Not to hijack this important safety message, but the first picture in Whunter's post shows four glow plugs in various stages of glowing. The one on the far right appears to be fully activated after only 2.0 seconds, at least according to this photo. Should it take only 2.0 seconds for the glow plugs in a 617 engine to be fully active and hot?

The reason I ask is that a couple of weeks ago I tested my glow plugs in an effort to remedy rough cold start problems, and when I hooked each of them up to 12V they did eventually glow white hot, but it took more like 8-10 seconds for them to reach that stage. These are Bosch GPs that I bought about 6 months ago. I thought this was normal and moved on, but is it?

If it matters, the resistance of the plugs were between 1.7 and 1.9 ohms. I reported the results here on the forum and based on the replies I received I decided that the plugs were ok and that it was more likely an injector problem.