Sewer smell when bathroom exhaust fan runs

[Birdfan]

My 2014 Greyhawk FS has an unusual problem. I've had many MH's, including Monaco Sigs, but have never encountered this smelly disappointment. When parked and with the bathroom exhaust fan running a sewer odor is VERY evident outside and around the motorhome. This happens even though I'm not on a site with a sewer connection. In fact, it does it while in my storage bus barn.

Any ideas?

[eldermike]

Will the toilet hold water on top of the seal?

[Jagiven]

It sounds a bit like a bacteria bloom, but here are a few questions. Does any of the cabinets smell? There is a vent cap inside one of the cabinets, to relieve pressure. Sometimes the cap’s spring sticks it partially open. Do you keep a few gallons of water in the sewer holding tanks all the time (even between trips)? Every spring I get a sewer smell build up a couple weeks after our first use. It is from a bacteria bloom. Do not put bleach down your drains or you will kill any bacteria, and you have to start over. Do you use any toilet chemicals? If so, try changing to a liquid version that does not need to be dissolved. There is also a version for the grey tank, I have never used it, so I do not have any experience with it. This question maybe way out there but, have you ever noticed while in camp, any fluids under the MH at the tanks? Just wonder if you a leaky tank, causing an odor.

On my HTT I found as we drive my shower drain sloshes out some of the water from the p trap, causing sewer gasses to be able pass through the trap and get pulled in to the bathroom, especially if the fan is on. We now make sure to add a little water to the drain when we park or make sure the tub drain is plugged.

[moonraker1]

Had the same problem with the cheap plastic toilet in our 2008 greyhawk . Replaced it with a ceramic toilet .
The plastic ones tend to crack The toilet is taller and the bowl is deeper .Easy to change and under 200 dollars

[TX_Arvee]

Couple questions: Does the inside of the coach smell as well? Where is the location of the over pressure vent fitting (under kitchen sink or bathroom), Is toilet holding water? Does smell happen all the time or only when toilet is flushed? Are you suing chemicals in black water tank? Liquid or packets?

I have had more issues with my grey water tank than my black water tank. If I run the fan, i get the blackwater smell after flushing, but that is simply because I am pulling fumes right out of the tank. If fumes continue to come out of toilet after flushing and filling with some water, something is wrong with the toilet.

This leads me to believe the problem may be a foul smelling grey water tank and the dang overpressure vent valve located on the sink drain. (mine is in the kitchen). The fan will pull enough vacuum pressure on the coach to open that vent relief valve and pull fumes from the grey water tank. RV plumbing code requires these things and for the life of me, I dont see the use. If you have a functioning roof vent, this vent does nothing but cause service issues for the dealership to trace odors to.

Find the vent relief valve and rubberband a heavy ziploc bag over it. See if problem persists. If it doesnt, the smell is getting suck out of the greeywater tank.

Fill and drain your grey water tank numerous times, if you have not already. Add some pinesol or greywater tank treatment and fill tank to full. See if problem persists. A full tank will stink less than an empty one if the water is foul..

My money will be on it being that vent valve and grey water tank.

[Mustang65]

Originally Posted by TX_Arvee

Add some pinesol or greywater tank treatment and fill tank to full. See if problem persists. A full tank will stink less than an empty one if the water is foul..

Try adding Pinesol to the gray water tank... if you do not smell the pinesol, try it in the black water tank.. that should tell you which one is generating the odor
Don

[Raugustin]

Hi Mustang65,

I'm curious as to how you setup your AirSight Wireless IP Cameras to work as backup cameras. Would like to know if they work well and how you configured them.

Originally Posted by Mustang65

Try adding Pinesol to the gray water tank... if you do not smell the pinesol, try it in the black water tank.. that should tell you which one is generating the odor
Don

[exjay1]

Originally Posted by Jagiven

On my HTT I found as we drive my shower drain sloshes out some of the water from the p trap, causing sewer gasses to be able pass through the trap and get pulled in to the bathroom, especially if the fan is on. We now make sure to add a little water to the drain when we park or make sure the tub drain is plugged.

This ^ . Also its possible if there is long periods between use that the water in the P traps can slowly evaporate allowing gas to escape.

[Birdfan]

Yes

[Birdfan]

Replaced and installed ceramic

[Birdfan]

Tx rve
The smell is only outside. Don't know where valve is. Doesn't smell on flush. Smells only when toilet has water on top of seal and the exhaust fan is turned on. I believe it's the gray tank, too. I'm going to add Pinesol to the tank and see if the odor changes.

[Chakara]

Could your fan be running the wrong direction? That issue sounds odd......

-Kyle

[jayflight25rks]

My Jay Flight has the sewer smell when the fan is running. I changed the flange gasket.... no deal.... disassembled the toilet, inspected, flushed tank, reassembled..... no fix. I finally discovered that the smell is coming from where the flush cable exits the rear of the toilet to operate the water valve. I don't think there is a repair kit. I am replacing the toilet.

[Mustang65]

Question: Wen you get this odor, do you have any windows open? IF NOT the fan will pull air from any where it can, even the air vent for the "P" traps under the sinks.
Don

[Seann45]

My smell from my TT went away when I replaced the toilet. I am fairly sure it was drawing air through the toilet seal, the floor seal not the valve. Always try replacing the installed foam seal with a proper wax one as a first resort.