Vent clogged or obstructed?

[RudysWorld]

When emptying the gray tank I noticed that it will flow fairly well then slow, followed by a whoosh sound and then drain completely. Also, after dumping the black tank I am noticing an odor. After reading through the forum I thought it might be a vent clog causing both issues.

How would I clear the vent?

If you think my diagnosis is off what do you think it would be.

Thanks to all!

[Trempert]

Originally Posted by RudysWorld

When emptying the gray tank I noticed that it will flow fairly well then slow, followed by a whoosh sound and then drain completely. Also, after dumping the black tank I am noticing an odor. After reading through the forum I thought it might be a vent clog causing both issues.

How would I clear the vent?

If you think my diagnosis is off what do you think it would be.

Thanks to all!

Regarding the gray water tank...if you get a clear connector, you will see that you hear the water flowing until the discharge tube is completely full as it can't keep up with the flow out of the tank. No air = no noise. Then, once the tank is empty you'll hear the whoosh sound. Nothing is wrong. This tends to happen most when the discharge hose is has to run uphill into the sewer and is only slightly below the holding tank discharge level.

Your black may be the same issue. I would highly suggest a clear connector as you can also tell when your black backwash cleaner has completed its job.

[puff]

what Tim said..!..x2

[Falcon35]

Originally Posted by trempert

regarding the gray water tank...if you get a clear connector, you will see that you hear the water flowing until the discharge tube is completely full as it can't keep up with the flow out of the tank. No air = no noise. Then, once the tank is empty you'll hear the whoosh sound. Nothing is wrong. This tends to happen most when the discharge hose is has to run uphill into the sewer and is only slightly below the holding tank discharge level.

Your black may be the same issue. I would highly suggest a clear connector as you can also tell when your black backwash cleaner has completed its job.

x 3

[Herk7769]

One add. From your post I think you are under the impression that there is only one vent. In fact, each holding tank has its own vent.

That vent is 1 1/2 inch tubing. The dump valve is a 3 inch outlet. A full gray tank can output more water faster than air can be replaced. This will continue, causing a slight vacuum in the holding tank, until air can equalize when the sewer pipes get filled and the rate of exit slows down.

You might even see the "burps" in water flow with a clear elbow.

[OldCoot]

The rush of grey water can even pull the water from the 'P' traps in the sink and lavatory and does quite often allowing the smell to permeate into the coach/trailer. I usually will go back in the trailer and run a little water in the sink & lavatory to fill the traps especially if the trailer is not going to be used for a few days.

[Herk7769]

Originally Posted by OldCoot

The rush of grey water can even pull the water from the 'P' traps in the sink and lavatory and does quite often allowing the smell to permeate into the coach/trailer. I usually will go back in the trailer and run a little water in the sink & lavatory to fill the traps especially if the trailer is not going to be used for a few days.

Excellent point. Odors in the camper can often be traced back to an empty P trap in the shower after travel. Gray water... smells.

[RudysWorld]

Odor probably caused by gray tank sucking water from P trap. I am a first time RVer and just assumed vent would keep up when dumping. After recommendations I think I will get a clear extension to place at RV. I have a clear elbow at CG sewer connection but during black tank flush there doesn't seem to be enough flow to show well. Clear extension may give a better view during flush.

Thanks to All!

[OldCoot]

I discovered it the hard way by emptying the tanks and just towing home, emptying the camper and leaving it closed up for 2 weeks. When we went in the camper to load for another trip, the odor just about knocked us back out the door. Didn't take long to figure out where it was coming from as the sink drain was right by the door. Cup of water down the drain and the smell quit coming from there. Took several days with fans blowing to get rid of the after effects of my ignorance.