My knowledge about diesel is extremely limited. 1989 Jetta, 5 speed, deisel. Starting this past summer, (prior to the summer, every thing was fine, so it's not a temperature thing) it would take 30 seconds for the motor to start after the glow plug would go out. It didn’t matter if the cold handle was out or not. Unburned diesel smoke would envelop the car and then it would finally start with an even bigger plume of smoke. If this was a gas burner, then I would look for something within the carb that was flooding the engine. I know little about fuel injectors and less about glowplugs. Though, the glowplug light comes on and then goes off after a few seconds, could it be bad? Any help would be greatly appreciated, as my daughter is getting to like my car too much.

I would install 4 new glow plugs, I found that the need to be changed every two years or so. The bosch are better than the cheaper ones.