Freightliner Classic XL blowing white smoke and coughing and fuel tank cracking.

You need to tell us what motor you have, and what tank it is cracking?

 

In my experience white smoke ion start up is almost always a head gasket or cracked head. I'd suggest an oil analysis to make sure coolant isn't getting into the oil pan.

 

If it does this only on a cold start I would suspect an injector. When cold a lot of injectors stick and have low pop pressure which lets them put fuel in the cylinder to soon. This in effect will change the time with out moving any thing is a simple way to put it which would cause the pop and smoke on that cylinder or cylinders. Low pop pressure also cause over fueling because they are not cracking and putting a fine mist of fuel in the cylinder but more of a raw stream. The pop or cough stands out in my mind its probably fuel but could be water or antifreeze as stated above. If the smoke smells like raw unburnt fuel and burns your eyes its fuel. Antifreeze has a smell I can't describe when its burnt with fuel. Another sure way is NAPA auto parts sells a very simple to use kit that checks for combustion gases in the antifreeze. I have only found it at NAPA its very simple to use and only 50 dollars. I have used one a lot its never been wrong for me only requires removal of radiator cap.

 

What year is truck, type of engine? What wore out said could be an injector problem. Mine did that ended up being an injector and the EGR.

 

He has a cummins N14. There is no EGR on a n14 though. I also suspect injector problem. As for the tank, did you check the fuel lines for any blockage?

 

If antifreeze is burning with fuel it has a sweet(not in a good way) kind of smell mixed with the burnt diesel...kind of a gluey smell or an emissions motor with EGR

 

Yea if you have ever smelled it you don't forget it.