E300D Cold Start Troubles

[Jerzeeshor]

I have a 1996 E300D (#210.020 chassis with #606.912 motor) with 77K miles. All glow plugs were replaced at 50K miles when the pre-glow light would not go out even when warm. Other than that, it's been a great vehicle until during a highway drive the first cold spell of this season, the check engine/engine electronics warning came on. No glow-plug indicator problem. Cold starting after that was alittle difficult, with some white smoke and diesel nailing noise at idle for about a minute or two, but a trip to my local M.B. tech resulted in the #4 glow plug being replaced, along with the pre-glow module, per the fault codes found. As an added cold weather precaution, I even had him replace the battery and change the oil to Mobil 1 0W-40. I noticed the glow-plug indicator took alittle longer to signal ready-to-start, but otherwise worked OK till the weather really got chilly and then cold starts became rough including white smoke, some diesel nailing noise at idle, alittle raw fuel odor from the front engine compartment, and erratic idle until warm. No dash warnings at all. Car runs great when warmed-up and started without trouble even on a sub-zero day with the block heater plugged-in. Since I can't plug it in at work, I took it back to my M.B. tech who said the glow plugs and module were fine, but the injectors needed to be replaced. Got it back from the shop yesterday with six new injectors and two new fuel filters. Motor sounded like a tank, but the tech said to drive it a bit and the new injectors would quiet down. Went to start it this morning without the block heater and it's even worse than before! If it was summer at the Jersey shore, I could have killed every mosquito in the neighborhood with the clouds of white smoke! And the neighbors could have killed me with the louder-than-ever diesel nailing noise! Used the block heater for about 3 hours, and it started easier, but still alittle smoke and still alot of nailing noise at idle. Took it out for a good long drive and it runs great, and no dash warnings have appeared. Any advice? Thanks!