Originally Posted by Diseasel300

White smoke + overheating strongly suggests timing problems. Late/retarded injection will cause white acrid smoke (it'll sting your eyes) and have a foul smell. It will also cause excessively high EGT's and overheating from lugging the engine.

Originally Posted by Diesel911

If the smoke smells like raw fuel that is an indication of late timing or for some other reason the fuel is being atomized but not burning.

Put a piece of cardboards or board near the exhaust and remove it so you can smell it.

Note that it has happened before that people have acquired Engines that were not in good shape for transplants.

Originally Posted by OM617YOTA

No input beyond what's already been added, smell the smoke to help narrow things down.

Good luck. Went through quite a hassle getting my swap ironed out myself - it was well worth it in the end.

Originally Posted by Maxbumpo

If you didn't swap over the MB radiator to go with the diesel engine, I'd say you need to probably take a hard look at that, you need to make sure what ever radiator you have is up to the task. Easiest way is to use the MB radiator, just a matter of fitting that into the truck.

Replace the thermostat and the gasket, they cost about $20 or so. Be sure to check the old and new thermostats in a pan of water on the stove to make sure they open at correct temperature and reach full stroke by correct temperature.

Did you change the injection pump timing at all? Getting the timing off can lead to the white smoke and may also be related to the over heating.

What does the white smoke smell like? Sweet smell = coolant, unburnt diesel smell = injection problem (timing or bad injector(s)).

Originally Posted by MCallahan

Sounds like a coolant leak into the intake. Smoke on start as it seeps in and puddles overnight. White smoke and overheating as it gets under load and the system pressurizes. Put a cooling system pressure check on it.