4 plus years, sewer smell finally resolved

[depth5000]

So after almost 5 years of trying everything under the sun to find the source of sewer gas smell in the Keystone Sprinter 5th wheel, we have figured it out.
Our problems started shortly after we purchased it. We would smell sewer gas when we first arrived at our destinations. It smelled strongest in the kitchen when you opened the drawers, and under sink. We did all the suggested fixes such as replace the vent cap under sink, enzymes in black tank, checked vent for obstruction, put cyclone on vent cap, and replaced toilet seal. Nothing helped. No apparent leak at the entrance on the black tank from toilet drain or the vent pipe area.
My husband went on top on rig with a hose.
started running water into vent outlet. It immediately started leaking down the vent pipe sides. So we now know there is a crack or hole, but where? He cut the pipe and tried to pull it up from the roof. It would not budge. After much debate, he cut a hole in the wall behind kitchen cabinet. The cabinet was screwed into the wall and directly into the vent pipe. He was then able to remove the entire length of the pipe which revealed a hole in the side of the vent pipe that had been created with a hole saw.
Replaced entire pipe and sealed roof again. Problem resolved after 4 plus long years.
I will try to attach photos.

[depth5000]

Photo attempt to attach. Newbie. Sorry

[sourdough]

Thank you for posting and I'm glad you found the problem. Sometimes there are some crazy things going on inside these RVs, I'm glad you found yours.

[spicercars]

All I can say is wow. Glad you found it.

[Fish-a-Palooza]

That is great information. Thanks for posting!

[MurphyIRE]

Wow! We started a 12 day trip and the sewer gas was really strong. It kept triggering the alarm (Mostly at night). A couple of days, a flush out and lots of deodorizer tablets and the smell went away. I have a sinking feeling that I might have something similar, but not as egregious.