Cat 12 Cooling system

I have been working on a 1946 12 grader for quite some time and finally got to run the freshly overhauled pony engine yesterday, my concern is that the left side of the pony engine (water pump side) gets a lot hotter than the right side, I can hold my hand on the block on the right side but not the left after it has run for a few minutes. SO my question is: Is the cooling system air locked? I did bleed the air out of it as described in the owner's manual or is there some other trick to this? I also did have the diesel engine cranking over to help circulate water.

Water pump side is considered to be RH side. Did you check/clean/clear the cross over waterpassage in the bottom of the pony block? Seems your not getting circulation to the LH side.

I had everything cleaned and checked over, I will probly have to pull the pony back off the diesel and make sure a rag or some thing did not get stuffed in there.