Smells

Dear Plumber, Please help!!! No one can seem to fix our problem! We live in a house that is only a year and a half old. Our washing machine started to leak, so my husband replaced the pump. This did not fix the leak and the washing machine also began to smell. We just assumed the smell was something about the new pump since it was an old washer. We went ahead and got a new washer. After it was installed and we started it up, we got the same smell. It is a gassy burning sort of odor. We were thinking the problem had to be something that both washers had—the plumbing. The first plumber came out and said there was nothing wrong to call the Maytag man about a five day old washer. Knowing this was not the case, we did it anyway. The Maytag man came out (and probably thought we were insane) and said nothing was wrong with the new washer but he replaced the belts anyway. This didnt help. Today, we had another plumber who came out. He checked the vent which was clear and also replaced our trap. To our dismay, we are still getting the smell. We are on city water and sewage. The hoses have been replaced on the washer………….have you ever heard of this?? Like I said, both the old and new washer did this and the smell mostly seems to come when the washer starts to spin. Also, we experimented with the washer by taking the drain hose out and letting the washer drain into a barrel. We did not get the smell then. Any advice would be appreciated. This has been going on for over a week now.