Check the grounding strap.

I've used these for at least 40 years now. I keep this one ready if I need a spare.
Works on water pressure for the adjustable fill height. So simple to install...just this one part and a flapper.
No more float needed.

http://forums.pelicanparts.com/uploa...1672776264.jpg

Call me crazy or whatever, but I sit to pee. I'd rather do that than get pee all over the room. A friend was on some meds once that turned his pee orange or some other color. He was shocked to see where all the pee actually went. He started sitting after that. I'm just lazy and want to take a load off.

Black toilet? We had one in my house in the 70's, it matched the black sink and black shower stall.

How long has it been since the shower in the bathroom has been used?

I occasionally have a similar issue in a seldom used bathroom. Toilet level drops and when the unit is flushed I can actually hear noise from the shower drain. Run the shower for a few minutes, and the issue goes away.

I suspect the trap on the shower is drying out? Don't know how it all works, but will only take a few minutes to test.

Your vent line between where this is and the stack is plugged. Either a bird or something has made a nest and plugged it up. When the toilet flushes, since there is effectively no venting on the sewer side of your toilet (and P trap - the curves under the bowl), the inertia of the water flowing down continues to pull the fluid with it until if sucks air from the bathroom to break the siphon. Since the water level in the P trap is low enough to allow it to suck air, the smell you are getting is sewer gasses coming back into your house.

This has nothing to do with the valves in the tank and everything to do with your vent stack and the related vents.

Look at level 2 in this scenario… if that blue vent line between the toilet and the vent stack plugged up, you would have your exact problem.

http://forums.pelicanparts.com/uploa...1672824539.jpg

The true test would be to unmount the toilet and do a bench test to find the natural water level in the bowl without influence from vent lines.

Just listen to this. This is your problem. The vent is plugged somewhere.
Don't overcomplicate things.

Best
Les

Interesting....I didn't think of that. Will investigate today, I'm off work.

My house is a one level ranch style. 3 full baths, 1 at each end, the center hallway unit is the toilet with the issue

Agreed, and if your stack is plugged this will still cause your issue. If the stack is plugged, it’s using a shower or sink drain as your vent and the stinky smells are coming in.

Think about the rate when a toilet flushes vs. a sink or shower. That sudden fast rate is faster than a plugged vent can match.

A simple test is to actually blow the shower p-trap (or sink) out so there is no water in it, then flush your toilet. If it has the correct water level (because the shower or sink is your new vent) you’ve proven the vent is plugged.