If engine was badly overheated it may have caused oil pump damage. The other option is that dirt has entered the engine oil pan as work was performed and it is plugging oil pump suction tube screen.
What you can try Julio is to drain oil and using air blower with long stem try to blow oil pump screen, then add oil to engine and check the pressure.
okay pavlin let me tell you sometthing i did, i put some air pressure through the oil fillter galery and some air came up through the oil deepstick tube.
is that means oil screen is not plug?
No, i do not think you can clean the sceen like that.
and the problem is my oil pump or oil pump pressure regutor stuck open?
Was the engine badly overheated?
yes it was
Then remove the oil pan and inspect connecting rod bearings and main bearings
If bearing is worn you will loose pressure true that point.
okay then you dont think i did nothing wrong puting heads back together?
No, you did not, but whan overheated badly you must inspect the bottom end.
I mean (when)
hey just question do you think anybady or me by mistake let something like shop rug or piece a paper though any hole in the block went inn to the oil pan and now is blocking the oil screen?
Yes that is what I was thinking. It is a possibility.
I call it a dirt because lots of times things will fell in when working,
okay pavling hey i will take out the oil pan and will see what happen okay hey thank you
Ypu are welcome, All the best to you!
Have a good night, I am going to bed!