Here's the deal, I just got my 87 D150 318 up and running after a month of headaches and part chasing (I have a fairly extensive thread on it here).
Now I'm noticing a descent amount of white smoke from the exhaust. The truck had sat for at least 2 years before I got it, so I'm hoping it's just due to the seals being dry. It doesn't seem to be losing any coolant or have any oil leaks, but it still worries me that it's smoking this bad.

What should I look for to eliminate any potential major problems?

 

white smoke is usually moisture. maybe the gas in the tank has gone bad from sitting for 2 years.

 

I agree, white smoke is always moisture, I will look for your previous thread to see whatcha done to her

 

Alright, that didnt help me haha....your engine is burning coolant or water from the fuel tank or lines,( there might also be a possibility that there was moisture in your exhaust system and it is just steaming as it evaporates but this will go away after awhile if this is the case)
Pull your spark plugs, see if one or more doesn't look right, next I would pull your valve covers and see if you have white milky crap inside them....let us know what you find

 

Thanks for the advice. I had intended on doing the valve cover gaskets soon any, now I have an excuse lol.

 

If you think you might have water in your oil the easiest way to find out is the dip stick. Pull the stick when the engine is hot and smear the oil on the stick on the hot exhaust manifold. Any water will immediately start the boil while the oil will just smoke. This trick will show water even before the oil can get milky.

 

I just changed the oil with Castrol full syn and a Bosch filter.

 

I took it on a about a 15 mile round trip today and it seems to have cleared up. Looks like I got lucky and just had some moisture in the exhaust or the old fuel.