# Black Tank Not Vented?



## kyoutback (Jul 12, 2004)

I know this sounds crazy but I don't see how the black tank is vented. I have had the camper for 9 years now and this is the first problem I've had that made me examine the plumbing system. The vent runs down behind the shower. I removed the access panel to see under the shower and I can see where the vent ties in there, however I don't see how the vent runs over to the black tank at all. There are no other pipes running from there towards the black tank. Is it possible that Gilligan only vented my gray tank?


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## CamperAndy (Aug 26, 2004)

Not likely, they could have vented it across in the ceiling or either under the floor. If it were not vented every time you flushed you would get a big burp back into the bathroom.


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## Oregon_Camper (Sep 13, 2004)

Get on top of your Outback, and you'll see the vent just about straight up from your toilet in the trailer. There will be a round cap on top...about 6-8" in diameter.


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## H2oSprayer (Aug 5, 2006)

If the tank was not vented, the vacuum that would be created while dumping the tank would make the tank take forever to drain (I know...say that three times fast!!). Not to mention, would probably pull the seal out of the toilet.

"Hello, this is your camper calling, please get these old Duro tires off of me before they decide to blowout on the freeway!!"


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## luverofpeanuts (Mar 9, 2010)

kyoutback said:


> I have had the camper for 9 years now and this is the first problem I've had that made me examine the plumbing system.


What is the problem? I recently replaced the black tank vent cap because I felt it was way way too restrictive due to some "smelly" experiences we've had...not often...just when really really hot out and the camper A/C is keeping the inside nice and cool.


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## kyoutback (Jul 12, 2004)

Oregon_Camper said:


> Get on top of your Outback, and you'll see the vent just about straight up from your toilet in the trailer. There will be a round cap on top...about 6-8" in diameter.


Did that! That's how I discovered it ran down behind the shower not the toilet as I expected it would.


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## kyoutback (Jul 12, 2004)

H2oSprayer said:


> If the tank was not vented, the vacuum that would be created while dumping the tank would make the tank take forever to drain (I know...say that three times fast!!). Not to mention, would probably pull the seal out of the toilet.
> 
> "Hello, this is your camper calling, please get these old Duro tires off of me before they decide to blowout on the freeway!!"


Now way am I getting rid of my tires while they still have tread and still hold air. That's just crazy talk.


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## kyoutback (Jul 12, 2004)

CamperAndy said:


> Not likely, they could have vented it across in the ceiling or either under the floor. If it were not vented every time you flushed you would get a big burp back into the bathroom.


I thought of the possibilty that they ran the vent through the roof since I checked everything down below and there are not pipes running that direction. Just seemed like a silly way to do it. I'm not opening the ceiling to find out.


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## luverofpeanuts (Mar 9, 2010)

kyoutback said:


> "Hello, this is your camper calling, please get these old Duro tires off of me before they decide to blowout on the freeway!!"


Now way am I getting rid of my tires while they still have tread and still hold air. That's just crazy talk.
[/quote]

Hmm...well, I'd keep an eye out for tread separation. I had a blowout on a tire after about 7 years, plenty of tread left, and they still held air







I inspected the other tires on the trailer and saw some serious "waves" in the tread area of the tire. I was lucky to make it home without another blow out! Luckily, there was minimal damage to the trailer.... but there as damage.


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## luverofpeanuts (Mar 9, 2010)

Is there only one round vent cap on the roof?


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## H2oSprayer (Aug 5, 2006)

luverofpeanuts said:


> "Hello, this is your camper calling, please get these old Duro tires off of me before they decide to blowout on the freeway!!"


Now way am I getting rid of my tires while they still have tread and still hold air. That's just crazy talk.
[/quote]

Hmm...well, I'd keep an eye out for tread separation. I had a blowout on a tire after about 7 years, plenty of tread left, and they still held air







I inspected the other tires on the trailer and saw some serious "waves" in the tread area of the tire. I was lucky to make it home without another blow out! Luckily, there was minimal damage to the trailer.... but there as damage.
[/quote]

Been there...done that. Ours was the last trip of the camping season a couple of years ago. I had contemplated replacing the tires before the trip, but as it was our last trip of the year, decided to hold off until spring. The decision as a bad one. The tread separated just out of Milwaukee on I94 and of course it was on the road side of the camper. Not much fun changing a flat tire with your butt hanging out in busy Friday afternoon traffic. Needless to say, we had 4 new tires for the trip home.


