Sealing drain after removing tub

[dalepres]

In one of our bathrooms, we took out the tub to work on the rotted particle board floor underneath. Since it is just my wife and I, we decided against putting a tub back in and are going to put a linen closet where the tub was.

I cut off the water trap and put a PVC cap on the end of the tub drain pipe. Even so, we still get a wiff of sewer gas from time to time. For now I have to leave the bathroom window open and door shut until I get this sealed propertly (not fun at 0 degrees). I've done a lot of PVC pipe work, replacing all the gray stuff in this trailer and having put in many garden sprinkler systems, I've never had a PVC joint leak water.

So what did I do wrong here? What do I need to do in order to completely and safely seal this drain pipe?

[Greg]

Capping the pipe is pretty cut & dry, I would check to see if there is a crack in the pipe or possibly an under the counter vent leaking.
You could throw some duct tape over the cap and see if that stops the smell, if so try another cap. Greg