97 3800 engine squealing noise

hellol,
we are really stumped on this `97 3800 buick we are working on

we swapped the dead original 3800 engine out for a real low miles junkyard 3800 and its been bad luck ever since, we have had great luck with all the past 3800 engine replacements until this one now..

it has 40 psi oil pressure when cold
runs great
but when it gets all warmed up the front of the engine will start to make wierd squealing noises
if you rev it up it will go away for a second then return by the time the engine returns to idle speed again
we removed the belt and ran it and it still does it
its something in the front of the engine
we also tried another balancer, that changed nothing either
we cannot figure it out

the oil pressure sits under 40psi when warm, but i still suspect possible oil pressure/filter problem ?
it seems ot be starting to develop some bottom end ticking also, and a little bit of a knock almost when you are listening under the hood and rev the throttle by hand

is there any kind of issue with the oil pumps on the later `90's 3800 engines i need to know about


we dont know what to do now short of pulling oil pan and/or pump cover and replace the pump and inspect the pan

I'd pull the timing cover off and look at the thrust button on cam shaft.