Wierd sound like running water? Water pump or oil pump?

Ok here it goes.

92 achieva 3.3l v6. 131k

I bought this car about 2 months ago and love it, but there are a few problems.

I think this car had been sitting for a long time becuse it was pretty dirty, I had the oil changed and tried to clean her up the best I could.

Problem is oil pressure goes from 30-70, with no performance problems, but the check oil light comes on spiraticaly.

Problem is the "low coolant" light came on 2 weeks ago so I put in about 1/2gal of antifreeze, I didnt have any leaks, so I checked my Oil and it seemed OK. Now this week I hear what sounds like my water pump grinding, but only occassionaly. Now today I hear a sound like water running when I started it and it contined as I accelerated.
My temp gage never went above 160.

What do you guys think? Could the sound of running water be a problem with my radiator?

Thanks