black tank smell-tried everything - Page 2

Bunkfamily · 04-07-2012, 05:47 PM

Our cardinal smelled terrible, we found out that the laundry hookup that we never used was wide open. since you never put water down it the trap was never full, we put a clamp on rubber pipe cap on it and VIOLA....odor gone

klmurphy · 04-08-2012, 08:29 AM

Thks for info regarding laundry hookup--will check that. Wonder if your smell was specific to toilet area? Would think laundry would drain in gray tanks, not black. Again, thks-worth checking everything.

Bunkfamily · 04-08-2012, 08:35 AM

Smell was hard to locate for us, one time smelled over here..then over there! Does your toilet hold water ? if it leaks by the seal then air will also come up. We try to keep a little water in the toilet to help seal the seal ,

klmurphy · 04-08-2012, 08:35 AM

OK, so if vent was installed too far into the tank, any suggestions on how a common person with limited tools can fix this? We did not have great faith in our dealer at the time and if this is labor intensive (which probably is) you can bet it was ignored and now the cost is ours. And no--we typically use the fantastic fan for forcing shower humidity out but not for encouraging toilet odors up.

klmurphy · 04-08-2012, 08:55 AM

OK-as original post msg perhaps I should have been more clear. Based on past experience, either with other RV's and/or 30+ years of household septic use, we have never had this issue. We understand not to use a fantastic fan to draw air up out of the toilet, we use the correct dissolvable toilet tissue, use the correct toilet treatment, the shower is not draining in the black tank, etc. Appreciate the tip on how to use a garden hose to check for a clogged vent pipe. If the vent pipe was installed too deep in the black tank (which seems likely at this point) does anyone know the easiest/best way to correct it? This Cardinal has metal underpinning and we understand getting to the black tank is not an easy feat. If this is something that is best handled by a RV dealer who would have the proper tools, perhaps we'll bite the bullet and pay for it...or continue as we have from day 1 and empty the tank at half full. And no, we don't continue to add water to make it at least 2/3 full before dumping--your nose & eyes wouldn't be able to stand it.

We are full-timers and make it a point to thoroughly flush our tanks every 4 weeks, if not sooner.

Bill m · 04-08-2012, 09:05 AM

If it is the vent being to low, one way to check is to measure from the top down.(with an empty tank slide a tape all the way down to tank bottom take this measure ment, then bring the tape up to hook on the vent pipe and take that measurement, lastly you need to determine how deep the actualt tank is, this may be able to be accomplished from under the unit) if the vent appears to be over 2 inches into the tank then yes it is to far in. There are three ways to change this, one drop the tank and cut the pipe (very difficult) Two undo the vent cap on the top - apply two sets of visegrips (to hold the pipe and give leverage) and lift the pipe up and cut, then reapply the vent cap and seal properly - third locate the vent interior and if accessable cut the pipe and place a lift the vent pipe and place a coupling (would prefere a nohub coupling myself) and close it up.

In any way not an easy fix but can be done. Best of luck.

LeonFournier · 04-08-2012, 09:15 AM

To check if vent length is in fact the issue, you can try the following, won't be pleasant, but will prove a problem before spending a bunch of cash on a repair that may not solve your problem.

1. Empty black water tank.
2. Turn off water feed or water pump.
3. Use a mechanics mirror with long handle and flashlight to look in the tank through the toilet opening.

If the vent pipe is actually that much longer, it should be easily spotted using mirror. If that is not the problem, then you've saved yourself money. If it is the problem then have it fixed by a qualified RV mechanic.

**Herk7769** · 04-08-2012, 09:29 AM

The "look down the toilet" method will not work in my camper. It has 2 45 degree bends in it before it drops into the black tank.

While there is a case here on the forum that the black vent had slipped into the black tank before the cement dried, IMO it would be rare indeed.

I would be concentrating my efforts on the gray tank odors. A really bad smell in the kitchen turned out to be a damp dishrag tossed into the cabinet under the sink. Forgotten about for a month between trips, it took a week of troubleshooting to find the source of that awful smell.

Fire Instructor · 04-08-2012, 10:43 AM

Another way to check, if you can't see in, is to have someone stay on the roof listening in the vent. Fill the tank, through the toilet with a garden hose. If they stop hearing incoming water before the tank fills, then the vent is too low in the tank. Once the afffluent covers the bottom of the venp pipe, the vent stops working, and the air becomes displaced out the toilet.

As it is, air dispacement when flushing is "easier" through the open toilet flap than through the vent. The flush opening is about 2-3" (I've never actually measured, just guesstamating) and the vent is only 1.5". Air will take the path of least resistance, and if the vent fan is on, the fan helps it!

**Herk7769** · 04-08-2012, 10:44 AM

Quote:

Originally Posted by Fire Instructor

Another way to check, if you can't see in, is to have someone stay on the roof listening in the vent. Fill the tank, through the toilet with a garden hose. If they stop hearing incoming water before the tank fills, then the vent is too low in the tank. Once the afffluent covers the bottom of the venp pipe, the vent stops working, and the air becomes displaced out the toilet.

