. I guess I could take it somewhere and have them remove them all.

Another question. Would one bad glow plug take the whole system down?[/QUOTE]

No.
But, if your Engine is having poor starting due to low cranking speed and poor compression (this could be due to the need for a Valve Adjustment) the loss of one Glow Plug could cause a problem.

On the Older Loop/Filament type Glow Plugs when one goes none of them will work because it breaks the circuit or burns the Fuse.

__________________
84 300D, 82 Volvo 244Gl Diesel