[Richard]

It was obvious that we were pulling odors from the holding tank into the coach while driving. I did all kinds of looking for obvious leaks and breaches in the system but found nothing.

Then a long ago thread about vacuum breakers came to mind. The vacuum breakers, or air admittance valves are after the P traps on the sinks. Their purpose is prevent the P trap from being sucked dry when dumping the tanks. The theory of the valve is that it only allows air to pass into the holding tank.

As an experiment, I went to all three sinks and taped the openings closed. Voila, no smell in the coach while traveling.

512 has the Max Air vents, not Fantastic Fan, so even with the vent louvers closed, some negative pressure exists in the coach while driving. It was enough to pull air through the dysfunctional vacuum breakers into the coach.

[encantotom]

like red green says.....nothin duct tape cant fix

tom

[Chester Stone]

Those three inch rubber bathtub stoppers work fine.

[ccjohnson]

No electronic odor control on black tank? And then there is the most important rule, "when you own a Newell, your poop doesn't stink".

[folivier]

According to the manual you're supposed to add salt to the waste tank for the odor control to work.
I just add a couple scoops of Happy Camper when we start to get any odors.

[Richard]

I just realized that I misled the solution. I did not tape the sink openings closed, that would not have helped. The vacuum breaker is after the P trap. You have to go under the sink and tape the opening of the vac breaker closed. Mine had two slots.

Supposedly they are threaded into the plumbing and therefore replaceable. I don't see any evidence that glue was applied to the threads, but they will not budge. I don't want to risk tearing the plumbing loose so I will stick with the tape for now.

[HoosierDaddy]

I've had that problem as well even though I had "disabled" the vacuum breaker. ( Maybe because I allow non-Newell owners to use my facilities ! B-) I found that the trap in the shower dries out enough to let gas escape. I need to remember to run a bit of water into each drain if they have not been used for a while.

[Dmatz]

If you have traps that dry out fill them with mineral oil. The ventless vent fail often I used to keep spares on board dry easy to replace. Newell does not use them any more.

[HoosierDaddy]

Great idea Doug!

[VinceD]

I am having the same issue with smell in the coach. What do these vacuum breakers look like? Are they on all sinks and drains in the coach? Is there one on the washing machine drain? I am tired of the septic smell