If you had been trying to start it cold and the glow plugs were not functioning, you had fuel puddled in the heads, and the smoke was the fuel burning out.
Now that you have glow plugs that work, drive it, let it clear, then try another cold start.
There is a coolant temp sensor, and they do go bad, usually default to -40° when you view it on a scan tool. Be aware, one symptom of a failing PMD (Pump Mounted Driver) is excessive smoke at start up. If you don't have one get one and the resistor ( #5 ) to go in it, a remote mount kit isn't a bad idea either, if the current PMD is still mounted on the injection pump, having the remote kit and a new PMD ( aka Fuel Solenoid Driver or FSD) handy when yours dies could save you a tow bill. I wouldn't change it till it dies though. It is my understanding there is a new design PMD from STANADYNE, but also requires a harness update as well.
Pull your fuel filter, drop a magnet into the cup, if you pull rust and scale out, clean the cup, change the fuel filter, and install a new fuel lift pump ( frame rail under cab ) the rust is from a failing lift pump, it collects in the filter cup, and will work it's way thru the filter element, and will wipe out the injection pump. If the lift pump fails, the engine will run, but it REALLY strains the injection pump.
Metto, you're probably right, the 6.5 cranks don't like the jerking action, another cause of failure was the harmonic dampener failing and not being replaced in a timely manor ( after it starts knocking, you are already working on the crank)
These engines are actually pretty tough mechanically, I've had some come in knocking like they dropped a rod, only to find a broken valve spring or an injector that is stuck open, dumping fuel ( also not good on the crank )
Been a couple years since I've worked on these, I've forgotten a lot. the above is some of what I do recall.
