Black tank smell

Driving with a side window open that is near the front of the MH, like a driver's or passenger's window, can cause this too. There is low pressure outside those windows while driving and it draws strongly.

A couple of weeks ago ,we were coming home from a trip. We noticed that the we were getting a very noticeable smell from the Black Tank. We stopped to get breakfast and a cup of coffee. We saw that the vent with the automatic fan over the cab-over bunk had come open,(don't know how being as we don't use that bunk except for storage) When we went back to the RV we made sure all of the vents were closed. All of the vents including the one over the cab over bunk. We did not have any odor all the way back to the house.

When I had the same issue A friend suggested this. Prior to a good long drive. Fill the tank 1/4 full with water, double the amount of what ever black tank cleaner you use and 40 pounds of crushed ice. The ice will scrap around and knock the build loose, the ice melts and it all drains out.

Worked for me and I still do it once a year.

bill.ritchie wrote:
One question about the vent... I went up to the roof. It appeared ok but I couldn't really check anything without completely removing the cap, including the caulking. Is there an easy way to check that the vent is clear?

You can check your roof vent to make certain it is clear by taking your hose on the roof and running water down the roof vent. Make certain you have your black tank dump valve open when you do this test.

-Tom

The vent can be blocked from below too. Tank too full, or something plugging the vent. ISTR the vent can sometimes break loose and fall down into the tank. Hope nothing like that for the OP and it clears up.

I use the little packets of tank powder to help and run with some water to help desolve solids and only open black water valve when dumping.

One question about the vent... I went up to the roof. It appeared ok but I couldn't really check anything without completely removing the cap, including the caulking. Is there an easy way to check that the vent is clear?

No fans are on. Always add a couple gallons + cleaner after every use. Valve is shut. I'll have to check the vent pipe.

Also you don't just have the black tank valve left open do you? You get sewer gas into the tank if you do this. It can be prevented by creating a trap in the black line depending how you route it, but the better answer is to keep the black tank valve closed except when emptying the tank.

Jim

Possibly the vent pipe is blocked. Climb on the roof and make sure there are no obstructions.