smell?

The air gap at the top of the pipe is there for a reason... it provides an air break to prevent the machine syphoning out, if you bung it up the machine could continuously syphon out when on rinses.If the down pipe has a water trap at the bottom no smell can come back up. Probably best if you get a washing machine sanitiser from the supermarket.

Kenjo
April 2014

Is it possible that the waste pipe is open at the top? (The washing machine's waste pipe is pushed into a wider diameter upright pipe which has an open end. This is quite often the case.)

You can get a smell from the dirty waste pipe. Try sealing the gap between the upright waste pipe by using old cloth as a bung. Push the cloth in to seal the gap between the smaller pipe and the larger one. With no gap you won't let the bad air out from your kitchen's waste pipe.

Duke
April 2014