Anyone ever find holding tank vent pipes leaking?

[tkcas01]

First off, if you are inclined to tell me to check the autovents under the sinks, don't bother. They have all been replaced.

I've been having trouble eliminating holding tank odor from my half bath. As I said, the autovent under the vanity has been replaced multiple times. I also tried to re-seat/re-seal the toilet a couple of times to no avail.

And no, it is not the flush valve. The toilet has no problem holding water in the bowl for days on end. The only other thing I can think of is that perhaps the vent pipes going from the tanks to the roof have a broken connection somewhere.

I shot water into the roof vent down into the tank and did detect some moisture on the outside of the vent pipe going down into the holding tank. Thing is, it was not clear if it was coming out of the pipe through bad connections or a bad seal at the roof, as some of the water from the hose was spilling out of the vent.

I opened up the wall in the bath and the vent pipe is exposed from tank to roof. I plan to remove the vent cap and put a hose down the vent pipe to make sure any water coming down is INSIDE the vent pipe. That should make it clear if there is a bad pipe connection somewhere.

I should know more in a couple of days, but just wondering if anyone has ever found their vent pipes to have bad seals at the elbows and such. It's about the only thing left that could be wrong in my case.

[tkcas01]

dougrainer wrote:
Put a qt of Pine Sol in the gray tank with about 10 gallons of water and then drive the unit. See if you get the Pine sol smell. If so, you have a vent issue with the gray tank. If no Pine sol smell, flush the gray and do the same test with the black tank.

This is EXCELLENT advice. Use Pine-Sol to isolate the "offending" tank. As suggested, put some in the grey tank. Didn't even drive around but soon started smelling it.

The rig is a 1.5 bath model and the odor has been isolated around the half bath in the middle of the coach. This is right over the tanks and the vent pipe runs up through the back of the half bath.

To confirm it was not the autovents, I got down and stuck my head in all the cabinets where a sink is. No pine-sol smell. I actually smell it more just up walking around, even outside of the half bath.

SOOO, I am thinking there is a problem with the vent pipe up at the roof and odor is getting between the roof and ceiling. Will investigate further, but I think I am on the trail of it.

Thanks for the tip!

[RLS7201]

"Anyone ever find holding tank vent pipes leaking?" YES!

The black tank vent on my 95 Bounder started leaking at the connector that is screwed into the tank. The thread section cracked where it was connected to the main body of the coupling.
Had to remove the gray tank and then the black tank to remove the old threads. Very time consuming.

Richard

[alfredmay]

On some Thetford toilets there is an overflow tube that extends from near where flush water enters the top of the bowl directly to the black water tank. This is apparently intended to keep the toilet from overflowing if there is a small leak in the water valve.

The tube is curved, forming an "S" trap. If there is no water in the "S", there is a direct passage between the black water tank and the bathroom. Thus - BAD odors in your living quarters - regardless of what chemicals are in the tank.

To fill the "S" with water, simply fill the toilet to the brim. Let it stand for a couple of minutes to make sure the overflow trap is filled, and flush it down. Then, just use the toilet normally. It would probably be a good idea to repeat this a few times during the camping season, just in case the trapped water is sloshed out or evaporates.



For a diagram showing the overflow tube, see:
http://www.thetford....18/Default.aspx

[Monaco_Montclai]

only if the tank over flows --now it all happy-camping

[dougrainer]

To answer your question---NOT common to have the vent pipes leak. VERY RARE. Now, what you need to do is determine which tank is causing the odor. 99% of the time it is the GRAY tank, not the Black. Dump both tanks and fill and flush them both. Put a qt of Pine Sol in the gray tank with about 10 gallons of water and then drive the unit. See if you get the Pine sol smell. If so, you have a vent issue with the gray tank. If no Pine sol smell, flush the gray and do the same test with the black tank.
Common things that cause a tank odor
1. washer dryer prepped or w/d installed---the p trap has no water due to non use and the odor comes up there
2. Having a roof vent OPEN and the roof top tank vent, the odor is pulled in in transit thru the open vent
3. NO water in one of the sink/shower p traps(but if you use these sinks/ shower they will have water)
4. IF the 1.5 inch ABS vent pipes are not sealed in the top of the waste tanks or loose, you will get odor. The easiest test for this is to fill both tanks to where water comes up in the toilet and water flows into the shower pan. Once that water is there you check for leaks flowing off the top of the tanks.
5. LONG SHOT, but I have seen it. The wash bay, the customer keeps the dump hose and such and does not clean it out and the water bay smells horrible. THAT odor WILL migrate up into the RV as no RV has the water bay air sealed from the inside. Doug

[doxiemom11]

Our vent pipe had dropped down so that it wasn't exiting the roof. DH had to fix that. Prior to that we had odor in the MH when driving. No problem after the fix.

[bdpreece]

On my last coach the vent pipe did not exit the roof so odors would come in through the air conditioning vents. Have also heard of others where the pipe has dropped down into the tank causing this same type of problem. Only way I found mine was I removed the vent cover to replace it with a Camco Cyclone vent.