i have some blow by every now and then worse after 30 to 45 min of driving
also it trails light blue smoke most of the time

the short block is brand new less than 500 miles
had local head shop work head and deck it

i put the springs and seals on it the seals didnt fit like i they should i didnt force them on the guides that could be my problem

 

it might be because the rings havent set real good yet and it might just take some time to get it broke in, thats if im right in assuming you completely rebuilt the engine when you put it in your truck. just throwin some ideas at ya.

 

it takes a while for the rings to set in a diesel - one thing that helps them seat is hauling or towing something sort of heavy. I have been told (don't know how true it is) but it takes about 30k miles for them to seat fully. Now having done rebuilds on many diesels that I have owned over the years I didn't get much blow by or smoke out the exhaust pipe right after I started her in service. might be wise to do a cylinder leak down test just for grins and giggles...

 

the blue smoke might be just excess oil you used while assembling it, although im not sure it would last for 500 miles that you have on it already but just a thought