When I run my 2nd floor washer, the drainpipe makes a leaking sound (drip, drip, drip, etc.) I can't find any signs of leaks on the 1st or basement levels. Any suggestions. The drain pipe is PVC.

Try pouring some water down the stand pipe when the washer isn't running. If you don't get the drip, drip, drip, maybe the vibration of the washer is shaking a little water out of the trap and down the drain. If you do get the drip, at least you can study the problem more without having to run a load of laundry.

Thanks for your help. I'll give it a try. :)