I have a 83 300 D turbo Diesel that I  recently rebuilt. I replaced the crank bearings, rings, rod bearings resleeved the engine . I checked  the bearing clearance an they range from .25 to .51 within the main bearing.The rod bearings were within the same limits. also the oil pump was replaced with oem unit. Oil pressure gauge is around one to two bars which gives me concern. The only thing I can think of is when putting the engine back together I used assembly lube between the bearing surfaces instead of oil. Camshaft oilers are not squirting.  What could be causing the low oil pressure condition other than bearing clearances?