As it is, air dispacement when flushing is "easier" through the open toilet flap than through the vent. The flush opening is about 2-3" (I've never actually measured, just guesstamating) and the vent is only 1.5". Air will take the path of least resistance, and if the vent fan is on, the fan helps it!

excellent idea

Fire Instructor · 04-08-2012, 10:47 AM

Another thought - If you can't figure out if it's black or gray, then bleach treat one of them, and see if you can smell it. If not, try bleaching the other. You should be able to determine which the offender is, and the bleach smell will subside with some ventlation and time.

NOTE: Bleach treat only after flushing WELL with clean water! Depending on what chemicals you use, the bleach could have an unplesant reaction....

Bill m · 04-08-2012, 10:54 AM

As far as repair the last item 4 bring it to a shop for repair:

As a plumber I have a few questions:

Is your grey tank connected to the black at all, I realize this is not common any longer but you never know.
Does your shower or lavatory sink drain into the black tank, sometimes common.
Is there a vent cross connection from your grey to black tank.
Do your sinks or shower have P traps or waterless traps, if they have waterless traps they sometimes dry out and do not close properly.
Is there water in the toilet itself and does the seal hold. (if not replace the seal on the toilet, and see if it solves the problem)
The problem with RV systems are that there are so many moving parts close to each other.
I also would check if there is a washer connection unplugged.

Fire Instructor · 04-08-2012, 11:04 AM

Sure.... I'm setting-up to tell my plumber joke, and now a REAL plumber has to jump ingto the discussion!

Well, you are better off getting advice from a pro, than from us amateurs.... So listen to Bill!!!

Bill m · 04-08-2012, 11:06 AM

we all have things to offer. RV's are a different animal, and we are all learning.

Bunkfamily · 04-08-2012, 04:15 PM

try asking over here...
Cardinal RV Club • Index page

lots of guys over there who know the layout and build of these really well. Also they have a page for dealers and you may find a recommended one near you

dezolen · 04-08-2012, 08:02 PM

I would definitely check the vents that terminate under the sinks if Cardinal still uses this cheap shortcut. Mine stink to high heaven when they don't seal. Most hardware stores sell the vent for less than 10$. Easy screw in installation.

klmurphy · 04-09-2012, 08:16 AM

Greatly appreciate everyone's responses & help. Agree, you can never learn enough. In response to Bill M "the plumber" direct questions:
1. No, our grey tanks are not connected. There is 1 grey for kitchen, 1 grey for shower/bath sink, and 1 black for toilet.
2. No, shower does not drain in black tank and there is not cross ventilation between the two/three tanks that we can tell. At least, there are separate vent caps on the roof for each, put it that way.
3. Showers & sinks have P traps.
4. Yes, there is water in the toilet after flushing and the seal does hold.

Again, thanks to all for guidance and alternate internet resources. Will double check washer connections, do the water in tank/listen topside trick and go from there. Wish it were something as simple as a moldy rag in a cabinet or not understanding what toilet paper/black tank treatment to use, but having lived in the this specific unit for almost 2 years, can tell you it is definitely a plumbing issue somewhere. And ONLY when the black tank gets 1/2 full. Not when one or both grey tanks are empty, half, or full or anywhere in between. Not when black tank is 1/3 full--only around the 20-21 gallon range. Doesn't matter if it is 30 degrees outside or 90 degrees. Agree with most that a bad smell is sometimes hard to distinguish between black/grey tanks but when it is really really bad, most folks can tell the difference. Again, some great suggestions and appreciate everyone's input.

Bill m · 04-09-2012, 07:33 PM

This being the case it sure sounds like the vent. Try calling FR or your service facility and ask how the vent is attached, I have heard of them sliding down and in to the tank, If this is the case grabbing it from the top you may be able to pull it back up and then cut to the required length. Be careful not to take it out of the tank itself. Good luck we are all rooting for success.

BCrawford · 09-01-2012, 06:49 PM

This thread has been very helpful for me. I have a similar problem to the original posrter in that after 2-3 days of use the smell from the black water tank when flushing would drive you out of the trailer. I have tried a number of deodorizers etc and complained to dealer several times that the tank cant be vented. They check the vent and said everything was fine. After about a year of grumbling I started digging deeper and I found something very interesting. I pulled the cap of the black water vent and after flushing the tanl measured from the vent top to the bottom of the tank. 114 inches. I then fished until I hooked the tape measure on the bottom og the vent stack 112.5 inches. Thats right 1.5 inch from the bottom of the tank to the bottom of the vent. It is about 5.5 inches to the bottom of the toilet from the botton of the tasnk. Once 1.5 inch of fluid in the tank, bingo - no more venting. Dealer is coming to site to drop the BW tank on Tuesday. I would be interested if original poster resolved their problem or not.

BCrawford · 09-04-2012, 06:11 PM

Dealer service personnel were on site today and after preparing to drop the BW tank, one of them suggested trying to pull the vent stack upward from the roof. Apparently the vent was not glued into the top of the tank so they were able to slide the vent up. The is now 5" between the bottom of tank and bottom of the vent. This should fix that awful smell we were getting when the tank showed was more than 1/3 full.

We will know for sure next weekend.

You may also like: