I recently bought an older mobile home and can't seem to locate the air vent for the toilet or sinks. the mobile has been added on to and a new roof which covers the entire addition and original mobile. could not find any vent in the attic .there is no smell and the toilet flushes ok into a septic system. could there be a cheater vent underneith the mobile some where ?

 

There could be Air Admittance Valves on the sinks but the toilet is a different story. Don't even think they make one for that. It should be the only pipe coming out of the roof. They usually stick up about 12 to 15". Check the area where any toilets are. This is usually the biggest pipe in the home so they use it to run the vent stack up and out of the home. Let us know what you find. Good luck.

 

i have looked on the roof and there is no vent stack. as mentioned earlier a floating roof has been built over the mobile ( almost like a car port ) and the mobile home still has its own roof. I thought that it may be venting from the original roof into the new attic roof, but i looked up there and can't see any vents .hope i have not confused you. maybe my question should be how are toilets in motor homes , campers & mobiles vented. I just see a drain pipe out of the toilet into the septic system. The main drain line runs about 10ft max. The toilet flushes but not with the same gush as a normal toilet should have. is it possible its not vented because of the short run and there is enough gravity without air pressure to get the job done?

 

If there is not a ventline, the possibility for a trap in one of the fixtures being sucked dry is high and this would let sewer gas enter the home. Try filling the bathtub with a few inches of water and then drain it. While it is draining, look at the water in the toilet bowl. If there is no vent, the water will be moving. Since I cannot see this home, I have to guess that it is possible the previous owner hid the vent. It would be a lot of work to remove it completely.