I want to tell any newbies to diesels out there about my experience. I bought an 83 240D in early September. It has always started fine in our somewhat warm but variable Memphis, TN climate. It was always rough on startup but smoothed out after 30 seconds or so. A couple of weeks ago, on our coldest day (the first full day it didn't get above freezing), my car would not start no matter how much I cranked it. I first suspected my glow plug relay, so I verified I was getting voltage to each glow plug and I was. I finally had to get starting fluid to get it home. After fiddling with this thing for a week, I broke down and bought four brand new glow plugs from Autozone ($10.99 each for Bosch). As I took each one out, it dawned on me that they are basically like a light bulb in that they have a filament on the inside of each plug. I tested each one for continuity using the "ohm" setting of a DMM, and found that three out of the four would not pass voltage through them! I still have the cuts on my hand from changing the glow plugs out as it is a PITA to get to all of them out because of the injector lines. However it was worth the pain. It was below freezing when I changed them out, and the car fired up to a smooth idle after 20 seconds of glowing. Car starts impeccably now. Take home lesson is CHANGE YOUR GLOW PLUGS if you haven't already. They are just like light bulbs - they have a limited life and do burn out.