What is the most likely cause of excessive white smoke from a 83 300D?

White smoke on startup when cold is also unburned diesel fuel. What is happening is the fuel is getting hot enough to vaporize but not hot enough to combust. In the FDNY we call this condition a "white Ghost". WE see it occassionally in the basements of apt buildings that heat with oil. Very dangerous because give it an ignition source,IE boiler kicking on and Boom!. The basement explodes!
I have a Nissan diesel in my 1980 Scout. Smokes like hell (white) when starting. I can signal Indians its that bad. Cause there is twofold. Glow plugs only heat to a max of 800 degrees (bad choice of plugs) and there is no advance unit on the injection pump (manual or vacumn). Centrifical advance only kicks in above 2000RPM so once it starts, you keep it to the floor to hit that RPM and hold it there a while. Eventually the white smoke clears. BY this time, the neighbors have called the fire dept. Drive away Quickly!
In your circumstance, make sure all of your glow plugs are actually heating up. 1 or 2 bad will give you all sort of problems. I usually buy 5 new ones when I bring home a new MB and test the old ones on the bench. Any testing still good I keep as spares. HTH. MIke

thanks for responding. I do not know anything about this motor as I just bought it along with the tranny from EuroAsia in Wichita, Ks. I have installed it in my 54 ford pickup. Have not had it out on the road yet so not certain of the tranny. The motor starts very well but smokes (mostly white). The smoke seems to lessen as the motor worms up. It does not overheat - in fact it does not seem to get hot enough. I changed the thermostat and after 15 minutes of warming it up the temp guage does not go past 150. Bob at EuroASia claims it has 300 psi compression in all cylinders. If it had a cracked block or head gasket would it effect the compression?

How did he check the compession, Thru the glow plug hole? Make sure all Glowplugs are getting cherry red.
After its warmed up its still smoking white? Fuel Quility is good? I have heard that burning "red" fuel causes them to smoke a little more
Temp should go to 180 degrees. I assume your using an aftermarket gauge. Take temp from sender port located on side of block near injection pump.
I like you choice of vehicle. I put a MB diesel in my 73 International Travelall. Works great. Have a total of 4 MB's in the family now. Best engine ever designed ! Keep me posted. Mike

diesel burning is light blue. some call it white. it is distinguishable from water in that water vaporizes quickly and diesel fuel smoke sort of drifts away. it typically happens only on start up if you have a bad glow plug or two. rarely it will smoke after it is warmed up if you have an injector that is leaking too much.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.