My dad called me today and told me his truck just started smoking. He said that sometimes it's so bad it makes the person behind him have to slow down. Other times it just does a little. I guess it won't do it while in neutral or doing a brake stand. But, only really when he gets on it doing about 30 or so. What could it be? OH, and it's a '00 7.3l. It's a black smoke by the way. Could this be normal?

 

smoking is bad for your health

could be dirty fuel. the balck stuff is probably diesel soot.

let him run the tank dry and re-fuel at a different station and see what happens.

 

Replace air and fuel filters for starters. Check intercooler boots.

 

Check the codes..

 

I would be inclined to say fuel filter or injector o rings leaking.