drains bubbling and "sewer smell"

[boomer]

i purchased a home approx. four months ago. the bathroom has two sinks, a tub and a toilet. while the tub and or any of the sinks are attempting to drain. the toilet and sinks make a bubbling noise. also there is a strong "sewer" odor coming from the bathroom. the house was built in the '30's' and the previous owners can not be reached to answer any of the questions that we have. we we first moved in we don't recall having this problem. it seems to have just "magically appeared". any help would be appreciated

[jdewees]

It is very well possible that the roof vent may be clogged.You may have to clinb up on the roof and look inside the 4" vent with a flash light.I have ran into cases where a bird would build a nest in the vent and this would cause a similar situation