I don't see how any toilet - save one on a boat or R/V - could possibly function without a vent stack. "but the vent goes to the garage" would not be approved by any building inspector anywhere in this country. Perhaps it was a "SPOT" - stupid previous owner trick. There is one possibility - other than installing a toilet and vent properly - which apparently was not done. The vent or soil pipe could have been pierced by a drill, nail or screw, especially if PVC was used. As an appraiser. I've seen that happen before. And yes, I *almost* made that rookie mistake myself, installing a new cabinet over the toilet. Since this is a 1938 house with plaster on lath walls, I was using a stud finder and drilling pilot holes. One was in an unexpected location, but it was *perfectly* placed. But it wouldn't drill...and that's when I realized it was the cast iron vent stack. No harm done....

First off, that is not a J-bend. A J-bend is a straight length of pipe with a 90deg bend on the end. The pipe is question here has a 180deg bend and it is properly called a "Return Bend". When that return bend was initially made they began by making a straight return bend without a cleanout hole. They then drilled a hole at the cleanout location slightly smaller than the desired finished opening and the tubular brass of the bend was then swaged out to form the finished shape and size at the cleanout location. A short piece of threaded brass tubing was then inserted into the opening and soldered in place and finally they screwed the cleanout cap on the end of the threaded brass tubing. In this case over time the threaded brass tubing corroded and fused into the cleanout cap so that when the cleanout cap was turned instead of the cap unscrewing the solder joint broke and the treaded tube came out of the return bend. If you examine the section of brass tubing extending out of the cap in the last photo you can see where it was originally soldered into the tubing. That problem is quite common when working with old tubular brass fittings and generally Plumbers do not even attempt to remove the plug, but rather they take the entire return bend off to open the line for cleanout. It was mentioned that this is an "S" trap, which is illegal, but that is not correct. It is true that S-traps are now prohibited by code and may no longer be used for Plumbing, but here we run into an issue of semantics. "Plumbing is defined as the act of initially installing a piping system whereas the act of repairing an existing system is defined as "Maintenance". When performing Maintenance we are required to maintain exactly the original configuration, therefore given that an S-trap was code approved when that line was first installed you are required to replace it with an S-Trap. If you were to move that sink or do a rehab on the bathroom that involved changing the location of any fixtures or the physical configuration of any of the piping you would then be performing an act of plumbing and as such, all plumbing within that room would have to be brought up to the code that is in effect at the time the rehab is performed.

If "gas meter thing"plumber brought is for detecting natural gas I believe you are on the right track. The utility companie's line might be leaking with gas following your servce line into dwelling. Adding propane to raise line pressure during coldest part of day is common pratice. If you feel compelled to help plumber locate the problem try this. Fold a clean cotten cloth several times and hold it against outlet of grill tank. Make certain to keep tank upright then open valve for 2 or 3 secounds. Does cloth smell similar to odor in basement?

HA! I would LOVE a plastic bag!!! Like the Bubble Boy! I kid. I don't want to kill anything...I just don't want it in my house :) I feel better now that I realize how the damper and screen work. I don't know if they are yellow jackets or wasps...i just know that they seem to love my sunny gutter which isn't that far from where the vent return will be. I'll just have to keep an eye on it and make sure I flush the gutters out with a nice burst of water from time to time. I also didn't realize that the vent hood has a damper and then the duct exit also does. That is good to know!