whine

Here's my problem: when I start my car, it whines. It will continue to whine until the transmission shifts at around 20mph. the closer I get to 20mph, the louder the whine gets. After it shifts, no whine. What is wrong with my car? It's done this since I got the car, 80,000miles or 4 years ago. I've been told it's power steering, but I don't see how since it does it until the car shifts at 20. Sounds to me like tranny, but I have no clue.

This is the transmission pump whining. I've heard many lumina's and monte's that whined many miles, including mine. While in low gear, there is a boost valve that boosts pressure, increasing pump output, making it whine. This is done olny in 1st and reverse to help keep the clutches from slipping. After it shifts to second, it no longer requires as much pressure to hold the clutches. Ever heard a ford power steering pump whine(not many HAVEN'T)? The trans pump in your vehicle is the same design. I wouldn't worry about it until it turns into a growl.

how costly and difficult is the transmission pump to replace?

You'll more than likely have to remove the transmission, i'm not sure of the price but it will prob. be expensive(the trans has to be removed).