I have a 06 Ford F-360. I was driving down the road when my truck started pouring black smoke. I shut it off and tried to start it back. When it finally started it was pouring white smoke. It was rough to start. Sounded like it was locked up but if you hold the key over for a few seconds it would finally crank over. I was told it was the high pressure oil pump but I'm not sure. Any ideas on what it could be?

 

To me sounds like you got a bad injector that is leaking. The way to test it, is doing both a injector solenoid test and cylinder contributions test by killing one injector at a time. But you need specialized diagnostic tool at either a mechanic shop or dealer.
I would do this if I were you to save time.
There might be ways of doing it without the use of diagnostic tool but it ll take time and can be a pain.
But if I were you don't drive much, because it sounds like your hydro-locking some what. And that excess fuel can also burn up your piston and rings and valves.
But if you decide to bring it in to a shop and get it checked (for about $100 some if not less) and if I'm right, they tell you which injector failed and you can perform the repair yourself to save money.

 

I'm saying fuel related and not coolant cause of the black smoke. And the white smoke afterward must be excess fuel not combusting at the right time and/or excess fuel dumped in the exhaust system. White smoke is not always coolant, for those who might get in into this conversation.