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## kyoutback (Jul 12, 2004)

luverofpeanuts said:


> "Hello, this is your camper calling, please get these old Duro tires off of me before they decide to blowout on the freeway!!"


Now way am I getting rid of my tires while they still have tread and still hold air. That's just crazy talk.
[/quote]

Hmm...well, I'd keep an eye out for tread separation. I had a blowout on a tire after about 7 years, plenty of tread left, and they still held air







I inspected the other tires on the trailer and saw some serious "waves" in the tread area of the tire. I was lucky to make it home without another blow out! Luckily, there was minimal damage to the trailer.... but there as damage.
[/quote]
I do keep an eye on them.


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## kyoutback (Jul 12, 2004)

luverofpeanuts said:


> Is there only one round vent cap on the roof?


Yes, only one.


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## luverofpeanuts (Mar 9, 2010)

kyoutback said:


> Is there only one round vent cap on the roof?


Yes, only one.
[/quote]

Hmm...... that is interesting.

It might be interesting to try and take a couple gallons of water and pour it down the roof vent and see what tank it goes into. I guess it wouldn't necessarily prove it's not a shared vent....but it goes into the black tank, at least you know it's vented.

Were you just curious about the venting, or were you noticing a particular problem?


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## kyoutback (Jul 12, 2004)

luverofpeanuts said:


> Is there only one round vent cap on the roof?


Yes, only one.
[/quote]

Hmm...... that is interesting.

It might be interesting to try and take a couple gallons of water and pour it down the roof vent and see what tank it goes into. I guess it wouldn't necessarily prove it's not a shared vent....but it goes into the black tank, at least you know it's vented.

/quote]

Were you just curious about the venting, or were you noticing a particular problem? 
I knew someone would eventually ask that question and I would have to fess up to my mistake. I was cleaning the tank with mr. quickie flush, filling and dumping, filling and dumping and about the third or fourth time I was filling I got distracted talking to a friend. Next think I knew I had major water running out the bottom of the camper. There was only minor water in the camper and nothing came out the vent.

After much investigating I believe the water pressure lifted the toilet from it's rubber seal and some water got in the camper. Once the initial pressure was release the rest ran out the bottom. I have since discovered small cracks in both tanks that appear to have been there for a while judging by the staining. That brings me to the only mystery left. Why didn't the water simply go up the vent? Some blockage? Non-existant vent? The world may never know.


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## CamperAndy (Aug 26, 2004)

kyoutback said:


> That brings me to the only mystery left. Why didn't the water simply go up the vent? Some blockage? Non-existant vent? The world may never know.


To rise to the roof the pressure would have had to get to about 3.6 to 4.0 psi in the tank. The seal on your toilet could not cope with that and failed before the pressure got high enough in the tank to push it up the vent. It may not sound like much pressure but it does solve the mystery.


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## H2oSprayer (Aug 5, 2006)

luverofpeanuts said:


> Is there only one round vent cap on the roof?


Yes, only one.
[/quote]

Hmm...... that is interesting.

It might be interesting to try and take a couple gallons of water and pour it down the roof vent and see what tank it goes into. I guess it wouldn't necessarily prove it's not a shared vent....but it goes into the black tank, at least you know it's vented.

Were you just curious about the venting, or were you noticing a particular problem?

[/quote]

I think it would be much easier to tell by heading to the dump station with a full black tank. When you empty the tank, does the tank gurgle as the waste is coming out? If not, it's vented. Another way to tell (albeit a much grosser way) hike up to the roof and stick your nose near the vent. You will know if it's vented or not.


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## kyoutback (Jul 12, 2004)

Both tanks are currently clean and empty. So I think I'll try the idea of pouring water down the vent and see which tank (hopefully both) receive the water.


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## Wisconsin-Knight (Mar 10, 2011)

If you have a shared vent, I think water would run up the vent and down into the grey water tank. If the junction is in the ceiling, the water pressure might have caused a leak at your toilet by the time the water reached the ceiling. At least that would explain why no water came out your vent, it went into your grey tank. Rowland


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