Septic odor from washingmachine

[cowie1]

In attempting to eleminate this odor, I installed a p-trap in the 2" washer drain line where it enters the house. However I still have these gasses getting into the laundry room, could they be escaping thru the p-trap??.
I cannot find any vent in the washer drain line, and if I extend the line to the roof to vent it, will it be nessary to install a new p-trap in the line closer to the washer??.

 

[Paul Barker]

might be cheaper to use a hepvo trap for the washer, which seals without water so doesn't suffer loss of trap through suction..

 

[ladyrose]

Hi
Could the smell be from the machine itself? 200 ml of vinegar put through a 60 degree wash will clear limescale ands scum, or any of the shop bought products. Failing that, turn the machine on it's side, remove all the plumbing bits and clean out thoroughly. Horrid job. I have an ancient Zanussi and my husband has to clean it out once a year.