I am working on a 87 turbo diesel 603 motor in a 124. Complaint is on cold start engine starts up runs rough and dies. It may take 3 or 4 tries to keep it running, depending on ambient temperature. After start up you get a lot of whitesh maybe little blue smoke, but smeels like raw diesel fuel, incomplete burning. It takes a good while for the smoke to clear up, but really never goes away completly. After the car is warmed up it runs good. The cars has 300,000 miles on it. The glow plugs were replaced at another repaire shop under customer request, this did not make any changes. First I did a compression test I had readings of 475, 550, 550,525,475, and 500 psi. I thought this was acceptable. I did the compression test at the injector nozzle ports so while I had the injectors out I bench tested them, A couple of them did not have a good pattern. Customer wanted to replace the set so I put in a set of rebuilt, the all looked good on a bench test, no improvment. next I checked pump timming it was at -17 deg, I advanced it to -13 deg no change in running. When I had the injectors out I did a visual of the glow plugs, they were all getting very red. Hooked up a alternative fuel supply this made Know differnce. Checked cam timming, to my surprise it was really close to spec. Checked EGR valve and bypassed it to make sure it was noy coming open, no problem found. Removed intake to see if the intake valves were carboned up, again I was surprised they were cleaner than I expected. At this point I suspectd a injection pump , put on a rebuilt MB pump, no change. I tried advancing the timming of the pump to -10 deg no change. I have not seen any indication of air in the system, and the car never has long cranking it fires right away , but like I said earlier it will run ruogh for about 15 maybe 20 seconds and die. I pulled the 50 circuit wire from the glow plug relay connector so they would continue to glow after start up , this seem to help some. Car uses about a quart of oil every thousand miles and as had no coolent loss. Any info may help. We are thinking it might be somethig mechanical, but have not pulled the engine apart at this time.