I have an 84 6.2 K10 with around 102k miles on it. When it is cranked it blows a lot of greyish smoke at least for a few minutes, unless you immediately start driving it, then it clears up. The truck does not smoke heavily after it has been ran.

The truck does not get drive that much, maybe once a week. It is usually worse after it has been sitting a while.

This is the time of year to check the glowplugs. Ohm meter should read .4-.8 engine cold, 1.4 ohm warm. Some glows also light faster than others. There are many other posts on this, look back a day and read them.

So are you saying that it is only the glow plugs not heating up enough? The truck will also begin to smoke after it has sat idling for a while (I assume the operating temp has dropped)...

It does this to some extent in the summer months, too, so that was why I wasn't really thinking it was the glow plugs, plus it is not really that difficult to start when cold.

Check fuel supply pressure, and fuel filter...a weak pump (less than 5 psi) or plugged filter will cause internal advance movement to be slow (retarded) and smoke white. If this checks out, or if you correct it and the problem stil exists, try advancing the injection pump a touch.